Carboxylation of a substrate using carbon dioxide photocatalysis

Abstract

A photo-driven method for producing carboxylic acids from various substrates, including alkanes, alkenes, alkynes, esters, ethers, and amines, using a photocatalyst and carbon dioxide. In preferred embodiments, the method of the present invention offers the ability to use lower-cost feedstocks, produce carboxylic acids at lower temperatures than existing methods, and convert carbon dioxide into value-added carboxylic acids.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority to U.S. Provisional Application No. 63 / 537,912, filed on 12 September 2023, which is incorporated herein by reference as if it were described in its entirety.

[0002] (Description of research or development supported by the federal government) This invention was made with federal government support under authorization number 2151548, granted by the National Science Foundation. The federal government has certain rights to this invention. [Background technology]

[0003] Carboxylic acids form important classes of compounds and are used directly, for example, in the preservation of animal feed (including hay, silage, and grains) and in human food (e.g., baked foods and cheese). Carboxylic acid esters are used as solvents for a variety of applications, particularly as food and flavor additives where desirable odor and flavor characteristics are important. Furthermore, butyrate esters are used, for example, to produce cellulose acetate butyrate (CAB), which is used in a wide variety of tools, paints, and coatings and is more resistant to degradation than cellulose acetate, and the potassium salt of isobutyrate is effective as a dissolution accelerator in the caustic extraction of mercaptans from sour petroleum stocks. However, the production of carboxylic acids using fossil fuel-derived methods can release carbon dioxide emissions, which contribute to global warming, ecological damage, and risks to human health. As these potential impacts are assessed, there is a growing demand for more environmentally friendly methods of producing chemical products. Industrially, carbon chain length C n The production of aliphatic carboxylic acids containing carbon monoxide is typically carried out by C n-1 C n-1 via the hydrocarboxylation of alkenes (e.g., U.S. Patent No. 4,619,790), or C nThis is achieved through the oxidation of aldehydes (e.g., Canadian Patent No. 1081254). All of these methods require petrochemical raw materials, metal catalysts, and high temperatures.

[0004] The present invention relates to a photo-driven method using a photocatalyst and carbon dioxide, which in a preferred embodiment preferably provides the ability to use lower-cost raw materials and / or preferably the ability to produce carboxylic acids at lower temperatures than existing methods and / or preferably the ability to convert carbon dioxide into value-added carboxylic acids.

[0005] For clarity, the terms “invention,” “the invention,” and “the present invention” used herein refer only to the specific embodiments and / or aspects of the invention described immediately prior to this. These do not broadly limit in any sense the overall contribution of the inventors to the art described herein, nor do they generally or specifically limit the individual advances in the art described herein. [Overview of the project] [Means for solving the problem]

[0006] The inventors have discovered a photo-driven method for producing carboxylic acids from various substrates, including alkanes, alkenes, alkynes, ethers, esters, and amines, using a photocatalyst and carbon dioxide. In preferred embodiments, the method of the present invention offers the ability to produce carboxylic acids using lower-cost feedstocks and at lower temperatures than existing methods, as well as the ability to convert carbon dioxide into value-added carboxylic acids. [Modes for carrying out the invention]

[0007] The present invention relates to a method for producing a carboxylic acid by directly carboxylating a substrate selected from one or more of alkanes, alkenes, alkynes, ethers, esters, and amines.

[0008] In preferred embodiments, the method of the present invention comprises a liquid-phase, gas-phase, or mixed liquid-gas-phase system for reacting one or more substrates with carbon dioxide to produce one or more carboxylic acids. Both liquid and gaseous substrates can be converted to carboxylic acids using the method of the present invention.

[0009] In one embodiment, the substrate feedstock is introduced into a reactor containing a solvent and / or directly liquefied, and the carbon dioxide feedstock is introduced into the same reactor. In certain embodiments, the method utilizes at least one photocatalyst and at least one cocatalyst. In certain embodiments, ligands and / or additives may be added to the system. The reaction mixture containing the desired reactants, catalyst, and other components, etc., is irradiated with a light source, which activates the photocatalyst and initiates the reaction to produce a carboxylic acid.

[0010] In a preferred embodiment, the method generates a desired carboxylic acid product using one or more substrates, carbon dioxide, a photocatalyst, a transition metal cocatalyst, a ligand, and a solvent in the presence of light.

[0011] In a preferred embodiment, the method involves reacting propane with carbon dioxide to produce isobutyric acid and butyric acid. In a preferred embodiment, the method involves reacting ethane with carbon dioxide to produce propionic acid.

