Three-phase reaction system for hydrogenation reaction of organics

Abstract

Systems and methods for hydrogenation of unsaturated compounds are described herein. In some embodiments, the disclosed systems and methods enable hydrogenation of unsaturated compounds within a triphasic reaction environment. In some cases, contacting an aqueous phase including a reduced mediator, a nonaqueous phase including an unsaturated compound, and a catalyst results in formation of a hydrogenated product and a corresponding oxidized mediator. In some embodiments, the system includes an electrochemical cell and a reactor. In some embodiments, the reduction of the mediator and the hydrogenation of the unsaturated compound are spatially decoupled, allowing the mediator to be regenerated electrochemically in one location and utilized for hydrogenation in another.

Description

[0001] PATENT

[0002] Attorney Docket No. 51198-070W02

[0003] THREE-PHASE REACTION SYSTEM FOR HYDROGENATION REACTION OF ORGANICS Cross-Reference to Related Applications

[0004] This application claims priority to and the benefit of U.S. Provisional Patent Application No.

[0005] 63 / 776,550, filed March 24, 2025, the disclosure of which is hereby incorporated by reference herein in its entirety.

[0006] Technical Field

[0007] Embodiments described herein relate to systems, components, and methods for hydrogenation of unsaturated compounds.

[0008] Background of the Invention

[0009] Hydrogenation reactions are widely used in chemical synthesis, energy conversion, and materials processing to reduce unsaturated compounds, including alkenes, alkynes, carbonyl compounds, nitro compounds, and other reducible functional groups. Conventional hydrogenation methods employ hydrogen gas in presence of a catalyst. Catalytic hydrogenation desires metal activation, high partial pressure of hydrogen gas, and / or elevated temperature. In addition, catalytic hydrogenation generates substantial amount of waste, raising environmental and safety concerns. Electrochemical reduction methods have recently emerged as a promising alternative which enables organic reactions under ambient conditions. However, most organic compounds, particularly hydrocarbons, exhibit extremely low solubility in water. In addition, the conventional electrochemical reaction methods suffer from low conductivity, low selectivity, poor stability of the components, limited efficiency of reaction, and / or high purification costs. Accordingly, improved hydrogenations method and systems are desired.

[0010] Summary of the Invention

[0011] Embodiments described herein relate to systems, methods, devices, and compounds for hydrogenation of an unsaturated compound. In some aspects, a method includes contacting an aqueous phase including a mediator in a reduced state, a nonaqueous phase including an unsaturated compound, and a solid phase including a catalyst, to afford a hydrogenated product and the mediator in an oxidized state.

[0012] In some embodiments, a method includes contacting a solid phase including a catalyst with a nonaqueous phase including a reactant, the reactant having an unsaturated compound, and an aqueous phase including an organic mediator in a reduced state. In some embodiments, the method further includes allowing a hydrogen species to transfer from the aqueous phase to the reactant via the catalyst forming a hydrogenated product.

[0013] In some embodiments, a system includes an electrochemical cell including a mediator in an aqueous phase, a reactor including a nonaqueous phase including an unsaturated compound, and a solidPATENT

[0014] Attorney Docket No. 51198-070W02

[0015] phase including a catalyst and being fluidically couplable with the electrochemical cell. In some embodiments, the reactor is configured to receive at least a portion of the aqueous phase including the mediator in the reduced state and contact the mediator in the reduced state with the catalyst to form a hydrogenated product in the nonaqueous phase.

[0016] In one aspect, the invention provides a method of forming a hydrogenated product including contacting an aqueous phase including a mediator in a reduced state, a nonaqueous phase including an unsaturated compound, and a solid phase including a catalyst, to afford the hydrogenated product and the mediator in an oxidized state.

[0017] In some embodiments, the method of affording the hydrogenated product and the oxidized mediator is via hydrogenation of the unsaturated compound and oxidation of the mediator in the reduced state, the hydrogenation and oxidation facilitated by the catalyst. In some embodiments, a hydrogen species is transferred from the mediator in the reduced state to the unsaturated compound.

[0018] In some embodiments, the catalyst is a metal, a metal oxide, or a metal sulfide catalyst includes at least one of palladium (Pd), platinum (Pt), nickel (Ni), cobalt (Co), iron (Fe), rhenium (Re), rhodium (Rh), ruthenium (Ru), iridium (Ir), manganese (Mn), molybdenum (Mo), and copper (Cu). In some embodiments, the catalyst includes a support coupled to at least one of the metal, the metal oxide, or the metal sulfide. In some embodiments, the support includes carbon. In some embodiments, the catalyst includes nickel or copper and has a porous structure, the porous structure formed by leaching aluminum from a nickel-aluminum alloy or a copper-aluminum alloy. In some embodiments, the catalyst includes Pd / C.

[0019] In some embodiments, the solid phase is amphipathic. In some embodiments, the solid phase at least partially localizes at an interface between the aqueous phase and the nonaqueous phase. In some embodiments, the solid phase includes polytetrafluoroethylene (PTFE).

[0020] In some embodiments, the mediator includes at least one of a phenazine, quinoxaline, anthraquinone, naphthoquinone, benzoquinone, fluorenone, azo-compound, phenoxazine, phenothiazine, alloxazine, isoalloxazine, and / or bipyridinium. In some embodiments, the mediator includes at least one of vanadium or chromium.

[0021] In some embodiments, the mediator includes a compound of formula (I):

[0022] H

[0023]

[0024] OOC

[0025] (I), or a salt thereof.

[0026] In some embodiments, the mediator includes a compound of formula (II):PATENT

[0027] Attorney Docket No. 51198-070W02

[0028]

[0029] or a salt thereof.

[0030] In some embodiments, the mediator includes a compound of formula (III):

[0031] O

[0032]

[0033] O (III), or a salt thereof.

[0034] In some embodiments, the unsaturated compound includes at least one group selected from an alkene (e.g., C=C), an alkyne (e.g., C=C), a carbonyl (e.g., C=O), or a reducible nitrogen (e.g., azo, hydroxamic acid, hydroxyl amine, N-oxide, nitrite (e.g., RONO), nitro (e.g., R-NO2), nitroso (e.g., R-NO), nitrene precursor (e.g., R-N:), and a nitrile (e.g., R-C=N)).

[0035] In some embodiments, the method of contacting the aqueous phase, the nonaqueous phase, and the solid phase occurs in a reactor.

[0036] In some embodiments, the method further includes reducing a mediator to form the mediator in the reduced state in an electrochemical cell. In some embodiments, the method further includes separating the solid phase from the aqueous phase and the nonaqueous phase. In some embodiments, the method further includes transferring the aqueous phase to the electrochemical cell. In some embodiments, the hydrogenated product is a fully hydrogenated product or a partially hydrogenated product.

[0037] In another aspect, the invention provides a method including, contacting a solid phase including catalyst with a nonaqueous phase including a reactant, including an unsaturated compound, and an aqueous phase including a mediator in a reduced state, and allowing a hydrogen species to transfer from the aqueous phase to the reactant via the catalyst to form a hydrogenated product.

[0038] In some embodiments, the unsaturated compound includes at least one group selected from an alkene (e.g., C=C), an alkyne (e.g., C=C), a carbonyl (e.g., C=O), or a reducible nitrogen (e.g., azo, hydroxamic acid, hydroxyl amine, N-oxide, nitrite (e.g., RONO), nitro (e.g., R-NO2), nitroso (e.g., R-NO), nitrene precursor (e.g., R-N:), and a nitrile (e.g., R-C=N)).

[0039] In some embodiments, the method further includes, prior to the contacting, reducing a mediator to form the mediator in the reduced state in an electrochemical cell. In some embodiments, the electrochemical cell includes a cathode and a cathode region configured to receive an alkaline aqueous solution including the mediator.

[0040] In some embodiments, the electrochemical cell includes a membrane configured to separate an anode from the cathode, wherein the membrane is configured to prevent oxidation of the mediator in the reduced state. In some embodiments, the membrane is a size-exclusion membrane or a protonexchange membrane.PATENT

[0041] Attorney Docket No. 51198-070W02

[0042] In some embodiments, the method further includes transporting the aqueous phase including the mediator in the reduced state to a reactor fluidically coupled to the electrochemical cell, wherein the contacting occurs in the reactor. In some embodiments, the contacting includes agitating the aqueous phase, the nonaqueous phase, and the solid phase such that at least a portion of the solid phase is at an interface between the aqueous phase and the nonaqueous phase.

[0043] In some embodiments, the mediator includes a phenazine, quinoxaline, anthraquinone, naphthoquinone, benzoquinone, fluorenone, azo-compound, phenoxazine, phenothiazine, alloxazine, isoalloxazine, bipyridinium, vanadium, and / or chromium. In some embodiments, the mediator has a potential, under reaction conditions, that is more negative than an underpotential deposition threshold (Vupd) for deposition of the hydrogen species on the catalyst.

[0044] In some embodiments, at least a portion of the solid phase localizes at an interface between the aqueous phase and the nonaqueous phase.

[0045] In some embodiments, the hydrogenated product is a fully hydrogenated product or a partially hydrogenated product.

[0046] In another aspect, the invention provides a system including, an electrochemical cell including a mediator in an aqueous phase and a reactor including a nonaqueous phase including an unsaturated compound and a solid phase including a catalyst and being fluidically couplable to the electrochemical cell, wherein the reactor is configured to receive at least a portion of the aqueous phase to contact the mediator in the reduced state with the catalyst to form a hydrogenated product in the nonaqueous phase.

[0047] In some embodiments, the unsaturated compound includes at least one group selected from alkene (e.g., C=C), an alkyne (e.g., C=C), a carbonyl (e.g., C=O), or a reducible nitrogen (e.g., azo, hydroxamic acid, hydroxyl amine, N-oxide, nitrite (e.g., RONO), nitro (e.g., R-NO2), nitroso (e.g., R-NO), nitrene precursor (e.g., R-N:), and a nitrile (e.g., R-C=N)).

[0048] In some embodiments, the system further includes an agitator configured to agitate the aqueous phase, the nonaqueous phase, and the solid phase. In some embodiments, the system further includes a first separator fluidically couplable to the reactor, the first separator configured to separate the solid phase from the aqueous and nonaqueous phases to form a second mixture including the aqueous phase and the nonaqueous phase. In some embodiments, the system further includes a second separator fluidically couplable to the first separator, the second separator configured to receive the second mixture and separate the aqueous phase from the nonaqueous phase.

[0049] In some embodiments, the system further includes a recirculation assembly fluidically coupled to at least one of the electrochemical cell, the reactor, the first separator, or the second separator, the recirculation assembly configured to transfer at least a portion of the separated solid phase from the first separator to the reactor or transfer at least a portion of the separated aqueous phase to the electrochemical cell.PATENT

[0050] Attorney Docket No. 51198-070W02

[0051] Brief Description of the Drawings

[0052] FIG. 1 is a block diagram of a system for production of hydrogenated products from unsaturated compounds, according to an embodiment.

[0053] FIG. 2 is a diagram of a system for continuous production of a hydrogenated product, according to an embodiment.

[0054] FIG. 3 illustrates a hydrogenation reaction in a three phasic system, according to an embodiment. FIG. 4 is a diagram of a continuous method for production of a hydrogenated product, according to an embodiment.

[0055] FIGS. 5A-5B illustrate a two-step hydrogenation mechanism, according to an embodiment.

[0056] FIG. 6 illustrates a solid phase, including a catalyst, according to an embodiment.

[0057] FIG. 7 illustrates schematic representation of localization of a solid phase including a catalyst, according to an embodiment.

[0058] FIG. 8 illustrates the effect of inclusion of a catalyst in an amphipathic solid phase on localization of the catalyst.

[0059] FIG. 9 illustrates electrochemical potential diagram of mediators, unsaturated compounds, and hydrogenated products, according to an embodiment.

[0060] FIG. 10 illustrates cyclic voltammograms of selected mediators and a catalyst.

[0061] FIG. 11 illustrates hydrogenation rate for a molecule-driven condition and a potential-driven condition. FIG. 12A shows the effect of catalyst mass on hydrogenation rate over time. FIG. 12B shows the effect of stirring rate on hydrogenation rate over time. FIG. 12C shows the effect of mediator on hydrogenation rate of styrene over time.

[0062] FIGS. 13A-13C illustrate the effect of the mediator concentration (FIG. 13A), the reactant concentration (FIG. 13B), and state of charge (SOC, FIG. 13C) on hydrogenation of the reactant, styrene.

[0063] FIGS. 14A-14C illustrate the effect of different mediators on hydrogenation of different unsaturated compounds.

[0064] FIG. 15 shows the in situ X-ray diffraction (XRD) cell setup for monitoring the hydrogenation process. FIG. 16 shows the XRD results for a catalyst sample exposed to different mediators and an unsaturated compound.

[0065] FIG. 17 shows a flow diagram of a method for hydrogenation of an unsaturated compound.

[0066] Detailed Description

[0067] Hydrogenation reactions are generally used for the conversion of unsaturated compound into more saturated products (e.g., partially or fully saturated products) across chemical, pharmaceutical, andPATENT

[0068] Attorney Docket No. 51198-070W02

[0069] materials processing industries. Such reactions are commonly used to modify molecular structure, adjust physical properties, improve chemical stability, and / or generate intermediates and finished products.

[0070] In conventional hydrogenation processes, unsaturated compounds can be reduced with molecular hydrogen in the presence of a catalyst, typically a transition metal catalyst. The hydrogenation reaction proceeds via adsorption of molecular hydrogen and the unsaturated compound onto the catalyst surface, followed by hydrogen addition across one or more unsaturated bonds. Catalytic hydrogenation often relies on activation of a metal catalyst, the use of elevated hydrogen partial pressures and / or increased reaction temperatures to achieve acceptable reaction rates and conversion efficiencies. These operating conditions can increase energy consumption and impose additional equipment, including high-pressure reactors, hydrogen storage systems, and safety controls to mitigate risks associated with hydrogen handling.

[0071] Moreover, conventional catalytic hydrogenation processes can exhibit limited selectivity, particularly when reactants contain multiple reducible functional groups, which may result in over hydrogenation or formation of undesired byproducts. Catalyst deactivation due to poisoning, sintering, or fouling can further reduce process efficiency and necessitate frequent catalyst replacement. Moreover, conventional catalytic hydrogenation processes can generate substantial quantities of chemical waste, including spent catalysts, solvents, and byproducts, which can raise environmental, handling, and disposal concerns.

[0072] Electrocatalytic hydrogenation is another method for hydrogenation which uses electrons and water as reductants to convert unsaturated compounds into hydrogenated products, potentially providing control over reaction selectivity and reaction rate. Such methods as a potential alternative to traditional catalytic hydrogenation can enable hydrogenation under relatively mild or ambient conditions without the direct use of molecular hydrogen. In addition, these methods can facilitate decarbonized chemical production. Electrocatalytic hydrogenation processes, while offering potential advantages over conventional methods, can suffer from several technical and practical limitations. Many organic reactants exhibit limited solubility in aqueous media, which constrains aqueous electroreduction approaches, while nonaqueous electroreduction systems can suffer from low ionic conductivity, complex cell architectures, and / or increased downstream separation processes.

[0073] In addition, mass transport is another limitation of electrocatalytic hydrogenation, particularly for water insoluble or poorly soluble organic substrates resulting in low effective reaction rate and inefficient utilization of electrode surface area. In addition, electrocatalytic hydrogenation cells often include specialized materials, such as corrosion resistant electrodes which can increase system cost and complexity. Moreover, separation and purification of products from electrolytes, solvents, or supporting solvents can be energy-intensive and offset the environmental benefits associated with electrochemical hydrogenation.

[0074] The present invention provides a scalable three phasic electrochemical hydrogenation, e.g., to address the limitations in existing methods of hydrogenation. Systems, methods, and components for hydrogenation of unsaturated compounds are described herein. In particular, the systems, methods,PATENT

[0075] Attorney Docket No. 51198-070W02

[0076] and components described herein can offer a hydrogen gas-free method for scalable and selective hydrogenation with improved efficiency for unsaturated compounds. This process can be carried out in batch mode or via continuous flow in a multiphasic system.

[0077] In some embodiments, an aqueous phase including a mediator (also referred to as redox active molecule) can flow through a first module and form a reduced mediator via electrochemical reduction. The reduced mediator can serve as a reversible hydrogen species carrier, undergoing electroreduction to store one or more hydrogen species or hydrogen equivalents, which are subsequently delivered to a reactant, e.g., via a catalyst. In some embodiment, the reduced mediator can shuttle reducing equivalents (e.g., two electrons and two protons) from a first phase including the reduced mediator to a solid phase including a catalyst, which interacts with a second phase, for example, a nonaqueous phase including the reactant, which can result in hydrogenation reaction of the reactant. In some embodiments, hydrogenation reaction can occur using electrons and water which are green reductants. Therefore, hydrogenation can occur without the gaseous molecular hydrogen. In some embodiments, the aqueous phase including the reduced mediator can be transferred to a separate chamber, where it contacts a nonaqueous phase including the reactant and a solid phase including a catalyst.

[0078] In some embodiments, the system can include an aqueous phase and a nonaqueous phase that are immiscible under the operating conditions. The immiscibility of the two phases can promote the formation of a distinct liquid-liquid interface, which may facilitate interfacial mass transfer, catalyst localization, or phase-selective reaction pathways. In certain embodiments, the mutual solubility of the aqueous phase in the nonaqueous phase, and the nonaqueous phase in the aqueous phase, can each be less than about 10 g per 100 g (e.g., less than about 10 g per 100 g, about 9 g per 100g, about 8 g per 100 g, about 7 g per 100 g, about 6 g per 100 g, about 5 g per 100 g, about 4 g per 100 g, about 3 g per 100 g, about 2 g per 100 g, or about 1 g per 100 g) of the corresponding phase. In some embodiments, the low mutual solubility can inhibit undesired phase mixing, preserve the chemical stability of phase-specific components (e.g., mediators, catalysts, reactants), and maintain well-defined reaction zones. In further embodiments, the degree of immiscibility or solubility between the phases can depend on temperature, ionic strength, solvent composition, and the presence of surface modifiers or surfactants, and can be adjusted to optimize reaction efficiency, selectivity, or mass transport. In some embodiments, the low miscibility of aqueous phase and the nonaqueous phase can improve the efficiency of the hydrogenation reaction and the separation process.

[0079] In some embodiments, reversible and stable proton-coupled redox active molecules (RAOMs) can be used. In some embodiments, the RAOM can be referred to as the mediator. In some embodiments, the RAOMs can include at least one of vanadium complexes, chromium complexes, phenazines, quinoxalines, anthraquinones, naphthoquinone, benzoquinones, fluorenones, azo compounds, a phenoxazine, a phenothiazine, an alloxazine, an isoalloxazine, and / or bipyridiniums (viologens). In some embodiments, the chemical structure of RAOMs (referred to herein as mediator) can be engineered to be soluble in the aqueous phase. In some embodiments, the mediators described herein can offer robust aqueous mediators derived from phenazine which can support continuousPATENT

[0080] Attorney Docket No. 51198-070W02

[0081] operation in a system including the electrochemical flow cell and the reactor / separator. In some embodiments, the system can be referred to as flow triphasic reduction.

[0082] Suitable mediators include an anthraquinone or a redox state thereof (e.g., a single or two electron reduced state). In some embodiments, the redox state of the anthraquinone is of formula (la).

[0083] R8

[0084] R^ R7

[0085] R3R6

[0086]

[0087] R R5(la), or a salt or tautomer thereof.

[0088] In some embodiments, the redox state of the anthraquinone is an anthrahydroquinone, e.g., an anthrahydroquinone of formula (lb)

[0089]

[0090] both Xs are H. In some embodiments, both X are absent (i.e., both O are negatively charged). In some embodiments, one X is H, and one X is absent.

[0091] In some embodiments, the redox state of the anthraquinone is an anthrahydroquinone, e.g., an anthrahydroquinone of formula (Ic)

[0092]

[0093] wherein X is H or absent, or a salt or tautomer thereof.

[0094] In some embodiments, a suitable redox active species is the reduced form of an anthraquinone, a hydroquinone, e.g., a hydroquinone of formula (Id)PATENT

[0095] Attorney Docket No. 51198-070W02

[0096]

[0097] (Id), or a salt, deprotonated form, or tautomer thereof. In any of formulas (la), (lb), (Io), or (Id) each of R1, R2, R3, R4, R5, R6, R7and R8is, independently, selected from H; halo; optionally substituted C1-6 alkyl; oxo; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; -ON; -NO2; -ORa (e.g., hydroxyl or C1-6 alkoxy); -SRa (e.g., thiol or C1-6 alkyl thio); -N(Ra)2-3 (e.g., amino); -C(=O)Ra; -C(=O)ORa (e.g., carboxyl); -S(=O)2Ra; -S(=O)2ORa (e.g., SO3H); -P(=O)Ra2; and -P(=O)(ORa)2 (e.g., phosphonyl or phosphoryl); or any two adjacent groups selected from R1, R2, R3, and R4are joined to form an optionally substituted 3-6 membered ring, or an ion thereof, where each Rais, independently, H; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S.

[0098] In certain embodiments, each of R1, R2, R3, R4, R5, R6, R7and R8is, independently, selected from halo, hydroxyl, carboxyl, sulfonate / sulfonic acid, alkylsulfonate / alkylsulfonic acid, phosphonyl, phosphoryl, alkylphosphonate / alkylphosphonic acid, amino, quaternary ammonium (e.g., trialkyl ammonium), alkyl, heteroalkyl, alkoxy, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, nitro, nitrile, thiol, and / or carbonyl groups, any of which is optionally substituted, or, any two adjacent groups of R1-R8can be joined together to form an optionally-substituted ring.

[0099] In certain embodiments, each of R1, R2, R3, R4, R5, R6, R7and R8is, independently, selected from H, optionally substituted C1-6 alkyl, halo, hydroxyl, optionally substituted C1-6 alkoxy, SO3H, amino, nitro, carboxyl, phosphoryl, phosphonyl, and oxo, or an ion thereof. In particular embodiments, each of R1, R2, R3, R4, R5, R6, R7, and R8is, independently, selected from H, hydroxyl, optionally substituted C1-4 alkyl, carboxyl, and SO3H, such as each of R1, R2, R3, R4, R5, R6, R7and R8being independently selected from H, hydroxyl, optionally substituted C1-4 alkyl (e.g., methyl), and oxo. In embodiments, at least one (e.g., at least one, two, three, four, five, or six) of R1, R2, R3, R4, R5, R6, R7, and R8is not H. In other embodiments, the anthraquinone, such as a 9,10-anthraquinone, is substituted with at least one hydroxyl group and optionally further substituted with a C1-4 alkyl, such as methyl. Exemplary anthraquinones include is 2,6-bis(3-phosphonopropyl-1 -oxy)anthraquinone (DPPEAQ),

[0100] 2,6-dihydroxy-9,10-anthraquinone (2,6-DHAQ), 1 ,5-dimethyl-2,6-dihydroxy-9,10-anthraquinone, 2,3,6,7-tetrahydroxy-9,10-anthraquinone, 1 ,3,5,7-tetrahydroxy-2,4,6,8-tetramethyl-9,10-PATENT

[0101] Attorney Docket No. 51198-070W02

[0102] anthraquinone, and 2,7-dihydroxy-1 ,8-dimethyl-9,10-anthraquinone. Ions and reduced species thereof are also contemplated.

[0103] Exemplary phenazines, N,N'-disubstituted phenazines, monoquaternized phenazines, or N,N'- diquaternized phenazines are of formula (le):

[0104]

[0105] NRX and Y is NRY; where RX and RY are independently selected from H; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; where each of R1, R2, R3, R4, R5, R6, R7and R8is, independently, selected from H; halo; optionally substituted C1-6 alkyl; oxo; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; -ON; -NO2; -ORa (e.g., hydroxyl or C1-6 alkoxy); -SRa (e.g., thiol or C1-6 alkyl thio); -N(Ra)2-3 (e.g., amino); -C(=O)Ra; -C(=O)ORa (e.g., carboxyl); -S(=O)2Ra; - S(=O)2ORa (e.g., SO3H); -P(=O)Ra2; and -P(=O)(ORa)2 (e.g., phosphonyl or phosphoryl); or any two adjacent groups selected from R1, R2, R3, and R4are joined to form an optionally substituted 3-6 membered ring, or an ion thereof, where each Rais, independently, H; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S. In certain embodiments, each of R1, R2, R3, R4, R5, R6, R7and R8is, independently, selected from H, optionally substituted C1-6 alkyl, halo, hydroxyl, optionally substituted C1-6 alkoxy, SO3H, amino, nitro, carboxyl, phosphoryl, phosphonyl, and oxo, or an ion thereof. In particular embodiments, each of R1, R2, R3, R4, R5, R6, R7and R8is, independently, selected from H, hydroxyl, optionally substituted C1-4 alkyl, carboxyl, and SO3H, such as each of R1, R2, R3, R4, R5, R6, R7and R8being independently selected from H, hydroxyl, optionally substituted C1-4 alkyl (e.g., methyl), and oxo. In embodiments, at least one (e.g., at least one, two, three, four, five, or six) of R1, R2, R3, R4, R5, R6, R7and R8is not H. In some embodiments, at least one of R1-R8is a substituted alky or substituted alkoxy.

[0106] In certain embodiments, each of R1, R2, R3, R4, R5, R6, R7and R8is, independently, selected from halo, hydroxyl, carboxyl, sulfonate / sulfonic acid, alkylsulfonate / alkylsulfonic acid, phosphonyl,PATENT

[0107] Attorney Docket No. 51198-070W02

[0108] phosphoryl, alkylphosphonate / alkylphosphonic acid, amino, quaternary ammonium (e.g., trialkylammonium), alkyl, heteroalkyl, alkoxy, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, nitro, nitrile, thiol, and / or carbonyl groups, any of which is optionally substituted, or, any two adjacent groups of R1-R8can be joined together to form an optionally-substituted ring.

[0109] In certain embodiments, the phenazine is of the formula (If):

[0110]

[0111] R5R4 (if),

[0112] or a salt or reduced form thereof, wherein each of R1, R2, R3, R4, Rs, Re, R7 and Rs is, independently, selected from H; halo; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; -ON; -NO2; -ORa; -SRa; -N(Ra)2-s; -C(=O)Ra; -C(=O)ORa; -S(=O)2Ra; -S(=O)2ORa; -P(=O)Ra2; and -P(=O)(ORa)2, wherein each Rais, independently H; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S, wherein at least one (e.g., at least one, two, three, four, five, or six) of R1, R2, R3, R4, Rs, Re, R7 and Rs is -O-(CH2)nSO3H, wherein n is 1 to 6, or wherein at least one (e.g., at least one, two, three, four, or five) of R1, R2, R3, R4, Rs, Re, R7 and Rs is -ON and at least one (e.g., at least one, two, three, four, or five) of R1, R2, R3, R4, Rs, Re, R7 and Rs is hydroxy. Exemplary phenoxazines and phenothiazines are of formula (Ig):

[0113]

[0114] or a reduced form thereof, or a salt thereof, wherein dashed bonds are single or double bonds; wherein X is N or NRX, Y is O or S, and Z is CR6, C=O, C=S, C=NRZ, or C=NH+RZ; wherein RX is selected from H; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S, wherein RZ is selected from H; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to fourPATENT

[0115] Attorney Docket No. 51198-070W02

[0116] heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; wherein each R1, R2, R3, R4, Rs, Re, R7 and Rs is, independently, selected from H; halo; optionally substituted C1-6 alkyl; oxo; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; -ON; -NO2; -ORa (e.g., hydroxyl or C1-6 alkoxy); -SRa (e.g., thiol or C1-6 alkyl thio); -N(Ra)2-3 (e.g., amino); -C(=O)Ra; -C(=O)ORa (e.g., carboxyl); -S(=O)2Ra; -S(=O)2ORa (e.g., SO3H); -P(=O)Ra2; and -P(=O)(ORa)2 (e.g., phosphonyl or phosphoryl); or any two adjacent groups selected from R1, R2, R3, and R4are joined to form an optionally substituted 3-6 membered ring, or an ion thereof, where each Rais, independently, H; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S. In certain embodiments, each of R1, R2, R3, R4, Rs, Re, R7 and Rs is, independently, selected from H, optionally substituted C1-6 alkyl, halo, hydroxyl, optionally substituted C1-6 alkoxy, SO3H, amino, nitro, carboxyl, phosphoryl, phosphonyl, and oxo, or an ion thereof. In particular embodiments, each of R1, R2, R3, R4, R5, R6, R7and R8is, independently, selected from H, hydroxyl, optionally substituted C1-4 alkyl, carboxyl, and SO3H, such as each of R1, R2, R3, R4, Rs, Re, R7 and Rs being independently selected from H, hydroxyl, optionally substituted C1-4 alkyl (e.g., methyl), and oxo. In embodiments, at least one (e.g., at least one, two, three, four, five, or six) of R1, R2, R3, R4, Rs, Re, R7 and Rs is not H. In some embodiments, at least one of R1-R8is a substituted alky or substituted alkoxy.

[0117] Exemplary reduced diquaternized bipyridines are of formula (Ih):

[0118] Y

[0119]

[0120] l’Xl~N^ - C "N+~X2

[0121] ' - ' ' - '- Y2

[0122] (Ih), a reduced form thereof (e.g., singly reduced radical monocations or doubly reduced 4,4'-bipyridi nylidenes) , or a salt thereof, where X1 and X2 are independently optionally substituted C1-20 hydrocarbyl (e.g., C1-10 alkylene) or heteroalkylene, and Y1 and Y2 are independently an optionally substituted water solubilizing group, e.g., a quaternary ammonium (e.g., trimethyl ammonium), ammonium, nitrogen containing heterocyclyl, sulfonate, or sulfate. In certain embodiments, Xi and X2 are independently C1-10 alkylene, e.g., C3-6 alkylene.

[0123] Exemplary groups for Y1 and Y2 are quaternary ammonium independently substituted with three C1-6 hydrocarbyl groups, e.g., trimethyl ammonium. An exemplary diquaternized bipyridine is of formula (II)

[0124]

[0125] In some embodiments, the mediator is a naphthoquinone. Exemplary naphthoquinones are of formula (Ij):PATENT

[0126] Attorney Docket No. 51198-070W02

[0127]

[0128] a reduced form thereof (e.g., a naphthohydroquinone), or a salt thereof, wherein the dashed bonds are single or double bonds; wherein either W and X, W and Z, or Z and Y are C=O, and wherein two of W, X, Y, or Z that is not C=O are, independently, selected from C-R, wherein R is H; halo; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; -ON; -NO2; -ORa (e.g., hydroxyl or C1-6 alkoxy); -SRa (e.g., thiol or C1-6 alkyl thio); -N(Ra)2-3 (e.g., amino); -C(=O)Ra; -C(=O)ORa (e.g., carboxyl); -S(=O)2Ra; -S(=O)2ORa (e.g., SO3H); -P(=O)Ra2; and -P(=O)(ORa)2 (e.g., phosphonyl or phosphoryl); or any two adjacent R groups are joined to form an optionally substituted non-aromatic 3-6 membered ring, or an ion thereof, wherein each Rais, independently, H; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; wherein each of R1, R2, R3, and R4 is, independently, selected from H; halo; optionally substituted C1-6 alkyl; oxo; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; -ON; -NO2; -ORa (e.g., hydroxyl or C1-6 alkoxy); -SRa (e.g., thiol or C1-6 alkyl thio); -N(Ra)2-3 (e.g., amino); -C(=O)Ra; -C(=O)ORa (e.g., carboxyl); -S(=O)2Ra; -S(=O)2ORa (e.g., SO3H); -P(=O)Ra2; and -P(=O)(ORa)2 (e.g., phosphonyl or phosphoryl); or any two adjacent groups selected from R1, R2, R3, and R4are joined to form an optionally substituted 3-6 membered ring, where each Rais, independently, H; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S. In certain embodiments, W and Z are C=O. In certain embodiments, each of R1, R2, R3, and R4 is, independently, selected from H, optionally substituted C1-6 alkyl, halo, hydroxyl, optionally substituted C1-6 alkoxy, SO3H, amino, nitro, carboxyl, phosphoryl, phosphonyl, and oxo, or an ion thereof.

[0129] In particular embodiments, each of R1, R2, R3, and R4 is, independently, selected from H, hydroxyl, optionally substituted C1-4 alkyl, carboxyl, and SO3H, such as each of R1, R2, R3, and R4beingPATENT

[0130] Attorney Docket No. 51198-070W02

[0131] independently selected from H, hydroxyl, optionally substituted C1-4 alkyl (e.g., methyl), and oxo. In embodiments, at least one, e.g., at least two, of R1, R2, R3, and R4 is not H. In some embodiments, at least one of R1-R4 is a substituted alky or substituted alkoxy. Ions and reduced species thereof are also contemplated.

[0132] Exemplary fluorenones are of formula (Ik):

[0133]

[0134] reduced forms thereof (e.g., single or two electron reduced form), and salts thereof, wherein each of Ri, R2, RS, R4, RS, Re, R? and Rs is, independently, selected from H; halo; optionally substituted C1-6 alkyl; oxo; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; -ON; -NO2; -ORa (e.g., hydroxyl or C1-6 alkoxy); -SRa (e.g., thiol or C1-6 alkyl thio); -N(Ra)2-3 (e.g., amino); -C(=O)Ra; -C(=O)ORa (e.g., carboxyl); -S(=O)2Ra; -S(=O)2ORa (e.g., SO3H); -P(=O)Ra2; and -P(=O)(ORa)2 (e.g., phosphonyl or phosphoryl); or any two adjacent groups selected from R1, R2, R3, and R4are joined to form an optionally substituted 3-6 membered ring, or an ion thereof, where each Ra is, independently, H; optionally substituted C1-6 alkyl; optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S.

[0135] In certain embodiments, each of R1, R2, R3, R4, R5, R6, R7and R8is, independently, selected from H, optionally substituted C1-6 alkyl, halo, hydroxyl, optionally substituted C1-6 alkoxy, SO3H, amino, nitro, carboxyl, phosphoryl, phosphonyl, and oxo, or an ion thereof. In particular embodiments, each of R1, R2, R3, R4, R5, R6, R7and R8is, independently, selected from H, hydroxyl, optionally substituted C1-4 alkyl, carboxyl, and SO3H, such as each of R1, R2, R3, R4, R5, R6, R7and R8being independently selected from H, hydroxyl, optionally substituted C1-4 alkyl (e.g., methyl), and oxo. In embodiments, at least one (e.g., at least one, two, three, four, five, or six) of R1, R2, R3, R4, R5, R6, R7and R8is not H. In some embodiments, the compound is an alloxazine of formula (Im):PATENT

[0136] Attorney Docket No. 51198-070W02

[0137]

[0138] or isoalloxane of formula (In)

[0139]

[0140] wherein each of R9and R10is, independently, H; optionally substituted C1-10 alkyl (e.g., C1-6 alkyl, unsubstituted C1-10 alkyl, or unsubstituted C1-6 alkyl); optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; -C(=O)Ra; and -C(=O)ORa; and each of R1, R2, R3, and R4is, independently, H; C1-10 alkyl (e.g., C1-6 alkyl); optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; -NO2; -ORa; -SRa; -N(Ra)2-3; -C(=O)Ra; -C(=O)ORa; -S(=O)2Ra; -S(=O)2ORa; -P(=O)Ra2; and -P(=O)(ORa)2; or any two adjacent groups selected from R1, R2, R3, and R4are joined to form an optionally substituted 3-6 membered ring, or an ion thereof; wherein each Ra is, independently, H; C1-10 alkyl (e.g., C1-6 alkyl); optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S.

[0141] In some embodiments, each of R9and R10is, independently, H, optionally substituted C1-10 alkyl (e.g., C1-6 alkyl), or -C(=O)ORa; and each of R1, R2, R3, and R4is, independently, H, halo, optionally substituted C1-10 alkyl (e.g., C1-6 alkyl), -NO2, -ORa, -SRa; -N(Ra)2-3, -C(=O)ORa, -S(=O)2ORa, - P(=O)Ra2 or -P(=0)(ORa)2; wherein each Rais, independently, H or optionally substituted C1-10 alkyl (e.g., C1-6 alkyl). In some embodiments, none of, any two of, any three of, any four of, any five of, or any six of R1, R2, R3, R4, R9, and R10are H.

[0142] In some embodiments, the oxidized or reduced mediator may be in salt form. Suitable salts include acid, e.g., Ch, or base addition salts, e.g., Na+.

[0143] In some embodiments, the mediator can include formula (Io)PATENT

[0144] Attorney Docket No. 51198-070W02

[0145]

[0146] (Io), or a salt thereof.

[0147] In some embodiments, the mediator can include formula (Ip)

[0148] H

[0149]

[0150] OOC

[0151] (Ip), or a salt thereof.

[0152] In some embodiments, the mediator can include formula (Iq)

[0153]

[0154] or a salt thereof.

[0155] In some embodiments, the mediator can include formula (Ir)

[0156] O

[0157]

[0158] O (Ir), or a salt thereof.

[0159] In some embodiments, the mediator can have a capacity fade rate, expressed as a percentage of decrease in capacity per cycle or per unit time. In some embodiments, fade rate can refer to the rate of loss of electrochemical capacity, efficiency, and / or activity of a mediator over successive redox and / or reaction cycles.

[0160] In some embodiments, the mediator can have a capacity fade rate in a range of about 0.01 vol% to about 1 vol% (e.g., about 0.01 vol% to about 1 vol%, about 0.02 vol% to about 1 vol%, about 0.03 vol% to about 1 vol%, about 0.04 vol% to about 1 vol%, about 0.05 vol% to about 1 vol%, about 0.075 vol% to about 1 vol%, about 0.1 vol% to about 1 vol%, about 0.125 vol% to about 1 vol%, about 0.15 vol% to about 1 vol%, about 0.2 vol% to about 1 vol%, about 0.25 vol% to about 1 vol%, about 0.3 vol% to about 1 vol%, about 0.35 vol% to about 1 vol%, about 0.4 vol% to about 1 vol%, about 0.5PATENT

[0161] Attorney Docket No. 51198-070W02

[0162] vol% to about 1 vol%, about 0.6 vol% to about 1 vol%, about 0.7 vol% to about 1 vol%, about 0.8 vol% to about 1 vol%, about 0.9 vol% to about 1 vol%, about 0.02 vol% to about 0.98 vol%, about 0.03 vol% to about 0.97 vol%, about 0.04 vol% to about 0.96 vol%, about 0.05 vol% to about 0.95 vol%, about 0.075 vol% to about 0.925 vol%, about 0.1 vol% to about 0.9 vol%, about 0.125 vol% to about 0.875 vol%, about 0.15 vol% to about 0.85 vol%, about 0.2 vol% to about 0.8 vol%, about 0.25 vol% to about 0.75 vol%, about 0.3 vol% to about 0.7 vol%, about 0.35 vol% to about 0.65 vol%, or about 0.4 vol% to about 0.6 vol%, e.g., about 0.01 vol%, about 0.02 vol%, about 0.03 vol%, about 0.04 vol%, about 0.05 vol%, about 0.075 vol%, about 0.1 vol%, about 0.125 vol%, about 0.15 vol%, about 0.2 vol%, about 0.25 vol%, about 0.3 vol%, about 0.35 vol%, about 0.4 vol%, about 0.5 vol%, about 0.6 vol%, about 0.7 vol%, about 0.8 vol%, about 0.9 vol%, or about 1 vol%) per day, inclusive of all values and ranges in between. In some embodiments, the capacity fade rate of the mediator can be at least about 0.01 vol%, at least about 0.02 vol%, at least about 0.03 vol%, at least about 0.04 vol%, at least about 0.05 vol%, at least about 0.1 vol%, at least about 0.2 vol%, at least about 0.3 vol%, at least about 0.3 vol%, at least about 0.4 vol%, at least about 0.4 vol%, at least about 0.5 vol%, at least about 0.6 vol%, at least about 0.7 vol%, at least about 0.8 vol%, at least about 0.9 vol%, or at least about 1 vol%, inclusive of all values and ranges in between. In some embodiments, the capacity fade rate of the mediator can be no more than about 1 vol%, no more than about 0.9 vol%, no more than about 0.8 vol%, no more than about 0.7 vol%, no more than about 0.6 vol%, no more than about 0.5 vol%, no more than about 0.4 vol%, no more than about 0.3 vol%, no more than about 0.2 vol%, no more than about 0.1 vol%, no more than about 0.05 vol%, no more than about 0.04 vol%, no more than about 0.03 vol%, no more than about 0.02 vol%, or no more than about 0.01 vol%, inclusive of all values and ranges in between. Combinations of the above-referenced capacity fade rate of the mediator are also possible (e.g., at least about 0.01 vol%, and no more than about 1 vol%, or at least about 0.1 vol% and no more than about 0.5 vol%), inclusive of all values and ranges therebetween. In some embodiments, the capacity fade rate of the mediator can be about 0.01 vol%, about 0.02 vol%, about 0.03 vol%, about 0.04 vol%, about 0.05 vol%, about 0.1 vol%, about 0.2 vol%, about 0.3 vol%, about 0.4 vol%, about 0.5 vol%, about 0.6 vol%, about 0.7 vol%, about 0.8 vol%, about 0.9 vol%, or about 1 vol%, inclusive of all values and ranges therebetween.

[0163] In some embodiments, the mediator can have a coulombic efficiency of at least about 90%. In some embodiments, the mediator can have a coulombic efficiency of at least about 91% at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99%, inclusive of all values and ranges in between.

[0164] In some embodiments, the mediator can have a standard redox potential of about -2 V to about 2 V (e.g., about -2.0 V to about 2.0 V, about -1.9 V to about 2.0 V, about -1.8 V to about 2.0 V, about -1.7 V to about 2.0 V, about -1.6 V to about 2.0 V, about -1.5 V to about 2.0 V, about -1.4 V to about 2.0 V, about -1.3 V to about 2.0 V, about -1.2 V to about 2.0 V, about -1.1 V to about 2.0 V, about -1 V to about 2.0 V, about -0.9 V to about 2.0 V, about -0.8 V to about 2.0 V, about -0.7 V to about 2.0 V, about -0.6 V to about 2.0 V, about -0.5 V to about 2.0 V, about -0.4 V to about 2.0 V, about -0.3 V to about 2.0 V, about -0.2 V to about 2.0 V, about -0.1 V to about 2.0 V, about 0 V to about 2.0 V, about 0.1 V to about 2.0 V, about 0.2 V to about 2.0 V, about 0.3 V to about 2.0 V, about 0.4 V to about 2.0PATENT

[0165] Attorney Docket No. 51198-070W02

[0166] V, about 0.5 V to about 2.0 V, about 0.6 V to about 2.0 V, about 0.7 V to about 2.0 V, about 0.8 V to about 2.0 V, about 0.9 V to about 2.0 V, about 1 V to about 2.0 V, about 1.1 V to about 2.0 V, about 1.2 V to about 2.0 V, about 1.3 V to about 2.0 V, about 1.4 V to about 2.0 V, about 1.5 V to about 2.0 V, about 1.6 V to about 2.0 V, about 1.7 V to about 2.0 V, about 1.8 V to about 2.0 V, about 1.9 V to about 2.0 V, about -1 .9 V to about 1.9 V, about -1.8 V to about 1.8 V, about -1.7 V to about 1.7 V, about -1.6 V to about 1.6 V, about -1.5 V to about 1.5 V, about -1.4 V to about 1.4 V, about -1.3 V to about 1.3 V, about -1 .2 V to about 1.2 V, about -1.1 V to about 1.1 V, about -1 V to about 1 V, about -0.9 V to about 0.9 V, about -0.8 V to about 0.8 V, about -0.7 V to about 0.7 V, about -0.6 V to about 0.6 V, about -0.5 V to about 0.5 V, about -0.4 V to about 0.4 V, about -0.3 V to about 0.3 V, about -0.2 V to about 0.2 V, about -0.1 V to about 0.1 V, about -2.0 V to about 1.9 V, about -2.0 V to about 1.8 V, about -2.0 V to about 1.7 V, about -2.0 V to about 1.6 V, about -2.0 V to about 1.5 V, about -2.0 V to about 1.4 V, about -2.0 V to about 1.3 V, about -2.0 V to about 1.2 V, about -2.0 V to about 1.1 V, about -2.0 V to about 1 V, about -2.0 V to about 0.9 V, about -2.0 V to about 0.8 V, about -2.0 V to about 0.7 V, about -2.0 V to about 0.6 V, about -2.0 V to about 0.5 V, about -2.0 V to about 0.4 V, about -2.0 V to about 0.3 V, about -2.0 V to about 0.2 V, about -2.0 V to about 0.1 V, about -2.0 V to about 0 V, about -2.0 V to about -0.1 V, about -2.0 V to about -0.2 V, about -2.0 V to about -0.3 V, about -2.0 V to about -0.4 V, about -2.0 V to about -0.5 V, about -2.0 V to about -0.6 V, about -2.0 V to about -0.7 V, about -2.0 V to about -0.8 V, about -2.0 V to about -0.9 V, about -2.0 V to about -1 V, about -2.0 V to about -1.1 V, about -2.0 V to about -1.2 V, about -2.0 V to about -1.3 V, about -2.0 V to about -1.4 V, about -2.0 V to about -1.5 V, about -2.0 V to about -1.6 V, about -2.0 V to about -1.7 V, about -2.0 V to about -1.8 V, or about -2.0 V to about -1.9 V, e.g., about -2.0 V, about -1.9 V, about - 1.8 V, about -1.7 V, about -1.6 V, about -1.5 V, about -1.4 V, about -1.3 V, about -1.2 V, about -1.1 V, about -1 V, about -0.9 V, about -0.8 V, about -0.7 V, about -0.6 V, about -0.5 V, about -0.4 V, about -0.3 V, about -0.2 V, about -0.1 V, about 0 V, about 0.1 V, about 0.2 V, about 0.3 V, about 0.4 V, about 0.5 V, about 0.6 V, about 0.7 V, about 0.8 V, about 0.9 V, about 1 V, about 1.1 V, about 1.2 V, about 1.3 V, about 1.4 V, about 1.5 V, about 1 .6 V, about 1.7 V, about 1.8 V, about 1.9 V, or about 2.0 V), inclusive of all values and ranges in between. In some embodiments, the standard redox potential of the mediator can be at least about -2 V, at least about -1 V, at least about -0.95 V, at least about -0.9 V, at least about -0.85 V, at least about -0.8 V, at least about -0.75 V, at least about -0.7 V, at least about -0.65 V, at least about -0.6 V, at least about -0.55 V, at least about -0.5 V, at least about -0.45 V, at least about -0.4 V, at least about -0.35 V, at least about -0.3 V, at least about -0.2 V, or at least about -0.1 V, at least about 0.1 V, at least about 0.2 V, at least about 0.3 V, at least about 0.4 V, at least about 0.5 V, at least about 0.6 V, at least about 0.7 V, at least about 0.8 V, at least about 0.9 V, at least about 1 V, at least about 2 V, inclusive of all values and ranges in between. In some embodiments, the standard redox potential of the mediator can be no more than about 2 V, no more than about 1 V, no more than about 0.5 v, no more than about 0.4 V, no more than about 0.3 V, no more than about 0.1 V, no more than about -0.2 V, no more than about -0.5 V, no more than about -0.55 V, no more than about -0.6 V, no more than about -0.65 V, no more than about -0.7 V, no more than about -0.75 V, no more than about -0.8 V, no more than about -0.85 V, no more than about -0.9 V, no more than about -0.95 V, or no more than about -0.99 V, or no more than about -2 V, inclusivePATENT

[0167] Attorney Docket No. 51198-070W02

[0168] of all values and ranges in between. Combinations of the above-referenced standard redox potential of the mediator are also possible (e.g., at least about -2 V, and no more than about 2 V, or at least about -0.95 V and no more than about 0.65 V), inclusive of all values and ranges therebetween. In some embodiments, the standard redox potential of the mediator can be about -2 V, about -0.99 V, about -0.95 V, about -0.9 V, about -0.8 V, about -0.7 V, about -0.6 V, about -0.45, about -0.4 V, about -0.35 V, about -0.3 V, about -0.25 V, about -0.2 V, about -0.15 V, about -0.1 V, about 0.5 V, about 1 V, about 1.5 V, or about 2 V, inclusive of all values and ranges therebetween.