[0012] In a preferred embodiment, the method involves reacting dimethyl ether with carbon dioxide to produce methoxyacetic acid. In a preferred embodiment, the method involves reacting diethyl ether with carbon dioxide to produce 2-ethoxypropanoic acid. In a preferred embodiment, the method involves reacting ethyl acetate with carbon dioxide to produce 2-acetoxypropionic acid.

[0013] Descriptions of methods for producing carboxylic acids, and specific oxidation reactions, catalysts, reaction conditions, etc., that have aspects useful in this specification, can be found, for example, in U.S. Patent No. 4,619,790, Canadian Patent No. 1081254, Japanese Patent Publication No. 2002-515472, U.S. Patent No. 9,085,827, Japanese Patent No. 6404125, U.S. Patent No. 8,592,633, Ishida et al., "A Light / Ketone / Copper System for Carboxylation of Allylic CH Bonds of Alkenes with CO2," Chemistry, A European Journal, Vol. 22, No. 19, May 2016, and Ishida et al., "Carboxylation of Benzylic and Aliphatic CH Bonds with CO2 Induced by CO2 These are described in "Light / Ketone / Nickel)," J.Am.Chem.Soc. 2019, Vol. 141, No. 50, pp. 19611–19615, and are incorporated herein by reference as containing their full texts.

[0014] In this specification, articles such as "a," "an," and "the" placed before an element or component of the present invention shall not be limited in meaning with respect to the number (i.e., frequency of occurrence) of the element or component. Accordingly, "a," "an," and "the" should be interpreted as meaning one or more, and the singular form of an element or component shall also be considered to include the plural form unless its number clearly means singular.

[0015] As used herein, “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and their variations are intended as open-ended transitional phrases, terms, or words that do not preclude the possibility of additional features, components, actions, steps, groups, structures, etc. As used herein, including within a claim, the term “comprising” is intended to include embodiments encompassed by the terms “consisting essentially of” and “consisting of.” Similarly, the term “consisting essentially of” is intended to include embodiments encompassed by the term “consisting of.”

[0016] Where used herein, if a quantity, concentration, or other numerical value or parameter is described as a range or a list of values, these shall be interpreted as including endpoints, and all ranges formed by any combination of upper and lower limits shall be specifically disclosed, and further, whether the range, all integers, and fractions are disclosed individually or not, all integers and fractions within that range shall be specifically disclosed. For example, both the range "3 to 10" and the enumeration of values ​​"3, 6, 7, 9, 10" specifically disclose and encompass not only the individual values ​​3, 4.7, 8.3, and 10, but also ranges such as 5 to 7 and 6 to 9. The numerical limits described include appropriate precision based on the number of significant figures used. For example, "up to 5.0" is interpreted as setting a lower absolute upper limit than "up to 5".

[0017] Where used herein, when naming a substance that may exist in multiple enantiomer forms, references to substance names without enantiomer designations such as (d) or (l) shall, unless otherwise specified, refer to the collective term for the substance including (d) type, (l) type, and racemic mixtures (e.g., d,l). Similarly, general references to compounds that may exist as two or more polymorphs shall be understood to refer to the group of substances consisting of the individual polymorph species and any combination or mixture thereof.

[0018] Any published papers, references, brochures, documents, etc., including patents and published patent applications, identified herein shall be incorporated herein by reference as if they were contained herein.

[0019] Without being constrained or limited by any theory, the inventors assume that the mechanism of the method of the present invention involves exciting a photocatalyst to generate an excited radical, which then activates a CH bond in the substrate (e.g., a CH bond on an sp3 hybridized carbon atom) to form an alkyl radical. Subsequently, this alkyl radical interacts with a cocatalyst to form a metal alkyl intermediate, which reacts with carbon dioxide to form a metal carboxylate. Then, the carboxylic acid product is liberated by proton and electron transfer, regenerating both the catalyst and cocatalyst, and restarting the cycle.

[0020] In some embodiments thereof, the method of the present invention provides at least two major advantages over other methods. First, the method of the present invention uses carbon dioxide as a direct chemical feedstock. As a direct chemical feedstock, carbon dioxide is low-cost and environmentally friendly compared with other feedstocks used for producing carboxylic acids, and it is also a greenhouse gas that contributes to climate change. Accordingly, the method of the present invention provides a direct approach for functionalizing carbon dioxide into value-added products. Second, the method of the present invention uses light to drive the reaction via catalysis, and generally does not require the same amount of heat as other processes to proceed. This enables, for example, electrification of the process, and utilization of renewable energy sources (such as solar energy, wind energy, etc.) not only eliminates carbon dioxide emissions from product synthesis, but also enables utilization of carbon dioxide in the synthesis of the present invention. Of course, the elimination of substantial heating requirements also allows significant reduction of the industrial production cost of carboxylic acids.