[0169] In some embodiments, the reduced mediator can be configured to cause hydrogenation of a reactant. The reactant can include an unsaturated compound including, but not limited to, at least one of an alkene (terminal, internal, cyclic, acyclic, substituted, and / or conjugated), an alkyne (terminal or internal), a carbonyl containing compounds (such as a ketone, an aldehyde, an ester, an amide, an anhydride, and an a,p unsaturated carbonyl compound), a reducible nitrogen containing compound such as an azo, a hydroxamic acid, a hydroxyl amine, an N-oxide, a nitrite (RONO species), a nitro (R-NO2), a nitroso (R-NO), a nitrene precursor (R-N:), a nitrile (R-C=N), or any combination thereof. In some embodiments, the reducible functional group of such a nitrogen containing compound can be referred to as reducible nitrogen.

[0170] In some embodiments, the hydrogen transfer occurs through intermediate species, for example, a catalyst. Hydrogen transfer can proceed through a direct chemical reaction, proton-coupled electron transfer, radical pathways, or other suitable hydrogenation mechanisms.

[0171] In some embodiments, an electrochemical cell can reduce the mediator (also referred to as Q) via application of an electrical potential and form the reduced mediator (also referred to as mediator in a reduced state or Qred). The reduced mediator is in a lower oxidation state than the mediator in the original state or an oxidized mediator.

[0172] In some embodiments, the electrochemical cell can include an electrochemical flow cell. In some embodiments, the electrochemical cell can include a cathode, an anode, and a separator membrane. The reduction of the mediator occurs at the cathode. In some embodiments, the cathode is contacted with the aqueous phase while an electrical potential is applied. In some embodiments, the aqueous phase includes the mediator. In some embodiments, an oxygen evolution reaction (OER) and / or hydrogen oxidation reaction (HOR) can occur at the anode.

[0173] In some embodiments, the aqueous phase including the reduced mediator can be transported to a second unit, where the aqueous phase including the reduced mediator can contact a nonaqueous phase including the reactant (for example, an unsaturated compound) in presence of a solid phase including a catalyst. Since the solid phase includes the catalyst, both terms can be used interchangeably, unless otherwise apparent from context, and a single reference number may be used to denote either the catalyst or the solid phase throughout the specification.

[0174] In some embodiments, the aqueous phase including the reduced mediator can be transported to the second unit in batch mode or in a continuous flow. In some embodiments, the nonaqueous phase, including the reactant can be transported to the second unit (e.g., reactor), independently of thePATENT

[0175] Attorney Docket No. 51198-070W02

[0176] aqueous phase. In some embodiments, the solid phase including the catalyst can be transported to the second unit (e.g., reactor), independently or along with the aqueous phase or the nonaqueous phase.

[0177] In some embodiments, the aqueous phase, the nonaqueous phase, and the solid phase form a first mixture. In some embodiments, the contacting of the aqueous phase, the nonaqueous phase, and the solid phase occurs in the reactor. In some embodiments, the contacting of the aqueous phase, the nonaqueous phase, and the solid phase can be facilitated with an agitator. In some embodiments, the agitator can be configured to agitate the aqueous phase, the nonaqueous phase, and the solid phase, (collectively referred to as the “first mixture”) thereby enhancing the interphase contact among the three phases.

[0178] In some embodiments, contact of the aqueous phase, the nonaqueous phase, and the solid phase can be facilitated by agitation at an agitating rate sufficient to achieve enhanced interface between the aqueous phase, the solid phase, and the nonaqueous phase for the desirable reaction rate. In some embodiments, the reaction can occur at a stirring rate of about 500 rpm to about 4,000 rpm (e.g., about 500 rpm to about 4000 rpm, about 600 rpm to about 4000 rpm, about 700 rpm to about 4000 rpm, about 800 rpm to about 4000 rpm, about 900 rpm to about 4000 rpm, about 1000 rpm to about 4000 rpm, about 1200 rpm to about 4000 rpm, about 1400 rpm to about 4000 rpm, about 1600 rpm to about 4000 rpm, about 1800 rpm to about 4000 rpm, about 2000 rpm to about 4000 rpm, about 2200 rpm to about 4000 rpm, about 2400 rpm to about 4000 rpm, about 2600 rpm to about 4000 rpm, about 2800 rpm to about 4000 rpm, about 3000 rpm to about 4000 rpm, about 3200 rpm to about 4000 rpm, about 3400 rpm to about 4000 rpm, about 3600 rpm to about 4000 rpm, about 3800 rpm to about 4000 rpm, about 600 rpm to about 3900 rpm, about 700 rpm to about 3800 rpm, about 800 rpm to about 3700 rpm, about 900 rpm to about 3600 rpm, about 1000 rpm to about 3500 rpm, about 1200 rpm to about 3300 rpm, about 1400 rpm to about 3100 rpm, about 1600 rpm to about 2900 rpm, about 1800 rpm to about 2700 rpm, about 2000 rpm to about 2500 rpm, or about 2200 rpm to about 2300 rpm, e.g., about 500 rpm, about 600 rpm, about 700 rpm, about 800 rpm, about 900 rpm, about 1000 rpm, about 1200 rpm, about 1400 rpm, about 1600 rpm, about 1800 rpm, about 2000 rpm, about 2200 rpm, about 2400 rpm, about 2600 rpm, about 2800 rpm, about 3000 rpm, about 3200 rpm, about 3400 rpm, about 3600 rpm, about 3800 rpm, or about 4000 rpm), inclusive of all values and ranges in between. In some embodiments, the mixing rate can be at least about 500 rpm, at least about 1 ,000 rpm, at least about 1 ,200 rpm, at least about 1 ,400 rpm, at least about 1 ,600 rpm, at least about 1 ,800 rpm, at least about 1 ,900 rpm, at least about 2,000 rpm, at least about 2,100 rpm, at least about 2,200 rpm, at least about 2,300 rpm, at least about 2,400 rpm, at least about 2,500 rpm, at least about 2,600 rpm, at least about 2,700 rpm, at least about 2,800 rpm, at least about 2,900 rpm, at least about 3,000 rpm, at least about 3,100 rpm, at least about 3,200 rpm, at least about 3,300 rpm, at least about 3,400 rpm, at least about 3,500 rpm, at least about 3,600 rpm, at least about 3,700 rpm, at least about 3,800 rpm, at least about 3,900 rpm, or at least about 4,000 rpm, inclusive of all values and ranges in between. In some embodiments, the agitating rate can be no more than about 4,000 rpm, no more than about 3,900 rpm, no more than about 3,800 rpm, no more than about 3,700 rpm, no more than about 3,600 rpm, no more than about 3,500 rpm, no more than about 3,400 rpm, no more than aboutPATENT

[0179] Attorney Docket No. 51198-070W02

[0180] 3,300 rpm, no more than about 3,200 rpm, no more than about 3,100 rpm, no more than about 3,000 rpm, no more than about 2,800 rpm, no more than about 2,700 rpm, no more than about 2,600 rpm, no more than about 2,500 rpm, no more than about 2,400 rpm, no more than about 2,300 rpm, no more than about 2,200 rpm, no more than about 2,000 rpm, no more than about 1 ,900 rpm, no more than about 1 ,800 rpm, no more than about 1 ,600 rpm, no more than about 1 ,400 rpm, no more than about 1 ,200 rpm, no more than about 1 ,000 rpm, or no more than about 500 rpm, inclusive of all values and ranges in between. Combinations of the above-referenced agitating rates are also possible (e.g., at least about 500 rpm, and no more than about 4,000 rpm, or at least about 2,000 rpm and no more than about 3,000 rpm), inclusive of all values and ranges therebetween. In some embodiments, the agitating rate can be about 500 rpm, about 1 ,000 rpm, about 1 ,200 rpm, about 1 ,400 rpm, about 1 ,600 rpm, about 1 ,800 rpm, about 2,000 rpm, about 2,200 rpm, about 2,400 rpm, about 2,600 rpm, about 2,800 rpm, about 3,000 rpm, about 3,200 rpm, about 3,400 rpm, about 3,600 rpm, about 3,800 rpm, or about 4,000 rpm, inclusive of all values and ranges therebetween.

[0181] In some embodiments, the duration of the contacting for the hydrogenation reaction can be in a range of about 1 min to about 24 hours (e.g., about 1 min to about 24 hours, about 2 min to about 24 hours, about 3 min to about 24 hours, about 4 min to about 24 hours, about 5 min to about 24 hours, about 10 min to about 24 hours, about 15 min to about 24 hours, about 20 min to about 24 hours, about 30 min to about 24 hours, about 40 min to about 24 hours, about 50 min to about 24 hours, about 1 hour to about 24 hours, about 2 hours to about 24 hours, about 3 hours to about 24 hours, about 4 hours to about 24 hours, about 5 hours to about 24 hours, about 10 hours to about 24 hours, about 15 hours to about 24 hours, or about 20 hours to about 24 hours, e.g., about 1 min, about 2 min, about 3 min, about 4 min, about 5 min, about 10 min, about 15 min, about 20 min, about 30 min, about 40 min, about 50 min, about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 10 hours, about 15 hours, about 20 hours, or about 24 hours), inclusive of all values and ranges in between. In some embodiments, the duration of the contacting for the reaction can be at least about 1 min, at least about 10 min, at least about 30 min, at least about 1 hr, at least about 2 hrs, at least about 3 hrs, at least about 4 hrs, at least about 5 hrs, at least about 6 hrs, at least about 7 hrs, at least about 8 hrs, at least about 9 hrs, at least about 10 hrs, at least about 12 hrs, at least about 14 hrs, at least about 16 hrs, at least about 18 hrs, at least about 20 hrs, at least about 22 hrs, or at least about 24 hrs, inclusive of all values and ranges in between. In some embodiments, the duration of the contacting for the reaction can be no more than about 24 hrs, no more than about 22 hrs, no more than about 20 hrs, no more than about 18 hrs, no more than about 16 hrs, no more than about 14 hrs, no more than about 12 hrs, no more than about 10 hrs, no more than about 9 hrs, no more than about 8 hrs, no more than about 7 hrs, no more than about 6 hrs, no more than about 7 hrs, no more than about 6 hrs, no more than about 5 hrs, no more than about 4 hrs, no more than about 3 hrs, no more than about 2 hrs, no more than about 1 hrs, no more than about 30 min, no more than about 10 min, or no more than about 1 min, inclusive of all values and ranges in between. Combinations of the above-referenced duration of the contacting for the reaction are also possible (e.g., at least about 1 min, and no more than about 24 hrs, or at least about 4 hrs and no more than about 8 hrs), inclusive of all values and ranges therebetween. In some embodiments, the duration of the contacting for thePATENT

[0182] Attorney Docket No. 51198-070W02

[0183] reaction can be about 1 min, about 10 min, about 30 min, about 1 hr, about 2 hrs, about 3 hrs, about 4 hrs, about 5 hrs, about 6 hrs, about 7 hrs, about 8 hrs, about 9 hrs, about 10 hrs, about 12 hrs, about 14 hrs, about 16 hrs, about 18 hrs, about 20 hrs, about 22 hrs, or about 24 hrs, inclusive of all values and ranges therebetween.

[0184] In some embodiments, the volumetric ratio of the aqueous solution to the nonaqueous solution can be in range of about 1 :1 to about 3:1. In some embodiments, the volumetric ratio of the aqueous solution to the nonaqueous solution can be at least about 1 :1 , at least about 1.2:1 , at least about 1 .4:1 , at least about 1.6:1 , at least about 1.8:1 , at least about 2:1 , at least about 2.2:1 , at least about 2.4:1 , at least about 2.6:1 , at least about 2.8:1 , or at least about 3:1 , inclusive of all values and ranges in between. In some embodiments, the volumetric ratio of the aqueous solution and the nonaqueous solution can be no more than about 3:1 , no more than about 2.8:1 , no more than about 2.6:1 , no more than about 2.4:1 , no more than about 2.2:1 , no more than about 2:1 , no more than about 1.8:1 , no more than about 1 .6:1 , no more than about 1 .4:1 , no more than about 1.2:1 , or no more than about 1 :1 , inclusive of all values and ranges in between. Combinations of the above-referenced volumetric ratio of the aqueous solution to the nonaqueous solution are also possible (e.g., at least about 1 :1 , and no more than about 3:1 , or at least about 1.5:1 and no more than about 2:1), inclusive of all values and ranges therebetween. In some embodiments, the volumetric ratio of the aqueous solution to the nonaqueous solution can be about 1 :1 , about 1.2:1 , about 1.4:1 , about 1.6:1 , about 1.8:1 , about 2:1 , about 2.2:1 , about 2.4:1 , about 2.6:1 , about 2.8:1 , or about 3:1 , inclusive of all values and ranges therebetween.

[0185] In some embodiments, the volumetric ratio can be flipped. In some embodiments, the volumetric ratio of the nonaqueous solution to the aqueous solution can be in range of about 1 :1 to about 3:1. In some embodiments, the volumetric ratio of the nonaqueous solution to the aqueous solution can be at least about 1 :1 , at least about 1.2:1 , at least about 1.4:1 , at least about 1.6:1 , at least about 1.8:1 , at least about 2:1 , at least about 2.2:1 , at least about 2.4:1 , at least about 2.6:1 , at least about 2.8:1 , or at least about 3:1 , inclusive of all values and ranges in between. In some embodiments, the volumetric ratio of the nonaqueous solution to the aqueous solution can be no more than about 3:1 , no more than about 2.8:1 , no more than about 2.6:1 , no more than about 2.4:1 , no more than about 2.2:1 , no more than about 2:1 , no more than about 1.8:1 , no more than about 1.6:1 , no more than about 1.4:1 , no more than about 1.2:1 , or no more than about 1 :1 , inclusive of all values and ranges in between. Combinations of the above-referenced volumetric ratio of the nonaqueous solution to the aqueous solution are also possible (e.g., at least about 1 :1 , and no more than about 3:1 , or at least about 1.5:1 and no more than about 2:1), inclusive of all values and ranges therebetween. In some embodiments, the volumetric ratio of the nonaqueous solution to the aqueous solution can be about 1 :1 , about 1.2:1 , about 1.4:1 , about 1.6:1 , about 1 .8:1 , about 2:1 , about 2.2:1 , about 2.4:1 , about 2.6:1 , about 2.8:1 , or about 3:1 , inclusive of all values and ranges therebetween.

[0186] In some embodiments, a concentration of the reduced mediator in the aqueous solution can be in a range of about 5 mol% to about 20 mol% (e.g., about 5 mol% to about 20 mol%, about 6 mol% to about 20 mol%, about 7 mol% to about 20 mol%, about 8 mol% to about 20 mol%, about 9 mol% toPATENT

[0187] Attorney Docket No. 51198-070W02

[0188] about 20 mol%, about 10 mol% to about 20 mol%, about 11 mol% to about 20 mol%, about 12 mol% to about 20 mol%, about 13 mol% to about 20 mol%, about 14 mol% to about 20 mol%, about 15 mol% to about 20 mol%, about 16 mol% to about 20 mol%, about 17 mol% to about 20 mol%, about 18 mol% to about 20 mol%, about 19 mol% to about 20 mol%, about 6 mol% to about 19 mol%, about 7 mol% to about 18 mol%, about 8 mol% to about 17 mol%, about 9 mol% to about 16 mol%, about 10 mol% to about 15 mol%, about 11 mol% to about 14 mol%, or about 12 mol% to about 13 mol%), inclusive of all values and ranges in between. In some embodiments, the concentration of the reduced mediator can be at least about 5 mol%, at least about 6 mol%, at least about 7 mol%, at least about 8 mol%, at least about 9 mol%, at least about 10 mol%, at least about 11 mol%, at least about 12 mol%, at least about 13 mol%, at least about 14 mol%, at least about 15 mol%, at least about 16 mol%, at least about 17 mol%, at least about 18 mol%, at least about 19 mol%, or at least about 20 mol%, inclusive of all values and ranges in between. In some embodiments, the concentration of the reduced mediator can be no more than about 20 mol%, no more than about 19 mol%, no more than about 18 mol%, no more than about 17 mol%, no more than about 16 mol%, no more than about 15 mol%, no more than about 14 mol%, no more than about 13 mol%, no more than about 12 mol%, no more than about 11 mol%, no more than about 10 mol%, no more than about 9 mol%, no more than about 8 mol%, no more than about 7 mol%, no more than about 6 mol%, or no more than about 5 mol%, inclusive of all values and ranges in between. Combinations of the above-referenced concentration of the reduced mediator are also possible (e.g., at least about 5 mol%, and no more than about 20 mol%, or at least about 10 mol% and no more than about 14 mol%), inclusive of all values and ranges therebetween. In some embodiments, the concentration of the reduced mediator can be about 5 mol%, about 6 mol%, about 7 mol%, about 8 mol%, about 9 mol%, about 10 mol%, about 11 mol%, about 12 mol%, about 13 mol%, about 14 mol%, about 15 mol%, about 16 mol%, about 17 mol%, about 18 mol%, about 19 mol%, or about 20 mol%, inclusive of all values and ranges therebetween.

[0189] In some embodiments, the concentration of the mediator can be from about 0.1 M to about 1 M, inclusive of all values and ranges in between. In some embodiments, the concentration of the mediator in can be at least about 0.1 M, at least about 0.2 M, at least about 0.3 M, at least about 0.4 M, at least about 0.5 M, at least about 0.6 M, at least about 0.7 M, at least about 0.8 M, at least about 0.9 M, or at least about 1 M, inclusive of all values and ranges in between. In some embodiments, the concentration of the mediator in can be no more than about 1 M, no more than about 0.9 M, no more than about 0.8 M, no more than about 0.7 M, no more than about 0.6 M, no more than about 0.5 M, no more than about 0.4 M, no more than about 0.3 M, no more than about 0.2 M, or no more than about 0.1 M, inclusive of all values and ranges in between. Combinations of the above-referenced concentrations of the mediator are also possible (e.g., at least about 0.1 M, and no more than about 1 M, or at least about 0.2 M and no more than about 0.3 M), inclusive of all values and ranges therebetween. In some embodiments, the concentration of the mediator can be about 0.1 M, about 0.2 M, about 0.3 M, about 0.4 M, about 0.5 M, about 0.6 M, about 0.7 M, about 0.8 M, about 0.9 M, or about 1 M, inclusive of all values and ranges therebetween.PATENT

[0190] Attorney Docket No. 51198-070W02

[0191] The catalyst can facilitate hydrogen transfer, adsorption, desorption, or interfacial localization phenomena. Without wishing to be bound by any particular theory, hydrogen species or electrons associated with the reduced mediator or aqueous phase can transfer to the surface of the catalyst when the electrostatic potential of the mediator is more negative than an underpotential deposition threshold. In some embodiments, the hydrogen species transferred to the catalyst surface can be referred to as surface associated hydrogen species.

[0192] In some embodiments, the catalyst can include one or more metals, metal oxides, metal sulfides, supported catalysts, porous catalysts, surface-modified catalysts, or combinations thereof. Suitable metals can include but are not limited to palladium (Pd), platinum (Pt), nickel (Ni), cobalt (Co), iron (Fe), rhodium (Rh), ruthenium (Ru), iridium (Ir), and copper (Cu). In some embodiments, the catalyst can include a porous metal catalyst such as Raney nickel or Raney copper. Any combination or alloy of the foregoing can also be used.

[0193] In some embodiments, the catalyst can be carried on or supported on a support material. Suitable supports can include, for example, carbon, activated carbon, graphite, carbon black, silica, alumina, titania, zirconia, zeolites, or combinations thereof. In certain embodiments, the support can include carbon, which can provide high surface area and enhanced dispersion of the catalytic metal.

[0194] In other embodiments, the catalyst can include a porous nickel or copper material prepared by leaching aluminum from a nickel-aluminum alloy or copper-aluminum alloy. Leaching can be performed using aqueous hydroxides (e.g., NaOH or KOH) to selectively remove aluminum, producing a high-surface-area, sponge-like metal structure.

[0195] In some embodiments, the catalyst can include a Janus solid catalyst. As used herein, a “Janus catalyst” or “Janus solid catalyst” refers to a solid phase including a catalyst and having at least two distinct regions or surfaces having different chemical and / or physical properties which can be configured to interact with different surrounding phases. In some embodiments, the solid phase is amphipathic. In some embodiments, the amphipathic behavior of solid phase can be inherent and / or introduced through surface modification, functionalization, coating, or attachment of chemical groups. In some embodiments, an amphipathic solid phase can be capable of interacting with both polar, e.g., aqueous, and non-polar environments. In some embodiments, the amphipathic solids phase can be localized at an interface between the aqueous phase and the nonaqueous phase.

[0196] In some embodiments, the solid phase can include a surface modifier configured to alter the surface properties in a homogeneous or heterogeneous way. In some embodiments, the surface modified solid phase can be amphipathic. In some embodiments, the surface modified solid phase can be configured to localize at an interface between the aqueous phase and the nonaqueous phase. In some embodiments, the surface modifier can modify the surface of the solid phase such that the solid phase has at least two distinct regions, including a first region and a second region. The first region can differ from the second region in chemical composition, physical properties, surface functionality, wettability, catalytic activity, and / or interaction with surrounding phases. The first region and the second region can perform different functions including but not limited to electron transfer, proton transfer, hydrogen association., adsorption of reactants, release of products, stabilization of reactionPATENT

[0197] Attorney Docket No. 51198-070W02

[0198] intermediates, mediation of mass or charge transport, phase transfer between immiscible phases, redox mediation, regulation of reaction selectivity, and / or regeneration of catalytic activity.

[0199] In some embodiments, the first region and / or the second region can exhibit different wettability characteristics, including hydrophilic, hydrophobic, and / or amphiphilic behavior. The first region can preferentially contact or be wetted by the aqueous phase including the reduced mediator. The second region preferentially can contact or be wetted by the nonaqueous phase, including the reactant. For example, the first region of the catalyst can interact with the mediator in any reduction reduced state. For example, the second region can interact with the reactant.

[0200] In some embodiments, the solid phase can include multiple first region and second region. The distinct regions can be spatially separated, adjacent, partially overlapping, and / or oriented such that the distinct regions can preferentially interact with different phases, reactants, and / or intermediates. The distinct regions can be oriented relative to a direction of fluid flow, an electric field, a concentration gradient, and / or a phase boundary. The regions can be arranged such that each region preferentially contacts a different phase while remaining in functional communication with another region.

[0201] In some embodiments, the solid phase described herein can be stabilized at or near the interface between the aqueous phase and the nonaqueous phase. The catalyst can facilitate transportation of the hydrogen species, and / or electro-proton pair, from the aqueous phase into the nonaqueous phase. The catalyst described herein can significantly reduce the phase transfer issue and facilitate transfer of hydrogen species from the mediator to the reactant.

[0202] In some embodiments, the solid phase can include a surface modifier. In some embodiments, the solid phase can include polytetrafluoroethylene (PTFE). In some embodiments, the surface modifier can include, but is not limited to, fluoropolymers, for example, polyvinylidene fluoride (PVDF), fluorinated ethylene propylene (FEP), perfluoro alkoxy polymer (PFA), ethylene tetrafluoroethylene (ETFE), fluoroalkyl silanes (e.g., perfluoroalkyltrichlorosilanes), perfluoropolyethers (PFPEs), TEFLON®-like fluorinated coatings. In some embodiments, the surface modifier can be silane based, for example, hydrophobic silanes such as trimethylsilyl (TMS) groups, octyltrichlorosilane (OTS), hexamethyldisilazane (HMDS), fluoroalkyl silanes. The silane-based surface modifier can include hydrophilic silanes such as aminosilanes, carboxy-functional silanes, hydroxyl-functional silanes. In some embodiments, the surface modifier can include long chain organic coatings, for example, stearic acid, oleic acid, linoleic acid, alkyl thiols, alkyl phosphonic acids. In some embodiments, the surface modifier can include a metal oxide surface layer, for example, silica, alumina, titania, zirconia. In some embodiments, the surface modifier can include surfactants and amphiphilic molecules, for example, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), TWEEN® surfactants (polysorbate), or SPAN® surfactants (sorbitan esters). In some embodiments, the surface modifier can include inorganic surface modifiers, for example, phosphates, phosphonates, sulfates, sulfonates, or layered double hydroxide coatings. Surface modifiers may also include organic groups like carboxylates.PATENT

[0203] Attorney Docket No. 51198-070W02

[0204] In some embodiments, the surface phase can be provided in form of a powder, flakes, microparticles, nanoparticles, and / or a dispersion. In some embodiments, the surface modifier can be applied to the catalyst to partially or completely coat the catalyst. The surface modifier, for example PTFE, can be present as a continuous coating, a discontinuous patch-type layer, or as individual domains distributed across the surface.

[0205] In some embodiments, surface modification, for example PTFE coating, can reduce the surface energy of the solid phase, impart hydrophobic characteristics, and facilitate partial or complete localization of the catalyst at an interface between an aqueous phase and a nonaqueous phase. In some embodiments, the surface modifier (e.g., PTFE) can enhance compatibility with nonaqueous phase, improve catalyst mobility at phase boundaries, and / or promote interfacial catalysis where both aqueous and nonaqueous components participate in the reaction.

[0206] In some embodiments, the surface modification can occur via ball milling. Ball milling can mechanically couple PTFE to the catalyst through repeated impact forces that promote adhesion, embed PTFE particles into surface asperities, and / or distribute PTFE across high-surface-area regions of the catalyst. The milling parameters — such as rotation speed, milling time, ball-to-material ratio, and milling atmosphere — can be adjusted to control the extent of surface coverage or hydrophobicity. In certain embodiments, the ball milling can be carried out in the presence of a liquid carrier or dispersant to improve the uniformity of PTFE deposition. In some embodiments, the surface modifier can be incorporated onto the surface of the catalyst via grafting, electrostatic or mechanical fixation, thermal lamination, plasma-associated PTFE deposition, PTFE dispersion coating, or any other suitable method.

[0207] The solid phase including the catalyst described herein can improve stability, reduce aggregation, and / or alter phase affinity. The solid phase including the catalyst described herein can enhance a collision frequency between the aqueous phase, including the aqueous mediator and the nonaqueous phase including the reactant, thereby significantly improve mass transport, increase interfacial localization, reduce waste generation, and / or improve selective hydrogenation. The solid phase including the catalyst described herein can provide advantages with respect to electrochemical efficiency.

[0208] In some embodiments, upon contact between the nonaqueous phase and the catalyst, the surface associated hydrogen species on the catalyst surface can react with the reactant, for example, unsaturated compound, thereby forming a hydrogenated product. In some embodiments, the reaction can include hydrogenation. In some embodiments, the hydrogenation can proceed via electron coupled proton transfer (ECPT), proton-coupled electron transfer (POET), hydride transfer, atomic hydrogen transfer, heterolytic or homolytic hydrogen activation, surface-mediated pathways, sequential protonation and reduction, or combinations thereof. In some embodiments, hydrogenation can proceed via one or more of the mentioned mechanisms, alone or in combination, and the systems described herein are not limited to any particular mechanistic pathway.

[0209] As used herein, the phrase “transfer of a hydrogen species” can include any chemical process by which a hydrogen equivalent (H°, FT, H+, or an electronically coupled proton / electron pair) is deliveredPATENT

[0210] Attorney Docket No. 51198-070W02

[0211] to a reactant. Such process can occur via one or more mechanistic pathways that results in delivery of hydrogen to a substrate (or reactant), including but not limited to concerted or stepwise ECPT, POET, atomic hydrogen transfer, heterolytic or homolytic hydrogen activation, surface-mediated pathways, and / or sequential protonation and reduction. No particular mechanistic pathway is required unless explicitly stated.

[0212] In some embodiments, during the transfer of a hydrogen species, the reduced mediator donates a hydrogen equivalent ( H°, FT, H+, or an electronically coupled proton / electron pair) or electron to the reactant, either directly or via the catalyst. As a consequence of this transfer, the mediator can undergo oxidation and be converted to an oxidized mediator. In some embodiments, upon transferring the hydrogen species or electron (or reducing equivalent), the mediator can be converted from its reduced form to a partially or fully oxidized form.

[0213] In some embodiments, oxidation of the reduced mediator can occur at the catalyst surface via homogeneous electron-transfer pathways in either the aqueous or nonaqueous phase. In some embodiments, oxidation of the reduced mediator can occur through interfacial electron- or proton-mediated processes. The specific mechanistic pathway is not limiting and can involve electron-proton transfer, hydrogen-atom transfer, or hydride / proton sequences. In some embodiments, the oxidized mediator can cycle between multiple oxidation states.

[0214] In some embodiments, the mediator can be regenerated to the original state of reduction. In some embodiments, the mediator can go through multiple cycles of reduction and oxidization. Therefore, the systems and methods described herein can significantly reduce waste material, improve hydrogenation efficiency, reduce cost, and / or be more environmentally friendly compared to the traditional methods of hydrogenation.

[0215] The system can further include a third unit, for example, a separator configured to separate the solid phase, the aqueous phase, and the nonaqueous phase. In some embodiments, the first unit, the second unit, and the third unit can be configured to be separated from one another or connected to one another. In some embodiments, the first unit, the second unit, and the third unit can be selectively separable or connectable. In some embodiments, the method can be carried out in batch or via a continuous flow in the system.

[0216] In some embodiments, the third unit can include one or more separators. In some embodiments, phase separation can be accomplished by gravity settling, centrifugation, membrane-based separation, and / or other liquid-liquid separation techniques. In some embodiments, the system can include a first separator and a second separator.

[0217] The first separator can include a solid-liquid separator, and the second separator can include a liquidliquid separator. In some embodiments, the first separator can separate the solid phase from the first mixture, thereby forming a second mixture including the aqueous phase and the nonaqueous phase. In some embodiments, the second separator can separate the aqueous phase from the second mixture.PATENT

[0218] Attorney Docket No. 51198-070W02

[0219] In some embodiments, the separated solid phase can be recirculated to the reactor to enable continuous or semi-continuous hydrogenation process. Recirculation can occur through one or more conduits, pumps, or fluid transfer pathways to transport the solid phase. The separated solid phase can be recirculated back to at least one of the reactor, a catalyst holding chamber, the aqueous phase, or the nonaqueous phase. In some embodiments, the system can facilitate hydrogenation of the reactant without separation of the solid phase from the reaction mixture. In some embodiments, a particulate solid phase having an average particle size below a threshold selected to prevent obstruction of conduits, pumps, or other fluid communication components can be retained within the reactor throughout operation. Such size control can enable continuous or semi-continuous processing while maintaining catalyst availability and avoiding mechanical fouling. In some embodiments, the separated solid phase can be recovered via downstream processes before recirculation to the reactor.

[0220] In some embodiments, the oxidized mediator can be recirculated back to the electrochemical cell. The mediator after oxidation can be available for repeated reduction during subsequent cycles and enable continuous or semi-continuous hydrogenation of the unsaturated compound.

[0221] Following formation of the hydrogenated product, the product can be directed to a purification unit to recover the hydrogenated product, remove residual solvent, or conduct an additional post-processing operation. In some embodiments, the hydrogenated product can be separated from the nonaqueous phase using any suitable separation technique. The nonaqueous phase including the hydrogenated product can undergo additional processing steps such as solvent removal, distillation, or chromatographic purification, depending on the desired purity and formulation.

[0222] After the hydrogenation step, the hydrogenated product resides predominantly in the nonaqueous phase and can be isolated by separating the nonaqueous phase from the other phases. The isolated nonaqueous phase containing the product can then be directed to a purification unit to recover the product, remove residual solvent, or conduct additional post-processing operations.

[0223] The methods described herein can 1) enable hydrogenation of unsaturated compounds and significantly reduce the byproducts of the hydrogenation reaction; 2) confine reduction of the mediator to the aqueous phase in an independent module, for example, the electrochemical cell; and / or 3) reduce additional byproducts and impurities. Moreover, the nonaqueous phase can serve as a reservoir for the saturated product, enabling operation at high concentrations and facilitating separation and / or purification of the saturated product from other components.

[0224] In addition, the present disclosure can enable independent or semi-dependent optimization of mass transport of ions, electrons, and / or reactants within different phases of a three phase hydrogenation system. This system can provide significantly more control over the electrochemical process occurring in the aqueous phase, and hydrogenation reaction occurring in the nonaqueous phase. Such system can improve control over kinetics of hydrogenation reaction, selectivity, and / or conversion by reducing mass transport limitations, minimizing competing reactions, and enable more efficient utilization of catalyst and electrochemical components.PATENT

[0225] Attorney Docket No. 51198-070W02

[0226] Embodiments described herein can facilitate hydrogenation reaction in ambient conditions without molecular hydrogen. Systems and methods described herein can reduce energy consumption, material usage, waste generation, thereby supporting environmentally favorable electrochemical processes suitable for industrial implementation. The mediators described herein can be regenerated and recirculated to the electrochemical cell for further reduction.

[0227] Systems and methods described herein can enable separation of the electrochemical reduction of the mediator from the hydrogenation of the unsaturated compound. By separating these two processes, the systems and methods described herein can significantly reduce the kinetic constraints and safety considerations associated with traditional high pressure molecular hydrogen protocols and direct organic electrosynthesis.

[0228] Without wishing to be bound by theory, driving force for hydrogenation can be influenced by the ability of the mediator to provide a potential sufficient to exceed the underpotential deposition threshold (Vupd) and thereby promote hydrogen uptake within the catalyst lattice. Mediators having more negative redox potentials can induce greater lattice expansion and are observed to provide faster reaction rates across a range of the reactant concentration.

[0229] Integration of a water soluble mediator and an engineered catalyst of a “Janus” type, can create a highly efficient system for hydrogenation of reactants. The systems, methods, and components described herein can allow separated optimization of mass transport of ions, electrons, and / or reactants in each phase with improved control of reaction kinetics. The systems, methods, and components described herein can allow enhanced control of hydrogenation activity via electrochemical tuning of the mediator’s redox potential.

[0230] In some embodiments, separating the electrochemical reduction of the mediator from the catalytic hydrogenation step can enable flexible operation with variable electricity inputs. Such configuration can allow the system to function as a chemical energy storage intermediate through the reversible cycling of the mediator.

[0231] The term “reactor” refers to any conduit, vessel, enclosure, zone, module, or system configured to contain and facilitate a chemical reaction. A reactor may provide controlled conditions such as temperature, pressure, mixing, flow, phase contact, or catalyst exposure. The reactor can include batch, semi-batch, flow, or continuous reactors, and may be constructed with any geometry or materials suitable for the intended reaction environment. The term “reactor” can include single-phase or multiphase systems, and can include additional components such as inlets, outlets, stirrers, baffles, heating or cooling elements, and internal or external catalyst supports. A reactor can be used to combine solid phase, aqueous phase, and / or nonaqueous phase. A reactor can be used to contact solid phase, aqueous phase, and / or nonaqueous phase. No particular scale, geometry, or mode of operation is required unless explicitly stated. The term “reactor” can refer to any physical location in which hydrogenation takes place. A reactor can include an interfacial region between an aqueous phase, and a nonaqueous phase wherein reactants are transformed (e.g., hydrogenated). Reactor can describe the operative space in which hydrogenation occurs, regardless of scale and structure.PATENT

[0232] Attorney Docket No. 51198-070W02

[0233] The term “hydrogenation” refers to a process by which hydrogen atoms, protons, hydrides, or reducing equivalents derived from hydrogen are incorporated into a compound. In other words, “hydrogenation” refers to a chemical transformation in which one or more atoms of hydrogen are added to a compound. In some embodiments, hydrogenation results in reduction of the compound. In some embodiments, hydrogenation can include partial or full electrochemical reduction of a mediator, resulting in incorporation of hydrogen atoms into the mediator or formation of a hydrogenated form of the mediator. Hydrogenation may include partial or complete reduction of an unsaturated compound, including without limitation, carbon-carbon double bonds, carbon-carbon triple bonds, carbonheteroatom multiple bonds (e.g., C=O, C=N, ON), an aldehyde, a ketone, or other ir-bonded or electron-deficient functional groups capable of accepting hydrogen. Hydrogenation can also include partial or complete reduction of a reducible nitrogen containing functional group, including conversion of an azo compound, hydroxamic acid compound, hydroxyl amine compound, N-oxide compound, nitro compound, a nitroso compound, a nitrene compound, a nitrite compound, and / or a nitrile compound. In some embodiments, hydrogenation can refer to transfer of one or more reducing equivalents, optionally accompanied by proton transfer, to a compound. Without being bound by theory, hydrogenation may proceed via proton-coupled electron transfer, hydrogen atom transfer, hydride transfer, surface catalysis, and / or other reduction pathways.

[0234] The term “reduction” refers to a chemical or electrochemical process in which a species can gain one or more electrons, decreases in oxidation state, and / or undergoes addition of hydrogen and / or removal of oxygen. Reduction can occur directly at an electrode, via a catalyst, and / or via a redox mediator.

[0235] The term “ hydrogenation rate” refers to the rate at which hydrogen species are added to a compound (or substrate) during a hydrogenation reaction. The hydrogenation rate corresponds to the slope of the product amount vs time plot.

[0236] The term “hydrogen species” refers to an electron / proton pair, a chemisorbed atomic hydrogen (H«), hydride-like species (H“), and / or hydrogen atoms. The term “hydrogen species” may also be referred to herein as “hydrogen”. The term “surface associated hydrogen species” refers to hydrogen species associated with a catalyst surface.

[0237] The term “electron-coupled proton transfer” refers to a hydrogenation pathway in which transfer of one or more electrons is coupled, either sequentially or concertedly, with transfer of one or more protons to a reactant (also referred to as substrate), or reaction intermediate.

[0238] The term “proton-coupled electron transfer” refers to a reaction mechanism in which proton transfer and electron transfer occur in a coordinated manner, including concerted or stepwise pathways, without requiring formation of a discrete hydride intermediate.

[0239] The term “hydride transfer” refers to transfer of a hydrogen atom bearing two electrons (H“) from a donor species, including a metal hydride or surface-bound hydride, to a substrate or reaction intermediate.PATENT

[0240] Attorney Docket No. 51198-070W02

[0241] The term “heterolytic hydrogen activation” refers to cleavage of molecular hydrogen into a proton and a hydride species, typically at a catalytic site, followed by transfer of the proton and hydride to a substrate.

[0242] The term “homolytic hydrogen activation” refers to dissociation of molecular hydrogen into two hydrogen radicals, which may subsequently participate in hydrogenation reactions.

[0243] The term “surface-mediated hydrogenation” refers to hydrogenation reactions proceeding through adsorption of hydrogen species, substrates, or intermediates on a surface, including metallic, catalytic, or electrode surfaces.

[0244] The term “sequential protonation and reduction” refers to hydrogenation pathways in which proton transfer and electron transfer occur in separate steps, in any order, rather than as a concerted event. The term “substrate” refers to a reactant upon which a catalyst, or reagent acts during a chemical reaction. In other words, “substrate” is the species that is transformed into a product through the reaction.

[0245] The term “unsaturated compound” refers to a compound including at least one multiple bond between atoms, including but not limited to a carbon-carbon double bond, carbon-carbon triple bond, a carbonheteroatom (e.g., O, N, or S) multiple bonds, or heteroatom-heteroatom multiple bonds (e.g., multiple bonds between N and N, O, or S). An unsaturated compound may also include a compound with a heteroatom-heteroatom single bond capable of undergoing hydrogenation, e.g., N-OH or N+-O\ In some embodiments, the “unsaturated compound” can include reducible nitrogen containing group such as azo, hydroxamic acid, hydroxyl amine, nitro, nitrene, nitrite, nitrile, nitroso, or N-oxide. In some embodiments, the “unsaturated compound” can include compounds including unsaturation within aromatic or partially aromatic systems that are capable of undergoing hydrogenation. In the context of hydrogenation, an unsaturated compound refers to any compound containing at least one bond capable of undergoing addition of hydrogen or electrons. The term “unsaturated compound” can include any reactant containing a multiple bond (C=C, C=C, C=O, C=S, C=N, N=O, or C=N) species capable of reductive transformation), unless otherwise specified. The group undergoing hydrogenation in an unsaturated compound may be part of or pendant from a linear, branched, monocyclic, multicyclic, or fused cyclic portion of the compound. Cyclic groups may be aryl, heteroaryl, carbocyclic, heterocyclic, or fusions thereof.

[0246] The term “hydrogenated product” refers to the product formed when an unsaturated compound undergoes hydrogenation, such that the degree of unsaturation in the compound is reduced. The hydrogenated product contains a greater number of hydrogen atoms and a lower level of unsaturation relative to the starting material. The term “hydrogenated product” includes, without limitation, products resulting from hydrogenation of carbon-carbon double bonds, carbon-carbon triple bonds, carbonheteroatom multiple bonds (e.g., C=O, C=N), heteroatom-heteroatom bonds, aromatic systems, or any other functional group capable of accepting hydrogen or hydrogen equivalents. In some embodiments, an N-oxide may be deoxygenated, where the oxygen atom is hydrogenated to water,PATENT

[0247] Attorney Docket No. 51198-070W02

[0248] while a hydrogen atom does not bond to the nitrogen atom, e.g., a pyridine N-oxide reduced to a pyridine. Such transformations are contemplated to produce “hydrogenated products,” as used herein. The term “mediator” refers to a compound, other than water, capable of reversibly accepting and donating reducing equivalents in a chemical or electrochemical process, thereby facilitating transfer of reducing equivalents between two species. In some embodiments, a mediator is a redox-active compound that undergoes electrochemical reduction in a cell and subsequently participates in a chemical reaction by transferring reducing equivalents to a substrate, for example, an unsaturated compound and / or a reducible nitrogen containing compound. In some embodiments, the mediator is capable of reversibly incorporating electrons and / or hydrogen atoms during electrochemical reduction and transferring the electrons and / or hydrogen atoms to a substrate during a subsequent chemical reaction. In some embodiments, the mediator is regenerated after transfer of reducing equivalents and is capable of undergoing multiple charging and transfer cycles. In some embodiments, the mediator can be soluble in water. In some embodiments, the mediator can be organic or inorganic, e.g., including a metal atom or ion. An organic mediator is a mediator including a carbon atom, wherein reduction or oxidation involves the making or breaking of a bond to a carbon, nitrogen, oxygen, or sulfur atom. Organic mediators may exclude coordinated or bound metal atoms or metal ions. An inorganic mediator is a mediator that is not an organic mediator, e.g., one in which a metal atom or ion is reduced or oxidized.

[0249] The term “reduced mediator” refers to a mediator that has accepted at least one electron and / or hydrogen atom from another species. The reduced mediator can be partially or fully reduced (or hydrogenated). The partially reduced mediator can incorporate one electron and one proton. The fully reduced mediator can incorporate two electrons and two protons. The reduced mediator can deliver reducing equivalents to a reactant, for example, an unsaturated compound. The reduced mediator can be referred to as the mediator in the reduced state. The reduced mediator is in a lower oxidation state than the mediator in the original state and / or an oxidized mediator.

[0250] The term “oxidized mediator” refers to a mediator in a higher oxidation state relative to the reduced mediator. In some embodiments, a reduced mediator can convert to an oxidized mediator following donation of one or more hydrogen equivalent ( H°, FT, H+, or an electronically coupled proton / electron pair) or electrons. The reduced mediator can be oxidized to the oxidized mediator under suitable conditions. The oxidized mediator can be referred to as the mediator in the oxidized state.

[0251] The term “catalyst” refers to a substance that increases the rate of a chemical reaction and / or facilitates the occurrence of the reaction without being consumed in the overall reaction. The catalyst can participate in intermediate reaction steps and undergo temporary chemical and / or physical changes during the reaction. The catalyst can be supported and / or unsupported, soluble or insoluble, can be regenerated, reused, or continuously present during the reaction. The catalyst can be referred to as “solid phase” throughout the specification. The term “catalyst” is intended to encompass the catalyst in any operative state, including an original state, a hydrogen associated state, and / or intermediate or transient states formed during operation.PATENT

[0252] Attorney Docket No. 51198-070W02

[0253] The term “Janus catalyst” refers to a catalyst structure including at least two distinct regions, surfaces, or domains that differ in chemical composition, physical properties, surface functionality, wettability, catalytic activity, and / or interaction with surrounding phases. In some embodiments, the distinct regions are spatially separated and oriented such that different portion of the catalyst preferentially interact with different phases, reactants, or intermediates. In some embodiments, a Janus catalyst includes a first region configured to interact with an aqueous phase and a second region configured to interact with a nonaqueous phase, thereby enabling catalytic processes at or across a phase boundary. The first region of the Janus catalyst can interact with a mediator in a reduced or oxidized state. The second region of the Janus catalyst can interact with a reactant. In some embodiments, the distinct regions of the Janus catalyst are configured to perform different functions, including but not limited to electron transfer, proton transfer, hydrogen association, adsorption of reactants, or release of products.

[0254] The term “amphipathic” refers to a molecule, material, or catalyst including a hydrophilic portion and a hydrophobic portion, whether inherently present in the structure or introduced through surface modification, functionalization, coating, or attachment of chemical groups.

[0255] The term “amphiphilic” as used herein, refers to a molecule, material, particle, catalyst or region of catalyst including at least one hydrophilic portion and at least one hydrophobic portion, such that the molecule, material, catalyst, or region of catalyst is capable of interacting with both polar and nonpolar environments.

[0256] Ther term “catalyst lattice” refers to the ordered, repeating arrangement of atoms that make up the solid-state structure of a catalyst material. Many catalysts — such as palladium, platinum, nickel, or their alloys and oxides — are crystalline solids in which the constituent atoms occupy specific, periodic positions. This three-dimensional, periodically repeating atomic framework is called the crystal lattice. The lattice includes specific crystallographic planes (e.g., Pd(111), Pd(100)) that determine important catalytic properties such as adsorption strength, reaction pathways, and active-site availability.

[0257] Changes in lattice spacing (e.g., through lattice expansion or contraction) can reflect processes such as hydrogen absorption, formation of hydride phases, oxidation / reduction of the metal, and / or mechanical stress.

[0258] The term “mixture” refers to a physical combination of two or more substances in which each substance retains its individual chemical identity and is not chemically bonded to the others. A mixture may be homogenous, heterogeneous, may exist in one or more phases, and may include solids, liquids, gases, or any combination thereof.

[0259] The term “oxygen evolution reaction” or ‘OER’ refers to an electrochemical reaction in which oxygen is generated through the oxidation of water or hydroxide ions at an electrode. OER typically involves transfer of electrons and protons.

[0260] The term “hydrogen oxidation reaction” or ‘HOR’ refers to an electrochemical reaction in which molecular hydrogen is oxidized at an electrode to produce protons and electrons.PATENT

[0261] Attorney Docket No. 51198-070W02

[0262] The term “recharge” refers to the restoration of a mediator from a spent, reacted, or discharged state to an active redox state capable of participating in a subsequent reaction cycle. Recharge may occur electrochemically, chemically, or by a combination thereof. In some embodiments, recharge can include electrochemical reduction of a mediator following hydrogen transfer to an unsaturated compound.

[0263] The term “posolyte” refers to the positive electrolyte solution in the positive half-cell of an electrochemical cell during spontaneous reaction. In some embodiments, the posolyte can contain one or more active redox species that undergo reduction during spontaneous reaction or oxidation during cell non-spontaneous reaction. In some embodiments, the posolyte can circulate continuously or intermittently through the positive compartment of the electrochemical cell.