[0021] In a preferred embodiment, the method of the present invention is a liquid phase, gas phase, or mixed liquid / gas phase oxidation method. For example, one or more substrates in a liquid phase and / or gas phase are reacted with carbon dioxide to produce a carboxylic acid.

[0022] The method for bringing the substrate into contact with carbon dioxide in the presence of, for example, a catalyst is not particularly limited. In one embodiment, the substrate feedstock is introduced into a reactor containing a solvent. In another embodiment, the substrate feedstock is fed to the reactor in a liquefied form. In another embodiment, the substrate feedstock is liquefied in the reactor in the absence or presence of a solvent. In another embodiment, a gas phase reaction is used in which both the substrate and carbon dioxide are in a gaseous form during the reaction.

[0023] The alkane substrate used in the method of the present invention is not particularly limited. For example, the alkane may be linear or branched, symmetric or asymmetric, cyclic or acyclic. Preferable carbon number ranges include C1 to C35. A mixture of two or more types may be used. In certain embodiments, the alkane is a C1 to C26 alkane, including C2, C3, C4, C5 and C6 alkanes, with ethane and propane being particularly noted. In a preferred embodiment, the alkane is of general formula C n H 2n+2 which is an acyclic branched or unbranched hydrocarbon, wherein n is 1 to 26, preferably 2 to 10, more preferably 2 to 5. Ethane, propane, butane, isobutane, pentane, isopentane, and cyclohexane are particularly preferred. In another preferred embodiment, the alkane is a C3 to C26, preferably C5, C6, C7, or C8 monocyclic or polycyclic alkane.

[0024] The source of the alkane(s) is not limited. For example, propane and ethane can be supplied from natural gas (propane and ethane are generally referred to as NGL or natural gas liquids). Renewable sources, bio-based feedstocks and the like can be used.

[0025] The alkene substrate used in the method of the present invention is not particularly limited. For example, the alkene may be linear or branched, symmetric or asymmetric, cyclic or acyclic, aromatic or non-aromatic. Preferable carbon number ranges include C2 to C35. A mixture of two or more types may be used. In certain embodiments, the alkene is a C2 to C26 alkene, including C2, C3, C4, C5 and C6 alkenes, with ethene and propene being particularly noted. In a preferred embodiment, the alkene is of general formula C n H 2nIt is an acyclic branched or unbranched hydrocarbon having, wherein in the formula, n is 1 to 26, preferably 2 to 10, more preferably 2 to 5. Ethene, propene, butene, isobutene, pentene, and isopentene are particularly preferred. In another preferred embodiment, the alkene is a C3 to C26, preferably C5, C6, C7, or C8 monocyclic or polycyclic alkene. The source of the alkene(s) is not limited. Renewable sources, bio-based feedstocks and the like can be used.

[0026] The alkyne substrate used in the method of the present invention is not particularly limited. For example, the alkyne may be linear or branched, symmetric or asymmetric, cyclic or acyclic. Preferred carbon numbers include C2 to C35. A mixture of two or more kinds may be used. In a specific embodiment, the alkyne is a C2 to C26 alkyne, including C2, C3, C4, C5 and C6 alkynes, with ethyne and propyne being particularly notable. In a preferred embodiment, the alkyne is of the general formula C n H 2n-2 It is an acyclic branched or unbranched hydrocarbon having, wherein in the formula, n is 1 to 26, preferably 2 to 10, more preferably 2 to 5. Ethyne, propyne, butyne, isobutyne, pentyne, and isopentyne are particularly preferred. In another preferred embodiment, the alkyne is a C3 to C26, preferably C5, C6, C7, or C8 monocyclic or polycyclic alkyne. The source of the alkyne(s) is not limited. Renewable sources, bio-based feedstocks and the like can be used.

[0027] The ether substrate used in the method of the present invention is not particularly limited. For example, the ether may be linear or branched, symmetric or asymmetric, cyclic or acyclic, aromatic or non-aromatic. Preferred carbon number is C2 to C35. A mixture of two or more may be used. In certain embodiments, the ether is a C2 to C26 ether, including C2, C3, C4, C5 and C6 ethers, with particular interest being dimethyl ether and diethyl ether. In preferred embodiments, the ether is acyclic, branched or unbranched. Dimethyl ether, diethyl ether, anisole, tetrahydrofuran, furan and dioxane are particularly preferred. In another preferred embodiment, the ether is a monocyclic or polycyclic ether of C3 to C26, preferably C5, C6, C7, or C8. The source of ether(s) is not limited. Renewable sources, bio-based raw materials, etc., can be used.