[0264] The term “negolyte” refers to the negative electrolyte solution in the negative half-cell of an electrochemical cell during spontaneous reaction. In some embodiments, the negolyte can contain one or more active redox species that undergo oxidation during cell spontaneous reaction or reduction during cell non-spontaneous reaction. The negolyte can circulate through the negative compartment of the electrochemical cell ( or flow cell) under continuous or intermittent flow conditions. The term “standard redox potential” is used to refer to the electrical potential of a half-reaction measured relative to the standard hydrogen electrode (SHE) when all reactants and products are in their standard states. Standard redox potential is the electrode potential of a redox couple measured under standard conditions, including 1 M of all dissolved species and a specified temperature (e.g., room temperature).

[0265] The term “cyclic voltammetry” refers to an electrochemical technique in which a potential applied to a working electrode is varied over time, including in forward and reverse directions, while measuring a resulting current response to characterize electrochemical properties of a material or system. Cyclic voltammogram, the plot resulting from cyclic voltammetry, can be used for determining redox potential, reversibility, and / or number of electrons transferred,

[0266] The term “carbonyl” refers to a C=O functional group, including groups such as aldehyde and ketone groups, as well as carbonyl groups present in carboxylic acids and derivatives.

[0267] The term “Nernstian potential” refers to the electrode potential of a redox molecule under specified non-standard conditions, as determined by the Nernst equation. The Nernstian potential represents the thermodynamic potential established by the ratio of oxidized and reduced species in solution and is calculated according to:

[0268] E = -ln(^)

[0269]

[0270] nF aRed

[0271] where: E is the potential of the redox couple under the actual solution conditions, E° is the standard reduction potential of the couple, R is the gas constant, T is the absolute temperature, n is the number of electrons transferred in the redox process, F is Faraday’s constant, and aOxand aRedare the activities (or effective concentrations) of the oxidized and reduced species, respectively.PATENT

[0272] Attorney Docket No. 51198-070W02

[0273] The term “underpotential deposition threshold” or VuPd refers to the electrode potential at which hydrogen species deposition on the catalysts becomes thermodynamically favorable at potentials more positive than the reversible hydrogen electrode potential. VuPd is typically determined experimentally by cyclic voltammetry and corresponds to the onset potential at which a measurable hydrogen-adsorption feature first appears in the voltammogram under the specified electrolyte, temperature, and catalyst conditions.

[0274] The term “aldehyde” refers to a compound or group comprising a terminal carbonyl group in which the carbonyl carbon is bonded to a hydrogen atom. In other words, an “aldehyde” is a -CHO functional group or compound including such a group.

[0275] The term “reducible nitrogen containing compound” refers to a compound including at least one nitrogen atom bonded to a carbon atom, including a multiple bond. Reducible nitrogen containing compound can include azo, hydroxamic acid, hydroxyl amine, nitro, nitrene, nitrite, nitrile, nitroso, or N-oxide, or a derivative thereof.

[0276] The term “nitrite” refers to a nitrite anion NO2“ species or a nitrite ester (R-O-N=O).

[0277] The term “nitrene” denotes a monovalent nitrogen atom with two nonbonded electrons (R-N:).

[0278] The term “alkene” refers to an unsaturated hydrocarbon containing at least one carbon-carbon double bond (C=C).

[0279] The term “alkyne” refers to an unsaturated hydrocarbon containing at least one carbon-carbon triple bond (C=C).

[0280] The term “aliphatic” refers to a straight, branched, or non-aromatic cyclic carbon-containing compound.

[0281] The term “alkyl” refers to straight chain or branched saturated groups. Alkyl groups are exemplified by methyl, ethyl, n- and iso-propyl, n-, sec-, iso- and tert-butyl, neopentyl, and the like, and may be optionally substituted with one or more substituents. An “alkane” is the molecular equivalent of the “alkyl group.”

[0282] The term “alkylene” refers to a divalent straight chain or branched saturated groups and may be optionally substituted with one or more substituents.

[0283] The term “alkenyl” refers to straight chain or branched unsaturated groups having at least one carboncarbon double bond. Alkenyl groups are exemplified by ethenyl, propenyl, butenyl, and the like, and may be optionally substituted with one or more substituents.

[0284] The term “alkynyl” refers to straight chain or branched unsaturated groups having at least one carboncarbon triple bond. Alkynyl groups are exemplified by ethynyl, propynyl, butynyl, and the like, and may be optionally substituted with one or more substituents.

[0285] The term “alkoxy” refers to a group of formula -OR, wherein R is an alkyl group.

[0286] The term “alkyl thio” refers to -S-R, where R is an alkyl group.PATENT

[0287] Attorney Docket No. 51198-070W02

[0288] The term “alkyl ester” refers to -COOR, where R is an alkyl group.

[0289] The term “amino” or “amine” refers to -NH2 or -NR2, wherein each R is, independently, H, alkyl, alkenyl, alkynyl, aryl, carbocyclyl, heteroaryl, or heterocyclyl.

[0290] The term “amide” refers to -C(O)NR2 or -NRC(O)R, wherein each R is, independently, H, alkyl, alkenyl, alkynyl, aryl, carbocyclyl, heteroaryl, or heterocyclyl.

[0291] The term “ammonium” refers to -NR3+’ wherein each R is, independently, H, alkyl, alkenyl, alkynyl, aryl, carbocyclyl, heteroaryl, or heterocyclyl.

[0292] The term “aromatic” refers to aryl or heteroaryl.

[0293] The term “aryl” refers to an aromatic cyclic group in which the ring atoms are all carbon. Aryl groups may be monocyclic or multicyclic and may include a fused carbocyclyl group. Exemplary aryl groups include phenyl, naphthyl, and anthracenyl. Aryl groups may be optionally substituted with one or more substituents.

[0294] The term “azo” refers to -N=N-.

[0295] The term “azoxy” refers to -N=N(O).

[0296] The term “carbocyclyl” refers to a non-aromatic cyclic group in which the ring atoms are all carbon. Carbocyclyl groups may be monocyclic or polycyclic. Exemplary carbocyclyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Carbocyclyl groups may be optionally substituted with one or more substituents.

[0297] The term “carboxyl” refers to -COOH.

[0298] The term “catalyst mass” or “catalyst load” refers to the total amount of catalyzing substance present at the start of a chemical reaction.

[0299] The term “halo” refers to fluoro, chloro, bromo, or iodo.

[0300] The term “heteroaryl” refers to an aromatic cyclic group in which the ring atoms include at least one carbon and at least one O, N, or S atom, provided that at least three ring atoms are present.

[0301] Heteroaryl groups may be monocylic or polycyclic and may include a fused aryl, carbocyclyl, or heterocyclyl group. Each ring may include 1 to 6 carbons and 1 to 4 heteratoms selected from O, N, and S. Exemplary heteroaryl groups include oxazolyl, isoxazolyl, tetrazolyl, pyridyl, thienyl, furyl, pyrrolyl, imidazolyl, pyrimidinyl, thiazolyl, indolyl, quinolinyl, isoquinolinyl, benzofuryl, benzothienyl, pyrazolyl, pyrazinyl, pyridazinyl, isothiazolyl, benzimidazolyl, benzothiazolyl, benzoxazolyl, oxadiazolyl, thiadiazolyl, and triazolyl. Heteroaryl groups may be optionally substituted with one or more substituents.

[0302] The term “heterocyclyl” refers to a non-aromatic cyclic group in which the ring atoms include at least one carbon and at least one O, N, or S atom, provided that at least three ring atoms are present. Heterocyclyl groups may be monocylic or polycyclic and may include a fused carbocyclyl or heterocyclyl group. Each ring may include 1 to 6 carbons and 1 to 4 heteratoms selected from O, N, and S. Exemplary heterocyclyl groups include epoxide, thiiranyl, aziridinyl, azetidinyl, thietanyl,PATENT

[0303] Attorney Docket No. 51198-070W02

[0304] dioxetanyl, morpholinyl, thiomorpholinyl, piperazinyl, piperidinyl, pyrrolidinyl, tetrahydropyranyl, tetrahydrofuranyl, dihydrofuranyl, tetrahydrothienyl, dihydrothienyl, dihydroindolyl, tetrahydroquinolyl, tetrahydroisoquinolyl, pyranyl, pyrazolinyl, pyrazolidinyl, dihydropyranyl, tetrahydroquinolyl, imidazolinyl, imidazolidinyl, pyrrolinyl, oxazolidinyl, isoxazolidinyl, thiazolidinyl, isothiazolidinyl, dithiazolyl, and 1 ,3-dioxanyl. Heterocyclyl groups may be optionally substituted with one or more substituents.

[0305] By “hydroxamic acid” is meant -C(O)NHOH.

[0306] By “hydroxyl” is meant -OH.

[0307] By “hydroxyl amine” is meant -NHOH.

[0308] The term “fluidically coupled” refers to any connection between at least two system elements that allows for fluid flow therebetween.

[0309] The term “nitro” refers to a functional group or compound including a nitrogen atom bonded to two oxygen atoms (-NO2).

[0310] The term “nitroso” refers to a -N=O group, or a compound in which a nitrogen atom is double-bonded to an oxygen atom and bonded to a carbon or hydrogen atom.

[0311] The term “nitrile” refers to a functional group or compound containing a carbon atom triple-bonded to a nitrogen atom (-C=N).

[0312] The term “oxo” refers to a functional group containing an oxygen atom double-bonded to another atom (e.g., =0).

[0313] The term “phosphonyl” refers to -PO3R2, where each R is H or alkyl, provided at least one R is alkyl, as defined herein. An exemplary ion of phosphoryl is -PO3R-.

[0314] The term “phosphoryl” refers to a phosphorous atom double-bonded to an oxygen atom (P=0) and bonded to zero or more substituents, including organic or inorganic groups.

[0315] The term “sulfide” refers to -S-.

[0316] The term “sulfonyl” refers to -SO2R, where R is alkyl, alkenyl, alkynyl, aryl, carbocyclyl, heteroaryl, or heterocyclyl.

[0317] The term “sulfonate” refers to -SO3H.

[0318] The term “thiol” refers to -SH.

[0319] Substituents may be optionally substituted with halo, optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; oxo, -ON; -NO2; -0Ra; -N(Ra)2-3; -C(=O)Ra; -C(=O)ORa; -S(=0)2Ra; -S(=O)2ORa; -P(=O)Ra2; -O-P(=O)(ORa)2, or -P(=O)(ORa)2, or an ion thereof; wherein each Rais, independently, H, optionally substituted C1-6 alkyl; optionally substituted C2-6 alkenyl; optionally substituted C2-6 alkynyl; optionally substituted C3-10 carbocyclyl; optionallyPATENT

[0320] Attorney Docket No. 51198-070W02

[0321] substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S. Cyclic substituents may also be substituted with optionally substituted C1-6 alkyl, optionally substituted C2-6 alkenyl, or optionally substituted C2-6 alkynyl. In specific embodiments, substituents may be optionally substituted with halo, optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; oxo, -NO2; -ORa; -N(Ra)2-3; -C(=O)Ra; -C(=O)ORa; -S(=O)2Ra; -S(=O)2ORa; -P(=O)Ra2; -O-P(=O)(ORa)2, or -P(=O)(ORa)2, or an ion thereof; wherein each Rais, independently, H, optionally substituted C1-6 alkyl; optionally substituted C2-6 alkenyl; optionally substituted C2-6 alkynyl, optionally substituted C3-10 carbocyclyl; optionally substituted C1-9 heterocyclyl having one to four heteroatoms independently selected from O, N, and S; optionally substituted C6-20 aryl; optionally substituted C1-9 heteroaryl having one to four heteroatoms independently selected from O, N, and S; and cyclic substituents may also be substituted with C1-6 alkyl. In specific embodiments, alkyl groups may be optionally substituted with one, two, three, or, in the case of alkyl groups of two carbons or more, four substituents independently selected from the group consisting of halo, hydroxyl, C1-6 alkoxy, SO3H, amino, nitro, carboxyl, phosphoryl, phosphonyl, thiol, C1-6 alkyl ester, optionally substituted C1-6 alkyl thio, and oxo, or an ion thereof.

[0322] FIG. 1 is a block diagram of a system 1000 for production of hydrogenated products from unsaturated compounds, according to an embodiment. In some embodiments, the system 1000 can include a first module, for example, a reactor 1100. In some embodiments, the reactor 1100 can provide a physical location, for example, a chamber, a tank, etc., where hydrogenation takes place. In some embodiments, the reactor 1100 can be configured to bring a solid phase 1500 including a catalyst, an aqueous phase 1600 including a reduced mediator (or a mediator in a reduced state), and a nonaqueous phase 1400 including a reactant (e.g., an unsaturated compound) into contact. Since the solid phase includes the catalyst, both terms can be used interchangeably, except where apparent from context, and a single reference number may be used to denote either the catalyst or the solid phase throughout the specification.

[0323] In some embodiments, the reactor 1100 can facilitate interaction among the solid phase 1500, the aqueous phase 1600, and the nonaqueous phase 1400. In some embodiments, the reactor 1100 can facilitate hydrogenation of the reactant in the nonaqueous phase 1400. In some embodiments, the hydrogenation of the reactant can be facilitated by the catalyst and the reduced mediator.

[0324] In some embodiments, the reactant 1100 can include an unsaturated compound. In some embodiments, the unsaturated compound can include at least one of an alkene, an alkyne, a carbonyl (e.g., a ketone, and / or an aldehyde), a reducible nitrogen (e.g., azo, hydroxamic acid, hydroxyl amine, N-oxide a nitrite, a nitro, a nitroso, a nitrene, and / or a nitrile). In some embodiments, the reactant can receive reducing equivalents to form a hydrogenated product. In some embodiments, the reactant (e.g., unsaturated compound) can receive reducing equivalents from the aqueous phase, e.g., reduced mediator and / or water, via the catalyst.PATENT

[0325] Attorney Docket No. 51198-070W02

[0326] In some embodiments, the mediator is configured to reversibly accept and / or donate reducing equivalents in a chemical or electrochemical process, thereby facilitating transfer of reducing equivalents between two species. In some embodiments, the mediator can undergo electrochemical reduction or oxidation in an electrochemical cell and subsequently participate in a chemical reaction by transferring reducing equivalents to a compound, for example, an unsaturated compound and / or a reducible nitrogen containing compound. In some embodiments, the mediator is capable of reversibly incorporating electrons and / or hydrogen atoms during electrochemical reduction and transferring the electrons and / or hydrogen atoms to a substrate during a subsequent chemical reaction. In some embodiments, the mediator in the reduced state can carry reducing equivalents. In some embodiments, the mediator in the reduced state can transfer reducing equivalents to the reactant, e.g., via the catalyst.

[0327] In some embodiments, the catalyst can facilitate hydrogenation of the reactant 1100. In some embodiments, the catalyst can promote transfer of hydrogen species from the aqueous phase to the reactant. In some embodiments, the catalyst can form a catalytic intermediate capable of delivering hydride, hydrogen atom, or proton-coupled electron equivalents to an unsaturated bond of the reactant. In some embodiments, the catalyst can facilitate hydrogenation of the reactant via metal-hydride formation, hydrogen atom transfer, proton-coupled electron transfer, and / or surface catalysis. Without wishing to be bound by any particular theory, the catalyst can lower an energy barrier of hydrogenation by stabilizing the reduced mediator (e.g., hydrogen carrier) and activating the IT bond of the reactant. In some instances, the reduced mediator can transfer hydrogen species without the catalyst, the rate of transfer may be significantly slower or less selective.

[0328] In some embodiments, the catalyst can include one or more metals, metal oxides, metal sulfides, supported catalysts, porous catalysts, surface-modified catalysts, or combinations thereof. Suitable metals can include but are not limited to palladium (Pd), platinum (Pt), nickel (Ni), cobalt (Co), iron (Fe), rhenium (Re), rhodium (Rh), ruthenium (Ru), iridium (Ir), manganese (Mn), molybdenum (Mo), and copper (Cu). In some embodiments, the catalyst can include a porous metal catalyst such as Raney nickel or Raney copper. Examples of catalysts include Lindlar catalyst, Wilkinson’s catalyst, Crabtree’s catalyst, Shvo catalyst, Pearlman’s catalyst, PtOz, nickel boride, NiO, cobalt boride, copper chromite, hydridotetrakis(triphenylphosphine)rhodium(l), ReOs, RezO?, Nishimura’s catalyst, Kndlker complex, Urushibara nickel, and M0S2. Metal catalysts may also be bound to one or more ligands as is known in the art. Any combination or alloy of the foregoing can also be used.

[0329] In some embodiments, the reactor 1100 can include an interfacial region between an aqueous phase 1600, and a nonaqueous phase 1400 wherein reactants are transformed (e.g., hydrogenated). In some embodiments, the reactor 1100 can provide an interface between the aqueous phase 1600, and solid phase 1500. In some embodiments, the reactor 1100 can provide an interface between the nonaqueous phase 1400 and the solid phase 1500. In some embodiments, the interfacial region can include a physical interface, for example, a mesh, web, or porous layer where the solid phase 1500 may reside and form an interface between the nonaqueous phase 1400 and the aqueous phase 1600.PATENT

[0330] Attorney Docket No. 51198-070W02

[0331] In some embodiments, the reactor 1100 can include a suspension including a mixture of the solid phase 1500, the aqueous phase 1600, and the nonaqueous phase 1400. In some embodiments, the interfaces between different phases can be formed via agitation of the solid phase 1500, the aqueous phase 1600, and the nonaqueous phase 1400. For example, the solid phase 1500, the aqueous phase 1600, and the nonaqueous phase 1400 may have different miscibility or density, causing them to suspended as interfacial layers (e.g., aqueous phase 1600 and nonaqueous phase 1400 with the solid phase 1500 disposed therebetween) within the reactor 1100.

[0332] In some embodiments, agitation can be provided via stirring, shaking, convection, recirculation, sparging, mechanical mixing, or any combination thereof. In some embodiments, agitation can include vigorous stirring or induced convection to ensure sufficient mixing and promote repeated or continuous contact of the solid phase 1500, the aqueous phase 1600, and the nonaqueous phase 1400. The level of agitation can be adjusted to maintain the catalyst in suspension, to enhance mass transfer, and / or to maintain a stable emulsion or dispersion.

[0333] In some embodiments, the reactor 1100 can include a fixed-bed system. In some embodiments, the aqueous phase-solid phase interface, and the nonaqueous phase-solid phase interface can be established using a fixed bed system, in which the solid phase 1500 can be immobilized within a portion of the reactor 1100. In some embodiments, the aqueous phase 1600 and the nonaqueous phase 1400 can flow through or across the packed bed in a co-current, counter-current, and / or alternate manner. In some embodiments, reactor parameters such as flow rate, residence time, pressure drop, phase distribution, and wetting characteristics can be selected to achieve adequate contact of the phases.

[0334] In some embodiments, in both suspension system and fixed bed system, the reactor 1100 can further include temperature-control elements, baffling, internal supports, or flow-directing structures to optimize the contact between phases and to maintain the desired reaction environment. The reactor is not limited to any particular reactor geometry, scale, or flow regime and any suitable geometry, scale, or flow regime reactor may be used.

[0335] In some embodiments, the system 1000 can optionally include a second module. In some embodiments, the mediator in an aqueous phase can be reduced to form the reduced mediator in the second module. In some embodiments, the mediator is configured to undergo reduction under suitable reaction conditions. In some embodiments, the mediator can be reduced in an electrochemical process. The reduction of the mediator is not limited to the electrochemical process and may occur via chemical, catalytic, photochemical, thermal, or other redox mechanisms.

[0336] In some embodiments, the mediator can be reduced in an electrochemical cell 1200. The electrochemical cell 1200 can be configured such that the mediator can receive at least one reducing equivalent (or electron and / or hydrogen) from another species. The electrochemical cell 1200 is described in further detail with reference to FIG. 2.

[0337] In some embodiments, the reactor 1100 and the electrochemical cell 1200 can be fluidically coupled such that the aqueous phase 1600 including the mediator can be transferred between thePATENT

[0338] Attorney Docket No. 51198-070W02

[0339] electrochemical cell 1200 and the reactor 1100. In some embodiments, the electrochemical cell 1200, and the reactor 1100 can operate in a continuous or semi-continuous manner. In some embodiments, at least a portion of the aqueous phase 1600 can be transferred from the electrochemical cell 1200 to the reactor 1100 to provide a reduced mediator into the reactor 1100 for hydrogenation of the reactant dissolved in the nonaqueous phase 1400. Transfer of the mediator between the reactor 1100 and the electrochemical cell 1200 can occur continuously, periodically, or intermittently. Transfer of the mediator between the reactor 1100 and the electrochemical cell 1200 can occur via diffusion, convection, or flow.

[0340] In some embodiments, contact of the aqueous phase 1600 including the reduced mediator, the nonaqueous phase 1400 including the reactant, and the solid phase 1500 including the catalyst in the reactor 1100 can form a hydrogenated product and a mediator in an oxidized state (i.e. , an oxidized mediator).

[0341] In some embodiments, the system 1000 can further include a separator 1300. The separator 1300 will be described in further detail with reference to FIG. 2. In some embodiments, the separator 1300 can be fluidically coupled to the reactor 1100 and configured to operate in a continuous or semi-continuous manner.

[0342] In some embodiments, the aqueous phase 1600, the nonaqueous phase 1400, and the solid phase 1500 can be separated from each other in the separator 1300. In some embodiments, at least a portion of the aqueous phase 1600 including the oxidized mediator, can be recirculated into the electrochemical cell 1200 for regeneration and subsequent hydrogenation processes. In some embodiments, the solid phase 1500 can be recirculated into the reactor 1100 for subsequent hydrogenation processes. In some embodiments, the nonaqueous phase 1400 can be recirculated into the reactor 1100 for further hydrogenation. Embodiments described herein can enable reduction of the mediator and hydrogenation of the reactant in separate modules, and enhance control over reaction conditions, improve the hydrogenation efficiency, reduce waste, and / or enhance selectivity. FIG. 2 is a diagram of a system 2000 for continuous production of a hydrogenated product 2700, according to an embodiment. In some embodiments, system 2000 for continuous production of a hydrogenated product 2700 can include an electrochemical cell 2200. In some embodiments, the electrochemical cell 2200 can be a single cell, stacked cells, flow cell, membrane electrode assembly, or any other suitable structure for electrochemical reduction of the mediator 2610.

[0343] In some embodiments, the electrochemical cell 2200 can include at least an electrode including, for example, a carbon-based material, such as graphite, to facilitate reversible redox reactions of the mediator 2610. In some embodiments, the electrochemical cell 2200 can be configured as a flow cell including a positive electrolyte (posolyte) 2204 compartment and a negative electrolyte (negolyte) 2202 compartment. In some embodiments, the electrochemical cell 2200 can further include a positive electrode 2203 in contact with the posolyte 2204 and a negative electrode 2201 in contact with the negolyte 2202. In some embodiments, each of the posolyte 2204 and the negolyte 2202 can be configured to flow through a respective compartment during operation, for example, using one or more pumps or circulation loops.PATENT

[0344] Attorney Docket No. 51198-070W02

[0345] In some embodiments, the flow configuration in the electrochemical cell 2200 can include up-flow, down-flow, serpentine-flow, or other suitable channel geometries configured to promote uniform distribution, reduce concentration gradients and improve mass transport efficiency. In some embodiments, the up-flow refers to a flow configuration where the electrolyte enters an inlet at a bottom portion of the compartment and flows upward toward an outlet at a top portion of the compartment. In some embodiments, the down-flow refers to a flow configuration where the electrolyte enters an inlet at the top portion of the compartment and flows downward toward an outlet at the bottom portion of the compartment. In some embodiments, the serpentine-flow refers to a flow configuration where one or both of the electrolytes include serpentine flow channels patterned into a flow plate.

[0346] In some embodiments, the posolyte 2204 and / or the negolyte 2202 can include a mediator 2610 configured to undergo electrochemical reduction within the flow cell 2200 to form a reduced mediator 2620. In some embodiments, the reduced mediator 2620 can include one or more reducing equivalents (e.g., electrons and protons). In some embodiments, the reduced mediator 2620 can be dissolved in an aqueous phase (or solution). In some embodiments, the mediator can include any of the mediators previously described herein.

[0347] It will be understood by one skilled in the art that the mediator may alternatively be reduced in negolyte if the counter redox active species has a higher redox potential.

[0348] In some embodiments, posolyte and negolyte can include an electrolyte salt. In some embodiments, the electrolyte salt can include KOI. In some embodiments, the electrolyte salt can include an alkali metal halide, sulfate, and / or nitrate. In some embodiments, the electrolyte salt can include NaCI, LiCI, KBr, NaBr, LiBr, K2SO4, NazSC , IJ2SO4, KNO3, NaNOs, and / or any combination thereof. Other suitable electrolyte salts are known in the art.

[0349] In some embodiments, the concentration of the electrolyte salt in the negolyte and / or the posolyte can be from about 0.5 M to about 1.5 M, inclusive of all values and ranges in between. In some embodiments, the concentration of the electrolyte salt in the negolyte and / or the posolyte can be at least about 0.5 M, at least about 0.6 M, at least about 0.7 M, at least about 0.8 M, at least about 0.9 M, at least about 1 M, at least about 1.2 M, at least about 1.3 M, at least about 1.4 M, or at least about 1.5 M, inclusive of all values and ranges in between. In some embodiments, the concentration of the electrolyte salt in the negolyte and / or the posolyte can be no more than about 1.5 M, no more than about 1.4 M, no more than about 1.3 M, no more than about 1.2 M, no more than about 1.1 M, no more than about 1 M, no more than about 0.9 M, no more than about 0.8 M, no more than about 0.7 M, no more than about 0.6 M, or no more than about 0.5 M, inclusive of all values and ranges in between. Combinations of the above-referenced concentrations of the electrolyte salt in the negolyte and / or the posolyte are also possible (e.g., at least about 0.5 M, and no more than about 1.5 M, or at least about 0.2 M and no more than about 0.5 M), inclusive of all values and ranges therebetween. In some embodiments, the concentration of the electrolyte salt in the negolyte and / or the posolyte can be about 0.5 M, about 0.6 M, about 0.7 M, about 0.8 M, about 0.9 M, about 1 M, about 1.1 M, about 1.2 M, about 1.3 M, about 1 .4 M, or about 1.5 M, inclusive of all values and ranges therebetween.PATENT

[0350] Attorney Docket No. 51198-070W02

[0351] In some embodiments, the electrode (e.g., positive electrode 2203 or negative electrode 2201) material can include nickel, carbon felt, stainless mesh, and / or porous carbon. In some embodiments, the posolyte 2204 can have a pH of at least about 11 (e.g., at least about 11 , about 12, about 13, or about 14). In some embodiments, the posolyte 2204 (e.g., an aqueous solution) can include alkaline species such as KOH, NaOH, or LiOH in a concentration of from about 1 M to about 10 M (e.g., from about 1 M to about 10 M, about 2 M to about 10 M, about 3 M to about 10 M, about 4 M to about 10 M, about 5 M to about 10 M, about 6 M to about 10 M, about 7 M to about 10 M, about 8 M to about 10 M, about 9 M to about 10 M, about 2 M to about 9 M, about 3 M to about 8 M, about 4 M to about 7 M, or about 5 M to about 6 M), inclusive of all values and ranges, therebetween. In some embodiments, the concentration of alkaline species in the posolyte 2204 can be at least about 1 M, at least about 2 M, at least about 3 M, at least about 4 M, at least about 5 M, at least about 6 M, at least about 7 M, at least about 8 M, at least about 9 M, or at least about 10 M, inclusive of all values and ranges in between. In some embodiments, the concentration of alkaline species in the posolyte 2204 can be no more than about 10 M, no more than about 9 M, no more than about 8 M, no more than about 7 M, no more than about 6 M, no more than about 5 M, no more than about 4 M, no more than about 3 M, no more than about 2 M, or no more than about 1 M, inclusive of all values and ranges in between. Combinations of the above-referenced concentrations are also possible (e.g., at least about 1 M, and no more than about 10 M, or at least about 5 M and no more than about 6 M), inclusive of all values and ranges therebetween. In some embodiments, the concentration of alkaline species in the posolyte 2204 can be about 1 M, about 2 M, about 3 M, about 4 M, about 5 M, about 6 M, about 7 M, about 8 M, about 9 M, or about 10 M, inclusive of all values and ranges in between. In some embodiments, the posolyte 2204 can include buffers, stabilizers, and / or conductivity enhancers. In some embodiments, an inlet can be fluidically coupled to introduce a mediator 2610 containing posolyte 2204 into the electrochemical flow cell 2200. In some embodiments, an outlet can be fluidically coupled to the electrochemical flow cell 2200 to transfer the posolyte including the reduced mediator (or mediator in the reduced state) 2620 into the reactor 2100. In some embodiments, the flow cell 2200 can be electrically coupled to a power source 2208 configured to apply a voltage or current across the flow cell, thereby providing an electrical potential between the positive electrode 2203 and the negative electrode 2201 of the flow cell 2200.

[0352] In some embodiments, the flow cell 2200 can further include a membrane 2206 disposed between the posolyte 2204 and the negolyte 2202. In some embodiments, the membrane 2206 can be ion conductive (e.g., anion-exchange membrane (AEM) e.g., proton-exchange membrane (PEM)). In some embodiments, the membrane 2206 can be a size exclusion membrane or a semi-permeable membrane. In some embodiments, the membrane 2206 can separate the positive electrode 2203 from the negative electrode 2201 to prevent the crossover of electroactive species, thereby reducing parasitic re-oxidation of the reduced mediator 2620. In some embodiments, the membrane 2206 can include a porous or semi-porous material having a molecular weight cutoff or pore size selected to inhibit mediator transport while allowing ion conductivity. In some embodiments, the membrane 2206 allows the transport of protons generated in the posolyte 2204 to the negolyte 2202.PATENT

[0353] Attorney Docket No. 51198-070W02

[0354] In some embodiments, following reaction can occur on the anode (e.g., negative electrode 2201) side of the electrochemical cell 2200 (e.g., at the interface between the negative electrode 2201 and the negolyte 2202 and / or in the negolyte 2202 surrounding the negative electrode 2201):

[0355] H2O-2e —> 0.5 O2+ 2 H+(1).

[0356] In some embodiments, following reaction can occur on the cathode (e.g., positive electrode 2203) side of the electrochemical cell 2200 (e.g., at the interface between the positive electrode 2203 and the posolyte 2204 and / or in the posolyte 2204 surrounding the positive electrode 2203):

[0357] Q+ 2e + 2 H+^ H2Q (2),

[0358] where Q is an oxidized mediator.

[0359] Therefore, the net reaction in the electrochemical cell 2200 can include:

[0360] H2O + Q ^ 0.5 O2+ H2Q (3).

[0361] In some embodiment, the reaction occurring at the solid phase contact with the aqueous phase can include:

[0362] H2Q ^ Q + 2 H‘(4),

[0363] wherein H* refers to surface associated hydrogen species on the catalyst (e.g., solid phase).

[0364] In some embodiments, when the solid phase contacts the nonaqueous phase, the following reaction occurs:

[0365] 2 H‘+ R^ H2R (5),

[0366] where R is the reactant.

[0367] In some embodiments, reaction (5) can occur at the interface of the solid phase and the nonaqueous phase. In some embodiments, reaction (5) can occur in the nonaqueous phase.

[0368] In some embodiments, the system 2000 can further include a reactor 2100. In some embodiments, the reactor 2100 may include one or more inlets. The reactor 2100 can be substantially similar to the reactor 1100, and unless otherwise indicated, the description of reactor 1100 applies to the reactor 2100. Therefore, certain features and details of the reactor 2100 are not described in detail herein. In some embodiments, a solid phase including the catalyst feed 2510 can be introduced to the reactor 2100 by the one or more inlets. In some embodiments, an aqueous phase including the reduced mediator 2620 can be introduced to the reactor 2100, e.g., by the one or more inlets. In some embodiments, at least a portion of the aqueous phase can be introduced from the electrochemical cell 2200 to the reactor 2100. In some embodiments, a nonaqueous phase including a reactant 2410 can be introduced to the reactor 2100, e.g., by the one or more inlets.

[0369] In some embodiments, the reactor 2100 is configured to bring the solid phase, the aqueous phase, and the nonaqueous phase, into contact, thereby providing an interface between the aqueous phase and the solid phase, the aqueous phase and the nonaqueous phase, and the nonaqueous phase and the solid phase.PATENT

[0370] Attorney Docket No. 51198-070W02

[0371] In some embodiments, the hydrogenation process is performed in a fixed-bed system (not shown), in which the solid phase including the catalyst is immobilized within the reactor 2100. The catalyst immobilized within the reactor can be referred to as fixed catalyst. In some embodiments, a liquid phase, including the aqueous phase and / or the nonaqueous phase can be supplied to the fixed-bed reactor 2100. In some embodiments, the aqueous phase and the nonaqueous phase can be introduced to the fixed-bed reactor 2100 as separate phases or as a premixed biphasic system, or sequentially. As the liquid stream passes over the fixed catalyst, contact between the liquid phase and the solid phases can occur, enabling the hydrogenation reaction to proceed between the reduced mediator 2620 and the reactant 2410 (e.g., the unsaturated compound).

[0372] In some embodiments, the hydrogenation process is performed in a suspension system. In some embodiments, the solid phase including the catalyst 2510, the aqueous phase including the reduced mediator 2620, and the nonaqueous phase including the reactant 2410 can be introduced into the suspension system, wherein agitation can promote contact among the aqueous phase, the nonaqueous phase, and the solid phase, thereby enabling the hydrogenation process to proceed. In some embodiments, agitator 2104 can be configured to agitate a mixture including the solid phase, the aqueous phase, and the nonaqueous phase, thereby enhancing an interfacial area between the aqueous phase and the solid phase, as well as the nonaqueous phase and the solid phase. In some embodiments, the agitator 2104 can include an agitation power source. In some embodiments, agitation can be provided via stirring, shaking, convection, recirculation, sparging, mechanical mixing, sonication, vibration, or any combination thereof. In some embodiments, the agitator 2104 can include vigorous stirring or induced convection to ensure sufficient mixing and promote repeated or continuous contact of the solid phase, the aqueous phase, and the nonaqueous phase. The level of agitation can be adjusted to maintain the catalyst feed 2510 in suspension, to enhance mass transfer, and / or to maintain a stable emulsion or dispersion.

[0373] In some embodiments, the system 2000 can further include a module for separation of the solid phase, the aqueous phase, and the nonaqueous phase. In some embodiments, the separation of the solid phase, the aqueous phase, and the nonaqueous phase can occur in a single step in one separator. In some embodiments, the separation process can occur in the reactor 2100, during or after the hydrogenation process. In some embodiments, the separation can occur in a single step. In some embodiments, the separation can occur in a multi-step (e.g., two-step, three-step, or four-step) process. In some embodiments, the system 2000 can include a first separator 2310 and a second separator 2320.

[0374] For example, a first mixture 2120 including the solid phase, the aqueous phase, and the nonaqueous phase can be introduced to the first separator 2310. In some embodiments, the solid phase can be removed in the first separator 2310 via filtration (e.g., gravity filtration, vacuum filtration, pressure filtration, cross-flow or tangential-flow filtration, depth filtration, membrane filtration), settling (e.g., via a flocculant, a coagulant, a baffle design, a settling tank), centrifugation (e.g., bath centrifuge, continuous decanter centrifuge, disk-stack centrifuge), magnetic separation (e.g., via magnetic nanoparticles or magnetic support), or any other suitable method. In some embodiments, removal ofPATENT

[0375] Attorney Docket No. 51198-070W02

[0376] the solid phase from the first mixture 2120 can form a second mixture 2130 including the aqueous phase and the nonaqueous phase.

[0377] In some embodiments, the separated solid phase including the separated catalyst 2520 can be recycled to the reactor 2100 for continued hydrogenation process. In some embodiments, the separated catalyst 2520 can be substantially similar to the catalyst feed 2510 initially introduced into the reactor 2100. In some embodiments, the catalyst feed 2510 can lose some catalytic properties, for example, activity, selectivity and / or structural integrity, during the hydrogenation process. In some embodiments, the separated catalyst 2520 can be processed further before being recycled into the reactor 2100. In some embodiments, the separated catalyst 2520 can undergo additional processes such as washing, reconditioning, re-impregnation, regeneration prior to recycling into the reactor 2100.

[0378] In some embodiments, the first separator 2310 can include a pair of angled internal baffles 2306 to direct the liquid phase (also referred to as the second mixture 2130 toward an outlet to be communicated to the second separator 2320. In some embodiments, the liquid phase includes the aqueous phase and the nonaqueous phase. After removal of the solid phase, the second mixture 2130 can be transferred from the first separator 2310 to the second separator 2320.

[0379] In some embodiments, the separation of the aqueous phase from the nonaqueous phase can occur in the second separator 2320 via decanting, centrifugation, gravity settlement, or any other suitable liquid-liquid separation techniques. In some embodiments, the separated nonaqueous phase can include the hydrogenated product 2700. In some embodiments, the hydrogenated product 2700 can include impurities, for example, the reactant 2410. In some embodiments, the hydrogenated product 2700 can be further processed for purification. In some embodiments, the separated aqueous phase including the oxidized mediator 2630 can be recycled to the electrochemical cell 2200 to form the reduced mediator 2620 for continuation of hydrogenation process. In some embodiments, the oxidized mediator 2630 and the mediator 2610 may be essentially the same.

[0380] In some embodiments, the second separator can include coalescence plates. In some embodiments, coalescence plates can facilitate separation of combined liquids into two phases, including the aqueous phase and nonaqueous phase. In some embodiments, the aqueous phase and the nonaqueous phase can be referred to as recovered aqueous phase and recovered nonaqueous phase. In some embodiments, the aqueous phase can also include an amount of the nonaqueous solution (or medium). In some embodiments, the nonaqueous phase can include an amount of the aqueous solution (or medium).

[0381] In some embodiments, the cross-sectional area of the second separator can affect the purity of the aqueous phase and the nonaqueous phase. The combined liquids may include a dispersion of droplets of nonaqueous phase and aqueous phase. Along the width Wi of the separation section, droplets of the aqueous phase coalesce to eventually form the aqueous phase and droplets of the nonaqueous phase coalesce to eventually form the nonaqueous phase. A larger cross-sectional area can increase the residence time, allowing droplets to rise or settle under gravity, and coalesce to eventually form the aqueous phase and the nonaqueous phase.PATENT

[0382] Attorney Docket No. 51198-070W02

[0383] In some embodiments, the second separator can further include an aqueous phase outlet. In some embodiments, the second separator can include a plurality of aqueous phase outlets. In some embodiments, the aqueous phase containing the oxidized organic mediator can be removed from the aqueous phase outlet. In some embodiments, the second separator can further include a nonaqueous phase outlet. In some embodiments, the second separator can include a plurality of nonaqueous phase outlets. In some embodiments, the partially or fully reduced products can be removed from the nonaqueous phase outlet. In some embodiments, the nonaqueous phase outlet or aqueous phase outlet can be disposed at a height, adjusted based on the relative volume and densities of the aqueous phase and nonaqueous phase.

[0384] In some embodiments, the second separator can further include a baffle. In some embodiments, the baffle can control the fluid flow. In some embodiments, the baffle can be configured to inhibit vortex formation, make the flow patterns more uniform, and / or increase the residence time. In some embodiments, the baffle can promote phase separation and help droplet coalesce. In some embodiments, the baffle can guide the flow toward outlets.

[0385] In some embodiments, the second separator can further include an aqueous phase weir. In some embodiments, the aqueous phase weir can act as a barrier proximate to the nonaqueous outlet. In some embodiments, the aqueous phase weir can be configured to control the flow of the aqueous phase. In some embodiments, the aqueous phase weir can inhibit overflow of the non- aqueous phase to the aqueous phase.

[0386] In some embodiments, a volume of the second separator can depend on the density, viscosity, and coalescence properties of the aqueous phase and the nonaqueous phase. In some embodiments, the volume of the second separator is greater than the volume of the reactor. Greater volume of the second separator can provide sufficient residence time for droplet coalescence and phase separation. In some embodiments, the second separator can be about 2 times to about 5 times bigger than the reactor, inclusive of all values and ranges in between. In some embodiments, the second separator can be at least about 2 times, at least about 2.5 times, at least about 3 times, at least about 3.5 times, at least about 4 times, or at least about 5 times bigger than the reactor, inclusive of all values and ranges in between. In some embodiments, the second separator can be no more than about 5 times, no more than about 4.5 times, no more than about 4 times, no more than about 3.5 times, no more than about 3 times, no more than about 2.5 times, or no more than about 2 times bigger than the reactor, inclusive of all values and ranges in between. Combinations of the above-referenced ratios are also possible (e.g., at least about two times, and no more than about 5 times, or at least about 2.5 times and no more than about 5 times), inclusive of all values and ranges therebetween. In some embodiments, the second separator can be about 2 times, about 2.5 times, about 3 times, about 3.5 times, about 4 times, about 4.5 times, or about 5 times bigger than the reactor, inclusive of all values and ranges therebetween.

[0387] FIG. 3 illustrates hydrogenation reaction in a three phasic system, according to an embodiment. In some embodiments, the mediator 3610, for example, 2,6-dihydroxy anthraquinone (DHAQ) at pH 14 in the aqueous phase 3600 can be reduced to a reduced mediator 3620. In some embodiments, thePATENT

[0388] Attorney Docket No. 51198-070W02

[0389] reduction of the mediator 3610 can occur on the cathode side of an electrochemical cell 3200 or any other apparatus suitable for redox reaction. The reduction can be a partial or full reduction. In some embodiments, a reaction can occur on the opposite electrode, for example, anode of the electrochemical cell 3200. In some embodiments, the reaction on the anode of the electrochemical cell 3200 can involve HOR, or OER or any other proton-coupled oxidation reaction. The aqueous phase 3600 including the reduced mediator 3620 can contact the solid phase 3500 including the catalyst feed 3510, X.

[0390] In some embodiments, the reduced mediator 3620 can transfer electrons and / or hydrogen species to the solid phase 3500 including the catalyst 3510, X, thereby forming a hydrogen associated catalyst 3520, XH. In some embodiments, hydrogen associated catalyst 3520 refers to a catalyst that is associated with hydrogen at or near a surface of the catalyst, for example through adsorption, incorporation, or transient interactions, without requiring formation of a permanent chemical bond. Without wishing to be bound by theory, the term “catalyst” is intended to encompass the catalyst in any operative state, including an original state 3510, X, or a hydrogen associated state 3520, XH, and intermediate or transient states formed during operation.

[0391] The catalyst 3510 can be any catalyst described herein. Therefore, certain aspects of the catalyst 3510 are not described in detail herein. The solid phase 3500 including the hydrogen associated catalyst 3520, XH can contact the nonaqueous phase 3400. The nonaqueous phase 3400 can include the reactant 3410, for example styrene, dissolved in an organic solvent, for example, cyclohexene. In some embodiments, the organic solvent can be a solvent that exhibits weak interactions with the catalyst in either the original state 3510 or the hydrogenated state 3520. The organic solvent exhibiting weak interactions can substantially reduce adsorption of the organic solvent on the catalyst surface. In some embodiments, adsorption of organic solvent on the catalyst surface can deactivate the catalyst feed 3510, and inhibit hydrogenation of the reactant 3410. In other words, an organic solvent exhibiting weak interactions cannot substantially alter the oxidation state, lattice structure, surface morphology, and / or catalytic activity of the catalyst in either the original state or the hydrogenated state. Non-limiting examples of the organic solvent exhibiting weak interactions can include aliphatic hydrocarbons, cycloalkanes, and / or substituted hydrocarbons lacking coordinating functional groups.

[0392] In some embodiments, the solid phase 3500 including the hydrogen species associated catalyst 3520 can contact the nonaqueous phase 3400 including the reactant 3410 (e.g., styrene) which can cause hydrogenation of the reactant 3410 to form the hydrogenated product 3700, for example, ethylbenzene. The system for production of ethylbenzene from styrene showed a faradaic efficiency of about 100%. The hydrogenation system of the present invention can exhibit a high faradaic efficiency of at least about 90%, of at least about 91% at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, or at least about 99%, inclusive of all values and ranges in between.

[0393] FIG. 4 is a diagram of a continuous method for production of a hydrogenated product, according to an embodiment. The diagram illustrates that the system for hydrogenation of reactants can include a firstPATENT

[0394] Attorney Docket No. 51198-070W02

[0395] unit and a second unit. In some embodiments, the system can include a third unit. In some embodiments, the first unit can include an electrochemical cell 4200. In some embodiments, the electrochemical cell 4200 can be a single cell, stacked cells, flow cell, membrane electrode assembly, or any other suitable apparatus for electrochemical reduction of the mediator 4610 in a posolyte 4204. In some embodiments, the electrochemical cell 4200 can include a cathode 4203 and an anode 4201 , the posolyte 4204, a negolyte 4202, a power source 4208, and a membrane 4206. In some embodiments, electrochemical cell 4200 including the cathode 4203 and the anode 4201 , the posolyte 4204, the negolyte 4202, the power source 4208, and the membrane 4206 can be substantially similar to the electrochemical cell 2200 including the positive electrode 2203, the negative electrode 2201 , the posolyte 2204, the negolyte 2202, the power source 2208, and the separator membrane 2206, e.g., as described in FIG. 2. Therefore, certain aspects of the cathode 4203 and the anode 4201 , the posolyte 4204, the negolyte 4202, and the membrane 4206 are not described in detail herein.

[0396] In some embodiments, the mediator 4610, for example, DHAQ can be reduced to form the reduced mediator 4620, for example, DHAQ2'. In some embodiments, the reduced mediator 4620 can be partially or fully hydrogenated. In some embodiments, the mediator 4610 can formally receive two protons and two electrons to form the reduced mediator 4620 in the posolyte 4204. It will be understood that deprotonation of the reduced mediator may occur depending on the pH. In some embodiments, two OH- can transfer from the posolyte 4204 to the negolyte 4202 via the membrane 4206. In some embodiments, two OH- can release two electrons and produce oxygen in the negolyte 4202 compartment of the electrochemical cell 4200.

[0397] In some embodiments, at least a portion of the reduced mediator 4620 can be communicated to a second unit or reactor 4100 and form the aqueous phase 4600. In some embodiments, the second unit or reactor 4100 can include a physical location where the aqueous phase 4600 contacts the nonaqueous phase 4400. Although shown with the aqueous phase 4600 at the top of the separation section, the nonaqueous phase 4400 may be at the top if it is less dense than the aqueous phase. In some embodiments, the solid phase (including the catalyst) 4500 can be present within the aqueous phase 4600, within the nonaqueous phase 4400, and / or at an interface of the aqueous phase 4600 and the nonaqueous phase 4400. For example, the catalyst 4500a and 4500c can be present at the interface of aqueous phase 4600 and the nonaqueous phase 4400. For example, the catalyst 4500b and 4500d can be present within the nonaqueous phase 4400.

[0398] In some embodiments, contacting the aqueous phase 4600 including the reduced mediator 4620, the nonaqueous phase 4400 including the reactant, and the solid phase 4500 including the catalyst can cause hydrogenation of a reactant (for example, an unsaturated compound) within the nonaqueous phase 4400 and form the hydrogenated product and an oxidized mediator. In some embodiments, hydrogenation of the unsaturated compound can be facilitated by the catalyst in the solid phase 4500. In some embodiments, the reduced mediator 4620 can enable formation of the hydrogenated product. In some embodiments, hydrogenation of the unsaturated compound can occur via hydrogen transfer from the aqueous phase to the unsaturated compound. Hydrogen transfer can proceed through aPATENT

[0399] Attorney Docket No. 51198-070W02

[0400] direct chemical reaction, proton-coupled electron transfer, radical pathways, or other suitable hydrogenation mechanisms.

[0401] In some embodiments, the liquid-solid interface can be created through a suspension system or a fixed bed system in the reactor 4100. In some embodiments, the suspension system can include agitation of the first mixture including the aqueous phase 4600, the nonaqueous phase 4400, and the solid phase 4500. In some embodiments, the hydrogenation process is carried out in a fixed bed system in which the solid phase 4500 can be fixed relative to a flow path within the reactor 4100, such as a packed bed column, monolith, cartridge, or other suitable structures. The liquid phase, including the aqueous phase 4600, and the nonaqueous phase 4400 can be introduced into the fixed bed system either as a premixed biphasic liquid stream or as separate phases that are fed alternately or sequentially through the reactor 4100 including the fixed bed system. As the liquid stream passes through the fixed catalyst, contact can occur between the liquid phase and the solid phase 4500, enabling the desired hydrogenation reaction of the unsaturated compound to proceed via the reduced mediator 4620 and to produce the hydrogenated product and the oxidized mediator.

[0402] FIGS. 5A-5B illustrate a two-step hydrogenation, according to an embodiment. Without wishing to be bound by any particular theory, hydrogenation of an unsaturated compound can follow a two-step mechanism illustrated in FIGS 5A-5B. In some embodiments, the solid phase includes substantially the catalyst (e.g., Pd / C). In a first step as shown in FIG. 5A, an electron (ej can be transferred from the mediator, for example, 0.5 DHAQ2- to the surface of the catalyst 5500 within the aqueous phase 5600. Meanwhile, a water molecule can form a proton (or H+) and OFT. The proton from the water molecule can transfer to the surface of the catalyst 5510, for example, carbon loaded palladium (Pd / C), thereby forming a hydrogen associated catalyst 5520 (or proton-carrying catalyst).

[0403] FIG. 5B illustrates a second step of the two-step hydrogenation mechanism. In the second step, hydrogenation of a reactant 5410, the unsaturated compound, for example, R=R, can be facilitated by the hydrogen species associated catalyst 5520 (or proton-carrying catalyst) within the nonaqueous phase 5400. The proton (H+) can be transferred from the hydrogen species associated catalyst 5520 (proton-carrying catalyst) to the reactant (e.g., an unsaturated compound) 5410, for example R=R, thereby forming a hydrogenated product 5700, for example, RH-RH. The figure illustrates the process for transfer of a single hydrogen atom to the reactant, and it will be understood that transfer of two hydrogen atoms reduces the bond. In some embodiments, this mechanism can be referred to as proton-coupled electron transfer. In some embodiments, the two-step hydrogenation mechanism can involve transfer of a proton and an electron, transfer of chemisorbed atomic hydrogen (H«), hydride-like species (IT), and / or hydrogen atoms incorporated into reaction intermediates bound to the catalyst 5520.

[0404] In some embodiments, the first step and the second step of the two-step hydrogenation mechanism can occur in a coupled way, either concerted or stepwise. In some embodiments, the two-step hydrogenation mechanism can occur at the interface of the aqueous phase 5600 and the nonaqueous phase 5400. In some embodiments, agitation of the system can cause the catalyst 5500 transitioning between the aqueous phase 5600 and the nonaqueous phase 5400, thereby the proton transfer canPATENT

[0405] Attorney Docket No. 51198-070W02

[0406] occur between the aqueous phase 5600 and the nonaqueous phase 5400. In some embodiments, the catalyst 5500 can reside at the interface of the aqueous phase 5600 and the nonaqueous phase 5400. In some embodiments, the first step and the second step can be carried out in batch, continuous, or a semi-continuous operation.

[0407] FIG. 6 illustrates a solid phase 6500, including a surface modification, according to an embodiment. In some embodiments, the solid phase 6500 can include a catalyst body 6502, adjacent surface modifier 6504a, 6504b (collectively referred to as 6504), and hydrogen species 6506a, 6506b, 6506c (collectively referred to as 6506). The geometries shown are illustrative and non-limiting. For example, the catalyst body 6502 can be particulate, monolithic, porous, and / or nanostructured.

[0408] In some embodiments, the catalyst body 6502 can include one or more metals, metal oxides, metal sulfides, supported catalysts, porous catalysts, surface-modified catalysts, or combinations thereof. Suitable metals can include but are not limited to palladium (Pd), platinum (Pt), nickel (Ni), cobalt (Co), iron (Fe), rhenium (Re), rhodium (Rh), ruthenium (Ru), iridium (Ir), manganese (Mn), molybdenum (Mo), and copper (Cu). In some embodiments, the catalyst can include a porous metal catalyst such as Raney nickel or Raney copper. Any combination or alloy of the foregoing can also be used.

[0409] In some embodiments, the catalyst body 6502 can include a support material. Suitable supports can include carbon, activated carbon, graphite, carbon black, silica, alumina, titania, zirconia, zeolites, or combinations thereof. In certain embodiments, the support can include carbon, which can provide high surface area and enhanced dispersion of the catalytic metal.

[0410] In other embodiments, the catalyst 6500 can include a porous nickel or copper material prepared by leaching aluminum from a nickel-aluminum alloy or copper-aluminum alloy. Leaching can be performed using aqueous hydroxides (e.g., NaOH or KOH) to selectively remove aluminum, producing a high-surface-area, sponge-like metal structure.

[0411] In some embodiments, the solid phase 6500 can be referred to as a Janus solid catalyst. As used herein, a “Janus catalyst” or “Janus solid catalyst” refers to a solid phase including a catalyst and having at least two distinct regions or surfaces having different chemical and / or physical properties which can be configured to interact with different surrounding phases. In some embodiments, the surface modifier 6504 can alter the surface properties of the solid phase 6500 in a homogeneous or heterogeneous way. In some embodiments, the surface modifier 6504 can modify the surface of the solid phase 6500 such that the solid phase has at least two distinct regions, including a first region and a second region. In some embodiments, the first region can include the surface modifier 6504. The dashed-line convention indicates that the presence of occupancy of 6504a and 6504b may be transient, optional or state-dependent.

[0412] The first region of the solid phase 6500 can be different from the second region of the solid phase 6500 in chemical composition, physical properties, surface functionality, wettability, catalytic activity, and / or interaction with surrounding phases. The first region of the solid phase 6500 and the second region of the solid phase 6500 can perform different functions including but not limited to electronPATENT

[0413] Attorney Docket No. 51198-070W02

[0414] transfer, proton transfer, hydrogen association., adsorption of reactants, release of products, stabilization of reaction intermediates, mediation of mass or charge transport, phase transfer between immiscible phases, redox mediation, regulation of reaction selectivity, and / or regeneration of catalytic activity.

[0415] In some embodiments, the first region of the solid phase 6500 and / or the second region of the solid phase 6500 can exhibit different wettability characteristics, including hydrophilic, hydrophobic, and / or amphiphilic behavior. The first region of the solid phase 6500 can preferentially contact or be wetted by the aqueous phase including the reduced mediator. The second region of the solid phase 6500 preferentially can contact or be wetted by the nonaqueous phase, including the reactant. For example, the first region of the solid phase 6500 can interact with the mediator in any reduction state. For example, the second region of the solid phase 6500 can interact with the reactant.

[0416] In some embodiments, the solid phase 6500 can include multiple first regions and second regions. The distinct regions of the catalyst 6500 can be spatially separated, adjacent, partially overlapping, and / or oriented such that the distinct regions of the solid phase 6500 can preferentially interact with different phases, reactants, and / or intermediates. The distinct regions of the catalyst 6500 can be oriented relative to a direction of fluid flow, an electric field, a concentration gradient, and / or a phase boundary. The regions of the solid phase 6500 can be arranged such that each region preferentially contacts a different phase while remaining in functional communication with another region.

[0417] Hydrogen species 6506b and 6506c are shown as “H” labels connected to the surface of the catalyst body 6502, representing surface-associated hydrogen. Without limitation, hydrogen species 6506b and 6506c may correspond to chemisorbed atomic hydrogen (H«), hydride-like species (H“) stabilized by a catalyst lattice, proton-electron pairs resident at adjacent sites, or hydrogen atoms incorporated into reaction intermediates bound to the catalyst body 6502. The angular dispositions of 6506b and 6506c are schematic and not indicative of actual coordination geometry.

[0418] Hydrogen species 6506a is shown as a dashed rectangle containing “H” spaced from the surface of the catalyst body 6502. In various embodiments, 6506a represents (i) desorbed hydrogen (e.g., Hz) departing the surface, (ii) a mobile hydrogen species migrating across the support or to / from a promoter phase (e.g., hydrogen spillover or reverse spillover), or (Hi) a product-bound hydrogen in a nascent state of desorption. The dashed-line rectangle indicates non-permanent association or state change (e.g., transition from adsorbed to desorbed). For example, the surface associated hydrogen species 6506a can represent a hydrogen atom in a partially or fully desorbed state.

[0419] In some embodiments, the arrangement of the surface modifier 6504, and hydrogen species 6506 can enable hydrogenation / dehydrogenation transformations, hydrogen activation, and / or hydrogen transfer between distinct surface sites. In some embodiments, hydrogen species 6506 can facilitate selective hydrogenation, with 6506a representing a hydrogen equivalent (or reducing equivalent) configured to transfer to a reactant (e.g., unsaturated compound).

[0420] In some embodiments, the solid phase 6500 described herein can be stabilized at or near the interface between the aqueous phase and the nonaqueous phase. The solid phase 6500 can facilitatePATENT

[0421] Attorney Docket No. 51198-070W02

[0422] transportation of the electro-proton pair, a charge neutral fragment, from the aqueous phase into the nonaqueous phase. The solid phase 6500 described herein can significantly reduce the phase transfer issue and facilitate hydrogen transfer from the mediator to the reactant. The solid phase 6500 described herein can enhance the contact area of the aqueous phase, the nonaqueous phase, and the solid phase (or catalyst), thereby improving mass transport and reaction rates compared to conventional catalysts.

[0423] The solid phase 6500 described herein can improve stability, reduce aggregation, and / or alter phase affinity. The solid phase 6500 described herein can enhance a collision frequency between the aqueous mediator and the reactant, thereby significantly improve mass transport, increase interfacial localization, reduce waste generation, and / or improve selective hydrogenation. The solid phase 6500 described herein can provide advantages with respect to electrochemical efficiency.

[0424] FIG. 7 illustrates schematic representation of localization of a solid phase, according to an embodiment. The solid phase 7500a, 7500b, 7500c, 7500d, can include a catalyst body 7502a, 7502b, 7502c, 7502d, and a surface modifier 7504a, 7504b, 7504c, 7504d. The catalyst body 7502 and the surface modifier 7504 can be substantially similar to the catalyst body 6502 and the surface modifier 6504. Therefore, certain aspects of the catalyst body 7502 and the surface modifier 7504 are not described in detail herein. The solid phase 7500 can be localized at the interface of the aqueous phase 7600 and the nonaqueous phase 7400. In some embodiments, the solid phase 7500 can be present within the aqueous phase 7600. In some embodiments, the solid phase 7500 can be present within the nonaqueous phase 7400.

[0425] In some embodiments, surface modifier 7504 such as PTFE can improve compatibility with nonaqueous phase, enhance catalyst mobility at phase boundaries, and / or promote interfacial catalysis involving both aqueous and nonaqueous phase components. Surface modification can be achieved through ball milling, thermal lamination, grafting, dispersion coating, plasma based deposition, or other suitable techniques.

[0426] FIG. 8 illustrates the effect of catalyst surface modification on localization of the solid phase. In the left panel, two centrifuge tubes are shown including two immiscible liquid phases, an aqueous phase (KOH) and a nonaqueous phase (hexane) without agitation (e.g., still condition). The upper phase, labeled as hexane is the nonaqueous phase and the lower phase, labeled as KOH is the aqueous phase. Black particulates are the catalyst. The upper tube includes the solid phase with PTFE. As shown, the solid phase with PTFE favors the interphase of the aqueous phase and the nonaqueous phase. The bottom tube includes the solid phase without PTFE solid phase. As shown, the solid phase without PTFE favors the aqueous phase.

[0427] In the right panel, two centrifuge tubes are shown including two immiscible liquid phases, an aqueous phase (KOH) and a nonaqueous phase(hexane) after agitation (e.g., after shaking). The upper tube includes the solid phase with PTFE. As shown, the solid phase with PTFE favors the interphase of the aqueous phase and the nonaqueous phase. The bottom tube includes the solid phase without PTFE modification. As shown, the solid phase without PTFE favors the aqueous phase.PATENT

[0428] Attorney Docket No. 51198-070W02

[0429] FIG. 9 illustrates electrochemical potential diagram of mediators 961 Oa, 961 Ob, 961 Oc, 961 Od, unsaturated compounds 9410a, 941 Ob, 941 Oc, 941 Od, 941 Oe, 941 Of, 941 Og, 941 Oh, and hydrogenated products 9700a, 9700b, 9700c, 9700d, 9700e, 9700f, 9700g, 9700h, according to an embodiment. Central arrow represents a progression in measured potentials with various compounds positioned according to their corresponding electrochemical potentials. The upper row shows various mediators including DHPS 961 Od with a measured potential of -0.446 V, BHPC 961 Oc with a measured potential of 0.004 V, DHAQ 9610b with a measured potential of 0.116 V, and DPPEAQ 9610a with a measured potential of 0.329 V. The redox potential of the mediators DPPEAQ 9610a, DHAQ 9610b, BHPC 9610c, and DHPS 961 Od were measured using cyclic voltammetry as shown in FIG. 10.

[0430] Underneath the central arrow, a serious of reactants (or unsaturated compounds), 9410a, 9410b, 9410c, 941 Od, 9410e, 9410g, and 941 Oh (collectively referred to as 9410) and the corresponding hydrogenated product, 9700a, 9700b, 9700c, 9700d, 9700e, 9700f, 9700g, and 9700h (collectively referred to as 9700) are shown along their corresponding potential.

[0431] In some embodiments, the mediator DPPEAQ 9610a exhibits a standard reduction potential of 0.329 V vs. RHE, which is substantially more positive than Vupd. Without being bound by theory, mediators having potentials above VuPd may not provide a sufficient driving force to reduce the catalyst surface, e.g., surface palladium species, and thereby generate surface-associated hydrogen species, Hads. Under such conditions, the mediator DPPEAQ 9610a may not support hydrogenation of a reactant with the present system including Pd / C as the catalyst.

[0432] However, in other embodiments, a catalyst having a higher VuPd such as a nickel based catalyst, a platinum based catalyst, or another catalyst with comparable surface redox characteristics can be employed. For such catalysts, DPPEAQ 9610a can support hydrogenation of the reactant.

[0433] Accordingly, compatibility of a given mediator with a particular catalyst can depend on the relative values of the mediator’s standard reduction potential and the catalyst’s VuPd. Therefore, mediators such as DPPEAQ 9610a can be effective in the systems utilizing catalyst whose VuPd is sufficiently positive to allow thermodynamic driving for surface reduction and hydrogen formation.

[0434] In contrast, DHAQ, BHPC, DHPS have reduction potentials more negative than VuPdOf Pd. Such alignment indicates that these mediators having a reduction potential more negative VuPd can thermodynamically facilitate formation of surface-associated hydrogen on the catalyst surface (e.g., Pd / C surface) and therefore function as effective hydrogen donors.

[0435] To evaluate substrate compatibility, the reduction potentials for the mediators were compared with calculated standard potentials of representative unsaturated compounds obtained via density functional theory (DFT). This analysis demonstrates that unsaturated compounds, including styrene (0.358 V) and terminal alkynes (0.512 V-0.665 V), exhibit relatively positive reduction potentials well above the VuPd, suggesting that their reduction is thermodynamically favorable once the initial barrier of hydrogen deposition is overcome, for Pd / C. Under such conditions, the mediators DHPS 961 Od, BHPC 9610c, and DHAQ 9610b can be efficient in hydrogenation of the unsaturated compounds having relatively positive reduction potentials above the VuPd.PATENT

[0436] Attorney Docket No. 51198-070W02

[0437] As shown in FIG. 9, the mediators DHPS 961 Od, BHPC 961 Oc, and / or DHAQ 961 Ob can be used for reduction of unsaturated compounds including double bonds and triple bonds. Systems and methods described herein can enable hydrogenation of cyclic alkene, e.g., cyclohexene 941 Od, to form a hydrogenated product cyclohexane 9700d. In some embodiments, the mediators described herein can facilitate partial hydrogenation of unsaturated compounds. For example, compound 1 -hexyne 941 Og, which contains a carbon-carbon triple bond can be partially hydrogenated to form a double bond containing product such as 1 -hexene 9700g. Similarly, unsaturated compounds including aromatic rings, such as phenylacetylene 941 Oh can be converted to corresponding partially hydrogenated products, such as styrene 9700h. In addition, compounds containing triple bonds, such as 1 -hexyne 941 Of, can be fully hydrogenated using the mediators described herein and afford a hydrogenated product, such as hexane 9700f. In some embodiments, partial hydrogenation of the unsaturated compound can be achieved via a mediator with a more positive redox potential and / or using an alternative catalyst such as copper based catalysts. Accordingly, the extent of hydrogenation of the unsaturated compound, whether partial or complete, can be controlled through selection of a suitable catalyst and mediator.

[0438] Carbonyl containing compounds such as 4-tert-butylbenzaldehyde 9410a and acetophenone 9410b exhibit reduction potentials that approach or fall below those of the weaker mediators in the series. These reduction potential values can indicate that reducing mediators with more negative reduction potential, such as DHPS 961 Od and / or BHPC 9610c, may be favorable for the reduction of carbonyl compounds under the same catalytic conditions.

[0439] The hydrogenation methods and system described herein were used for hydrogenation of an alkyne, phenylacetylene 941 Oe. Although not shown, phenylacetylene 941 Oe exhibited low conversion across all mediators despite possessing a relatively positive theoretical reduction potential. Without limiting the invention to any specific mechanism, this behavior may be influenced by kinetic factors associated with alkyne adsorption or surface transformation pathways. However, for cyclohexene, a nonconjugated alkene, the system including DHAQ as the mediator showed low conversion, whereas the system including the mediators with more negative reduction potential, BHPC and DHPS achieved high conversion, suggesting that non-conjugated double bonds desire the higher activity of hydrogen generated at more negative potentials.

[0440] The hydrogenation methods and system described herein were used of hydrogenation of a cycloalkene, cyclohexene 941 Od. Although not shown, cyclohexene 941 Od showed low conversion with the mediator, DHAQ, whereas mediators having more negative potential, BHPC and DHPS achieved high conversion of cyclohexene 941 Od. Without wishing to be bound by theory, it can suggest that non-conjugated double bonds desire the higher activity of hydrogen generated at more negative potentials.

[0441] FIG. 10 illustrates cyclic voltammograms of selected mediators and a catalyst. Cyclic voltammetry (CV) was employed to determine the redox potentials of four mediators, DPPEAQ, DHAQ, BHPC, and DHPS relative to the hydrogen adsorption behavior of a carbon loaded palladium (Pd / C) catalyst.PATENT

[0442] Attorney Docket No. 51198-070W02

[0443] Each mediator exhibits a characteristic redox wave within the potential window spanning approximately -0.5 V to +1 .0 V vs. RHE.

[0444] A series of vertical dashed lines is positioned near the center of FIG. 10. These dashed lines correspond to the measured reduction potentials of the individual mediators and reference potential Vupd, indicating the onset potential associated with hydrogen underpotential deposition on the catalyst. The CV data identify a characteristic potential associated with the onset of hydrogen deposition on the catalyst, Pd / C, corresponding to the underpotential deposition of hydrogen (UPDH). UPDH is what happens when hydrogen deposits onto a metal surface at a potential more positive than the equilibrium (Nernst) potential for bulk deposition.

[0445] The underpotential deposition potential (Vupd) was measured to be 0.149 V vs. RHE. This value establishes a reference point that defines whether a given mediator possesses sufficient driving force to generate surface-associated hydrogen species, Hads on the catalyst surface.

[0446] The mediator voltammograms appear clustered around the region bracketed by their respective dashed-line potentials. The trace for DPPEAQ extends into more positive potentials, while DHAQ, BHPC, and DHPS exhibit features progressively shifted toward more negative values. The catalyst (Pd / C) voltammogram spans the full potential range. Overall, the figure visually compares (i) the redox potentials of the mediators, (ii) their electrochemical currents under cyclic voltammetry, and (Hi) their alignment relative to the hydrogen underpotential deposition threshold of the catalyst. The difference in peak positions, peak shape, and current magnitude among the mediators and the catalyst illustrate tunable electrochemical behavior that may be leveraged in selective hydrogenation process.

[0447] FIG. 11 illustrates hydrogenation rate for a molecule-driven condition and a potential-driven condition. To evaluate the contribution of electrochemical driving force in the disclosed system, a comparative control experiment was performed. A “potential-driving” configuration was constructed in which an external voltage equivalent to the measured open-circuit voltage (OCV) of the reduced DHAQ mediator was applied directly to the catalyst in the absence of the mediator. The performance of this “potential-driving” configuration was compared to that of a “molecule-driving” configuration containing the reduced mediator DHAQ2-.

[0448] As shown, the rates of hydrogenation in the two configurations were of similar magnitude, with the “molecule-driving” configuration producing hydrogen at a hydrogenation rate of about 0.364 mmolZ(L-min) and the “potential-driving” configuration producing hydrogen at the hydrogenation rate of about 0.274 mmolZ(L-min). The similarity in these hydrogenation rates can indicate that application of a potential equivalent to the open circuit voltage (an equilibrium potential of the mediator under zerocurrent conditions) of the reduced mediator provides a driving force comparable to that supplied by the mediator itself. Without being bound by any particular theory, these results can suggest that the catalytic hydrogenation rate is governed by the potential established at the catalyst surface, whether supplied electrochemically or through a reduced redox species. In other words, it can suggest that chemical and electrical driving force can be equivalent.PATENT

[0449] Attorney Docket No. 51198-070W02

[0450] FIGS. 12A shows the effect of catalyst mass (e.g., catalyst load) on hydrogenation rate over time. The effect of macroscopic transport phenomena on hydrogenation rate of the unsaturated compound was studied. Different hydrodynamic parameters were studied to identify the dominant rate-limiting factors in the disclosed hydrogenation system. The Pd / C / PTFE catalyst here was used which is surface modified carbon loaded palladium, Pd / C. The effect of catalyst mass was evaluated using the mediator, DHAQ and the reactant, styrene, as a representative model. FIG. 12A shows that higher concentrations of the surface modified catalyst, Pd / C / PTFE, can result in correspondingly higher reaction rates. For example, 5 mg of Pd / C / PTFE can afford a hydrogenation rate of about 0.102 mmol / (L-min) for styrene while, 25 of mg Pd / C / PTFE can afford a hydrogenation rate of about 1.176 mmol / mmol / (L-min). This suggests that the total reaction rate may scale with the available catalytic surface area.

[0451] FIG. 12B shows the effect of stirring rate on hydrogenation rate over time. The effect of stirring rated was evaluated using the mediator, DHAQ and the reactant, styrene, as a representative model. As shown in FIG. 12B hydrogenation rate can be significantly improved by increasing agitation speed. Hydrogenation rate increases substantially as the stirring rate is raised from 200 to 1 ,000 rpm. For example, a stirring rate of about 1 ,000 rpm shows a hydrogenation rate of about 1.176 mmol / (L-min), a stirring rate of about 600 rpm shows a hydrogenation rate of about 0.273 mmol / (L -min), and a stirring rate of about 200 rpm shows a hydrogenation rate of about 0.073 mmol / (L-min). In certain embodiments, sensitivity to mixing conditions can be consistent with a regime in which external mass-transfer processes influence the overall rate. In some embodiments, an increased convective motion can reduce boundary-layer thickness and improve transport of the organic substrate to the catalyst surface.

[0452] FIG. 12C shows the effect of mediator on hydrogenation rate of styrene over time. A set of hydrogenation reactions was performed. Control experiments (not shown) conducted in the absence of the Pd / C / PTFE catalyst resulted in no detectable formation of reduced products for any mediatorsubstrate combination. Without wishing to be bound by any particular theory, these observations indicate that direct electron transfer from the aqueous mediator to the substrate does not occur and that the catalyst is desired to mediate substrate reduction through surface associated hydrogen species.

[0453] Consistent with the CV results, systems employing DPPEAQ produced only trace or undetectable quantities of reduced products across all substrates evaluated. Although the reduction potential of DPPEAQ exceeds that of certain substrates (e.g., styrene), its potential remains insufficient to surpass the VuPd threshold for Pd / C, thereby preventing the formation of catalytically active hydrogen species.

[0454] The remaining mediators, DHAQ, BHPC, and DHPS, exhibited activity trends that correlate with their relative reduction potentials. Complete conversion of styrene was observed with all three mediators, consistent with the favorable thermodynamic relationship between mediator potential, formation of surface-associated hydrogen, Hads, and substrate reduction potential. As shown, the reaction rate obtained with DHPS is greater than that obtained with BHPC which in turn is greater than thatPATENT

[0455] Attorney Docket No. 51198-070W02

[0456] obtained with DHAQ. This trend is consistent with the observation that the mediators having more negative redox potential can provide increased driving force for generation of surface-associated hydrogen species and consequently, higher hydrogenation rate.

[0457] FIGS. 13A-C illustrate the effect of the mediator concentration, the reactant concentration, and state of charge (SOC) on hydrogenation of a reactant, styrene. FIG. 13A shows the effect of concentration of the mediator (DHAQ) in the aqueous phase on reaction rate. Hydrogenation reaction exhibits zeroorder kinetics with respect to the concentration of the mediator, as the reaction rate remains significantly unchanged while the concentration of the mediator is increased from 0.25 M to 0.5 M. FIG. 13B shows the effect of styrene concentration on hydrogenation of styrene. The production time plots indicate that hydrogenation of styrene follows zero-order kinetics with respect to the concentration of the reactant. This behavior is consistent with a system in which the catalytic surface is populated with active species, and the overall rate is influenced by a surface-associated step, such as a surface reaction or an interfacial phase-transfer process, rather than by bulk diffusion.

[0458] FIG. 13C shows the effect of SOC on hydrogenation of styrene. Production is plotted against time for two distinct SOC, 70% and 30%. Both curves exhibit an initial linear increase in product formation followed by a gradual leveling. As shown, increasing the SOC can cause a measurable increase in the reaction rate from 0.912 mmol / (L-min) to 1.176 mmol / (L-min). Since the SOC directly dictates Nernstian potential of the redox solution, higher SOC corresponds to a more negative reducing potential. Without wishing to be bound by any particular theory, it can indicate that the reaction is not controlled by quantity of molecules but by the driving force (redox potential). A more negative potential at higher SOC likely increases the coverage or activity of surface-associated hydrogen species on the catalyst surface, thereby accelerating the reaction (hydrogenation). Without wishing to be bound by any particular theory, these kinetic data can indicate that the reaction proceeds under potential-controlled conditions, exhibiting zero-order behavior with respect to a reactant concentration and a mediator concentration. The aqueous phase including the mediator can establish an adjustable electrochemical potential that governs the rate of surface hydrogen generation and thereby regulates the overall hydrogenation activity.

[0459] FIGS. 14A-14C illustrate the effect of different mediators on hydrogenation of different unsaturated compounds. Three unsaturated compounds, benzaldehyde (an aldehyde compound), acetophenone (a ketone compound), and styrene, were examined in combination with three mediators (DHAQ, BHPC, and DHPS). As shown, the hydrogenation rate for benzaldehyde, acetophenone, and styrene increases as the reduction potential of the mediator becomes more negative.

[0460] Reductions of benzaldehyde and acetophenone as shown in FIG. 14A and FIG. 14B reflect the DFT predictions: DHAQ provided limited conversion, BHPC provided moderate conversion, and DHPS, the mediator with the most negative reduction potential, achieved high conversion in both cases. FIG. 14C indicates substantially full conversion of styrene with all three active mediators. The measured rate increases from 1.176 rnml / (L-min) when DHAQ is used to 4.0003 mml / (L-min) when DHPS is employed. These results demonstrate that the mediator potential provides an effective means of adjusting reaction velocity and that mediators with increasingly negative potentials yield progressivelyPATENT

[0461] Attorney Docket No. 51198-070W02

[0462] higher hydrogenation rates across both alkene and carbonyl substrates. Without wishing to be bound by any particular theory, a correlation can exist between the electrochemical characteristics of the mediator and the hydrogenation reaction.

[0463] FIGS. 14A-14C demonstrate that the reactivity of the mediator-substrate system follows a thermodynamic progression in which the mediator potential is sufficiently negative to enable formation of surface associated hydrogen species on the Pd / C catalyst. This demonstrates that the mediator can further provide enough driving force to reduce the selected organic substrate.

[0464] FIG. 15 shows the in situ X-ray diffraction (XRD) cell setup for monitoring the hydrogenation process. To evaluate structural changes associated with potential-dependent hydrogen uptake, in situ X-ray diffraction (XRD) measurements were performed on the Pd / C catalyst under operating conditions. A custom flow cell was employed to allow real-time monitoring of diffraction features while reduced mediators of differing potentials were circulated over the catalyst. The cell includes a Pd / C catalyst. The aqueous mediators or the reactant in the nonaqueous phase are pumped through the catalyst. FIG. 16 shows the XRD results for a catalyst sample exposed to various mediators or to a reactant using the setup described in FIG. 15. Each diffractogram exhibits a diffraction feature having a Bragg angle (20) of between approximately 38° and 42°, corresponding to Pd (111) reflection, and a second feature having a Bragg angle (20) of between approximately 43° and 47°, consistent with higher-order palladium reflections. The resulting diffractograms show that exposure to the reduced mediators produces a measurable shift of the Pd (111) reflection toward lower 20 values relative to control measurements obtained using pure styrene or aqueous electrolyte. In addition, mediators having more negative potential produce a greater shift toward lower degree 20 values.

[0465] The magnitude of the observed peak shift varies with the measured potential of the mediator, with larger shifts occurring when mediators of more negative potential are used (DHAQ < BHPC < DHPS). Such shifts are consistent with lattice expansion of the catalyst, palladium phase. As used herein, the term, “lattice expansion” refers to an increase in the spacing between atoms in a crystalline solid relative to the equilibrium lattice parameters. Lattice expansion can arise from interstitial incorporation of small atoms (e.g., hydrogen species), changes in electronic structure and / or charge density (e.g., electron uptake or electron donation), formation of metal hydride phases, and / or thermal or mechanical influences. Accordingly, a shift of the palladium diffraction peak toward lower 20 degree can indicate increased incorporation of hydrogen species within the catalyst lattice. Increased incorporation of hydrogen species can enhance the reaction rate under the conditions described. These results can indicate that the structural response of the Pd lattice depends on the potential established by the mediator and that mediators of increasingly negative potential induce correspondingly greater lattice expansion under the conditions tested.

[0466] Furthermore, when the catalyst is exposed to a reactant such as styrene, the resulting diffractogram exhibits a Pd(111) peak position that is substantially similar to the untreated catalyst Pd / C. This observation can indicate that the hydrogen species previously incorporated into, or present on the palladium lattice are consumed during the hydrogenation of styrene under the experimental conditions. As these hydrogen species are consumed, the palladium lattice returns toward itsPATENT

[0467] Attorney Docket No. 51198-070W02

[0468] equilibrium spacing, resulting in a diffraction signature that substantially matches that of the untreated Pd / C catalyst.

[0469] These observations further support that the palladium surface and / or near surface lattice can act as a reversible hydrogen reservoir, with stored hydrogen participating in the subsequent hydrogenation reaction. The restored peak position in the presence of styrene thus reflects depletion of hydrogen species through reaction, confirming that hydrogen species introduced via the reduced mediator are chemically accessible and reactive under the tested conditions. Without being bound by any particular theory, these results are consistent with a mechanism in which the reduced mediator can facilitate transfer of hydrogen species to the palladium catalyst, leading to transient formation of palladium hydride-like phases or partial occupation of interstitial lattice sites.

[0470] FIG. 17 shows a flow diagram of a method 10 for hydrogenation of an unsaturated compound, according to an embodiment. As shown in FIG. 17, the method 10 can employ the system 1000, any components (e.g., reactor 1100, electrochemical cell 1200, separator 1300, nonaqueous phase 1400, solid phase 1500, aqueous phase 1600), and / or features thereof as described with respect to FIG. 1. It should be noted that step 12 is optional and may not be performed when a reduced mediator is otherwise available. In addition, steps 20, 22, and 24 are likewise optional if separation and recycling are not desired. While the method 10 and operations thereof have been described herein with respect to the system 1000, in some embodiments, the method 10 or operations thereof may be performed by any suitable system described herein. All such variations are envisioned herein and should be considered as part of the present disclosure. For example, the method 10 may be employed using a reactor not fluidically coupled to an electrochemical cell. In such embodiments, liquid transfers may be manual. In another example, the reactor may act as part of the electrochemical cell, e.g., during a batch process.

[0471] The method 10 can be employed for the unsaturated compound including at least one multiple bond between atoms, including but not limited to a carbon-carbon double bond, carbon-carbon triple bond, a carbon-heteroatom multiple bonds. In some embodiments, the unsaturated compound can include reducible nitrogen containing compound such as an azo compound, a nitro compound, a nitrene compound, a hydroxylamine compound, a hydroxamic acid compound, a nitrite compound, a nitrile compound, a nitroso compound, or an N-oxide compound. The unsaturated compound can include any compound containing at least one bond capable of undergoing addition of hydrogen or electrons. The unsaturated compound can include any reactant containing a multiple bond (e.g., C=C, C=C, C=O, C=N, N=O, or C=N) species.

[0472] In some embodiments, the method 10 can optionally include reducing a mediator in an aqueous phase 1600, at step 12. In some embodiments, the mediator can be reduced to a reduced mediator (or mediator in the reduced state) in an electrochemical cell 1200. In some embodiments, the reduction of the mediator can include receiving one or more electrons. In some embodiments, the reduced mediator can serve as a reversible hydrogen carrier, undergoing electroreduction to store one or more hydrogen species or hydrogen equivalents, which can subsequently be delivered to the reactant.PATENT

[0473] Attorney Docket No. 51198-070W02

[0474] In some embodiments, the electrochemical cell 1200 can include a single cell, stacked cells, flow cell, membrane electrode assembly, or any other suitable structure for electrochemical reduction of the mediator. In some embodiments, the electrochemical cell 1200 can operate in an aqueous phase 1600, although combined aqueous-nonaqueous phase 1400 are also contemplated. In some embodiments, the reduction of the mediator is not limited to the electrochemical process and may occur via chemical, catalytic, photochemical, thermal, or other redox mechanisms.

[0475] In some embodiments, the electrochemical cell 1200 can include a cathode, an anode, and a separator membrane. In some embodiments, the reduction of the mediator can occur at the cathode. In some embodiments, the cathode is contacted with the aqueous phase 1600 while an electrical potential is applied. In some embodiments, the aqueous phase 1600 can include the mediator. In some embodiments, an oxygen evolution reaction (OER) and / or hydrogen oxidation reaction (HOR) can occur at the anode.

[0476] In some embodiments, protons generated in a posolyte can migrate through the membrane to a negolyte, where the protons participate in the reduction of the mediator to form the reduced mediator. In some embodiments, the membrane is a size-exclusion membrane configured to permit proton transport while limiting crossover of the mediator or other redox-active species. In some embodiments, the membrane is a proton-exchange membrane (PEM) configured to permit proton transport while limiting crossover of other ions or materials. In some embodiments, the mediator can include one of vanadium complexes, chromium complexes, phenazines, quinoxalines, anthraquinones, naphthoquinones, benzoquinones, fluorenones, azo compounds, phenoxazines, phenothiazines, alloxazines, isoalloxazines, bipyridiniums (viologens), and / or any other suitable mediator described herein. In some embodiments, the mediator can be soluble in an aqueous phase 1600 to mediate hydrogenation of an unsaturated compound present in a nonaqueous phase 1400. The method 10 can further include contacting the aqueous phase 1600 including the mediator in the reduced state to the nonaqueous phase including the unsaturated compound, and the solid phase including a catalyst, at step 14. In some embodiments, the contact of the aqueous phase 1600, the solid phase 1500, and the nonaqueous phase 1400 can occur in a reactor 1100. In some embodiments, the contacting can be implemented via an agitator (e.g., a stirrer). In some embodiments, the agitator can be disposed in the reactor 1100.

[0477] In some embodiments, the method 10 can further include allowing a hydrogen species transfer to occur via the mediator in the reduced state and hydrogenation of an unsaturated organic compound, in presence of the catalyst to form a hydrogenated product and regenerate the mediator (e.g., hydrogenation of the unsaturated organic compound, at step 16, as described herein). In some embodiments, agitation of the aqueous phase 1600, the nonaqueous phase1400, and the solid phase 1500 can allow the hydrogenation reaction to occur.

[0478] In some embodiments, the aqueous phase 1600, the solid phase 1500, and the nonaqueous phase 1400 can form a first mixture. In some embodiments, the first mixture can be transferred to a separator 1300. In some embodiments, the method 10 can further include separating the solid phase 1500 from the first mixture of the aqueous phase, the nonaqueous phase, and the solid phase, at stepPATENT

[0479] Attorney Docket No. 51198-070W02

[0480] 18. In some embodiments, the separation of the solid phase 1500 can occur in a first separator (e.g., the first separator 2310). In some embodiments, the method 10 can further include communicating the separated solid phase to the contacting operation 14, at 20 (e.g., returning the separated solid phase to the reactor 1100, 2100.

[0481] In some embodiments, the separation of the solid phase 1500 from the first mixture can form a second mixture including an aqueous phase 1600 and a nonaqueous phase 1400. In some embodiments, the second mixture can be transferred to a second separator (e.g., the second separator 2320). In some embodiments, the method 10 can further include separating the aqueous phase 1600 from the mixture of the aqueous phase and the nonaqueous phase, at step 22. In some embodiments, the separation of the solid phase, the aqueous phase, and the nonaqueous phase can occur within the reactor once the hydrogenation reaction is complete. In some embodiments, the separation of the solid phase, the aqueous phase, and the nonaqueous phase can occur in a single separator. In some embodiments, separation of the solid phase, the aqueous phase, and the nonaqueous phase can occur in the reactor (e.g., the reactor 1100, 2100). In some embodiments, the method 10 can further include communicating the separated aqueous phase to the electrochemical cell 1200, at step 24. In some embodiments, the separated aqueous phase can include the oxidized mediator. In some embodiments, the oxidized mediator can be regenerated in the electrochemical cell 1200.

[0482] In some embodiments, method 10 can further include allowing a redox reaction to occur between the solid phase including a catalyst and a nitrogen-containing compound to form a partially reduced or a fully reduced product (e.g., partially reduced nitrogen-containing product or fully reduced nitrogencontaining product e.g., fully hydrogenated nitrogen-containing product), at step 16. In some embodiments, the resulting product of step 16 can include the at least one of the partially reduced or the fully reduced nitrogen-containing product. In some embodiments, the partially reduced nitrogencontaining product can include a hydroxyl amine (-NHOH), an azoxy (-N=N+(O ), a hydrazo (-NH-NH-), or a nitroso (-NO) compound. In some embodiments, the fully reduced nitrogen-containing product can include an amine (-NH2).

[0483] Various concepts may be embodied as one or more methods, of which at least one example has been provided. The acts performed as part of the method may be ordered in any suitable way.

[0484] Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments. Put differently, it is to be understood that such features may not necessarily be limited to a particular order of execution, but rather, any number of threads, processes, services, servers, and / or the like that may execute serially, asynchronously, concurrently, in parallel, simultaneously, synchronously, and / or the like in a manner consistent with the disclosure. As such, some of these features may be mutually contradictory, in that they cannot be simultaneously present in a single embodiment. Similarly, some features are applicable to one aspect of the innovations, and inapplicable to others.PATENT

[0485] Attorney Docket No. 51198-070W02

[0486] It should be understood that advantages, embodiments, examples, functional, features, logical, operational, organizational, structural, topological, and / or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the embodiments or limitations on equivalents to the embodiments. Depending on the particular desires and / or characteristics of an individual and / or enterprise user, database configuration and / or relational model, data type, data transmission and / or network framework, syntax structure, and / or the like, various embodiments of the technology disclosed herein may be implemented in a manner that enables a great deal of flexibility and customization as described herein.

[0487] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms. As used herein, in particular embodiments, the terms “about” or “approximately” when preceding a numerical value indicates the value plus or minus a range of 10%. Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the disclosure. That the upper and lower limits of these smaller ranges can independently be included in the smaller ranges is also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure.

[0488] The phrase “and / or,” as used herein in the specification and in the embodiments, should be understood to mean “either or both” of the elements so conjoined, i.e. , elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0489] As used herein in the specification and in the embodiments, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the embodiments, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e., “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the embodiments, shall have its ordinary meaning as used in the field of patent law.PATENT

[0490] Attorney Docket No. 51198-070W02

[0491] As used herein in the specification and in the embodiments, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a nonlimiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and / or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0492] In the embodiments, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

[0493] While specific embodiments of the present disclosure have been outlined above, many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the embodiments set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the disclosure. Where methods and steps described above indicate certain events occurring in a certain order, those of ordinary skill in the art having the benefit of this disclosure would recognize that the ordering of certain steps may be modified and such modification are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process, when possible, as well as performed sequentially as described above. The embodiments have been particularly shown and described, but it will be understood that various changes in form and details may be made.

Claims

1. PATENTAttorney Docket No. 51198-070W02Claims1. A method, comprising:contacting an aqueous phase comprising a mediator in a reduced state, a nonaqueous phase including an unsaturated compound, and a solid phase including a catalyst, to afford a hydrogenated product and the mediator in an oxidized state.

2. The method of claim 1 , wherein affording the hydrogenated product and the oxidized mediator is via hydrogenation of the unsaturated compound and oxidation of the mediator in the reduced state, the hydrogenation and oxidation facilitated by the catalyst.

3. The method of claim 1 or 2, wherein a hydrogen species is transferred from the mediator in the reduced state to the unsaturated compound.

4. The method of any one of claims 1 -3, wherein the catalyst is a metal, a metal oxide, or a metal sulfide catalyst comprising at least one of palladium (Pd), platinum (Pt), nickel (Ni), cobalt (Co), iron (Fe), rhenium (Re), rhodium (Rh), ruthenium (Ru), iridium (Ir), manganese (Mn), molybdenum (Mo), and copper (Cu).

5. The method of claim 4, wherein the catalyst includes a support coupled to at least one of the metal, the metal oxide, or the metal sulfide.

6. The method of claim 5, wherein the support includes carbon.

7. The method of any one of claims 4-6, wherein the catalyst comprises nickel or copper and has a porous structure, the porous structure formed by leaching aluminum from a nickel-aluminum alloy or a copper-aluminum alloy.

8. The method of any one of claims 1 -6, wherein the catalyst includes Pd / C.

9. The method of any one of claim 1-8, wherein the solid phase is amphipathic.

10. The method of any one of claims 1 -9, wherein the solid phase at least partially localizes at an interface between the aqueous phase and the nonaqueous phase.

11. The method of any one of claims 1 -10, wherein the solid phase comprises polytetrafluoroethylene (PTFE).

12. The method of any one of claims 1-11, wherein the mediator comprises at least one of a phenazine, quinoxaline, anthraquinone, naphthoquinone, benzoquinone, fluorenone, azo-compound, phenoxazine, phenothiazine, alloxazine, isoalloxazine, and / or bipyridinium.PATENTAttorney Docket No. 51198-070W0213. The method of any one of claim 1-11, wherein the mediator comprises at least one of vanadium or chromium.

14. The method of any one of claims 1-12, wherein the mediator comprises a compound of formula (I):HOOC(I), or a salt thereof.

15. The method of any one of claims 1-12, wherein the mediator comprises a compound of formula (II):or a salt thereof.

16. The method of any one of claims 1-12, wherein the mediator comprises a compound of formula (III):OO (III), or a salt thereof.

17. The method of any one of claims 1 -16, wherein the unsaturated compound comprises at least one group selected from an alkene, an alkyne, a carbonyl, or a reducible nitrogen.

18. The method of any one of claims 1-17, wherein contacting the aqueous phase, the nonaqueous phase, and the solid phase occurs in a reactor.

19. The method of any one of claims 1-18, further comprising:reducing a mediator to form the mediator in the reduced state in an electrochemical cell.

20. The method of any one of claims 1-19, further comprising:separating the solid phase from the aqueous phase and the nonaqueous phase.

21. The method of any one of claims 1 -20, further comprising:PATENTAttorney Docket No. 51198-070W02transferring the aqueous phase to the electrochemical cell.

22. The method of any one of claims 1 -21 , wherein the hydrogenated product is a fully hydrogenated product or a partially hydrogenated product.

23. A method, comprising:contacting a solid phase including catalyst with:a nonaqueous phase including a reactant, comprising an unsaturated compound; andan aqueous phase comprising a mediator in a reduced state; andallowing a hydrogen species to transfer from the aqueous phase to the reactant via the catalyst to form a hydrogenated product.

24. The method of claim 23, wherein the unsaturated compound comprises at least one group selected from an alkene, an alkyne, a carbonyl, or a reducible nitrogen.

25. The method of claim 23 or 24, further comprising:prior to the contacting, reducing a mediator to form the mediator in the reduced state in an electrochemical cell.

26. The method of claim 25, wherein the electrochemical cell includes a cathode and a cathode region configured to receive an alkaline aqueous solution including the mediator.

27. The method of claim 26, wherein the electrochemical cell comprises a membrane configured to separate an anode from the cathode, wherein the membrane is configured to prevent oxidation of the mediator in the reduced state.

28. The method of claim 27, wherein the membrane is a size-exclusion membrane or a protonexchange membrane.

29. The method of any one of claims 25-28, further comprising:transporting the aqueous phase comprising the mediator in the reduced state to a reactor fluidically coupled to the electrochemical cell, wherein the contacting occurs in the reactor.

30. The method of any one of claim 23-29, wherein the contacting includes agitating the aqueous phase, the nonaqueous phase, and the solid phase such that at least a portion of the solid phase is at an interface between the aqueous phase and the nonaqueous phase.

31. The method of any one of claims 23-30, wherein the mediator includes a phenazine, quinoxaline, anthraquinone, naphthoquinone, benzoquinone, fluorenone, azo-compound, phenoxazine, phenothiazine, alloxazine, isoalloxazine, bipyridinium vanadium, and / or chromium.PATENTAttorney Docket No. 51198-070W0232. The method of any one of claims 23-31 , wherein at least a portion of the solid phase localizes at an interface between the aqueous phase and the nonaqueous phase.

33. The method of any one of claims 23-32, wherein the mediator has a potential, under reaction conditions, that is more negative than an underpotential deposition threshold (VuPd) for deposition of the hydrogen species on the catalyst.

34. The method of any one of claims 23-33, wherein the hydrogenated product is a fully hydrogenated product or a partially hydrogenated product.

35. A system, comprising:an electrochemical cell comprising a mediator in an aqueous phase; anda reactor comprising a nonaqueous phase comprising an unsaturated compound and a solid phase comprising a catalyst and being fluidically couplable to the electrochemical cell, wherein the reactor is configured to receive at least a portion of the aqueous phase to contact the mediator in the reduced state with the catalyst to form a hydrogenated product in the nonaqueous phase.

36. The system of claim 35, wherein the unsaturated compound comprises at least one group selected from an alkene, an alkyne, a carbonyl, or a reducible nitrogen.

37. The system of claim 35 or 36, further comprising:an agitator configured to agitate the aqueous phase, the nonaqueous phase, and the solid phase.

38. The system of claim 37, further comprising:a first separator fluidically couplable to the reactor, the first separator configured to separate the solid phase from the aqueous and nonaqueous phases to form a second mixture including the aqueous phase and the nonaqueous phase.

39. The system of claim 38, further comprising:a second separator fluidically couplable to the first separator, the second separator configured to receive the second mixture and separate the aqueous phase from the nonaqueous phase.

40. The system of claim 39, further comprising:a recirculation assembly fluidically coupled to at least one of the electrochemical cell, the reactor, the first separator, or the second separator, the recirculation assembly configured to:transfer at least a portion of the separated solid phase from the first separator to the reactor; or transfer at least a portion of the separated aqueous phase to the electrochemical cell.

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