[0028] The ester substrate used in the method of the present invention is not particularly limited. For example, the ester may be linear or branched, symmetric or asymmetric, cyclic or acyclic, aromatic or non-aromatic. Preferred carbon number is C3 to C35. A mixture of two or more may be used. In certain embodiments, the ester is a C3 to C26 ether, including C3, C4, C5, and C6 esters, with methyl acetate, ethyl acetate, ethyl propionate, and isopropyl butyrate being particularly noteworthy. In preferred embodiments, the ester is acyclic, branched or unbranched. Methyl acetate, ethyl acetate, ethyl propionate, isopropyl butyrate, ethyl benzoate, and ethyl lactate are particularly preferred. In another preferred embodiment, the ester is a monocyclic or polycyclic ester of C3 to C26, preferably C5, C6, C7, or C8. The source of ester(s) is not limited. Renewable sources, bio-based raw materials, etc., can be used.

[0029] The amine substrate used in the method of the present invention is not particularly limited. For example, the amine may be a primary, secondary, or tertiary amine that is linear or branched, symmetric or asymmetric, cyclic or acyclic, aromatic or non-aromatic. Preferred carbon number ranges include C3 to C35. Mixtures of two or more amines may be used. In certain embodiments, the amine is a C3 to C26 amine, including C3, C4, C5, and C6 amines, with particular interest being methylamine, ethylamine, and isopropylamine. In preferred embodiments, the amine is acyclic, branched or unbranched. Ammonia, methylamine, and ethylamine are particularly preferred. In another preferred embodiment, the amine is a monocyclic or polycyclic amine of C3 to C26, preferably C5, C6, C7, or C8. The source of amine(s) is not limited. Renewable sources, bio-based raw materials, etc., can be used.

[0030] Useful substrates as used herein include compounds having two or more identical or distinct functional groups that constitute alkanes, alkenes, alkynes, ethers, esters, and amines. Examples include ethyl methacrylate, acrylamide, and palmitic acid. The source of such substrates is not limited. Renewable sources, bio-based feedstocks, etc., can be used. In either case, the preferred substrate group includes at least one sp3 hybridized carbon.

[0031] The carbon dioxide used in the method of the present invention is not particularly limited. It can be used in any physical form, including solid, liquid, gas, and mixtures thereof. The carbon dioxide used in the method of the present invention may be added to or present in the reaction zone in a mixture with one or more other gases. Pure carbon dioxide (meaning carbon dioxide not mixed with other gases) and carbon dioxide mixed with non-reactive gases such as nitrogen and noble gases (helium, neon, argon, krypton, xenon, radon, etc.) are preferred. If a mixture is used, the mixture preferably contains at least 1% carbon dioxide by volume, and more preferably 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50% or more. The source of carbon dioxide is not limited. Various carbon capture sources can be used, such as point sources (e.g., from furnace flues or chimneys, or from cement or other industrial plants). Direct atmospheric capture (DAC) from the atmosphere can also be used.

[0032] The photocatalyst used in the method of the present invention is a carbon-hydrogen (CH) photoactivated catalyst (photocatalyst) and is not particularly limited as long as it photocatalyzes the direct carboxylation of at least one of alkanes, alkenes, alkynes, ethers, esters, and amines. A mixture of two or more carbon-hydrogen (CH) photoactivated catalysts may also be used. In a preferred embodiment, the photocatalyst is a benzophenone such as benzophenone itself, 4,4′-di-tert-butylbenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-difluorobenzophenone, 4,4′-bis(dimethylamino)benzophenone, 4,4′-dihydroxybenzophenone, 4,4′-bisphenylbenzophenone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2-trifluoromethylbenzophenone, 3-fluorobenzophenone, 4-trifluoromethylbenzophenone, 4,4′-diaminobenzophenone, 4,4′-dibromobenzophenone, 4,4′-dicyanobenzophenone, 4-nitrobenzophenone, 2,4-difluorobenzophenone, decafluorobenzophenone, benzophenone imine, 4-tert-butylbenzophenone, or 2,2′,4,4′-tetramethylbenzophenone.

[0033] The light used with the photocatalyst is preferably light having a wavelength range of 250 to 550 nm, more preferably 300 to 500 nm, most preferably 340 to 450 nm, for example, 365 nm. In general, the light can be used in any way, such as by varying the exposure time, and can be used at various irradiation doses, wavelengths, and illuminance levels as determined by those skilled in the art, taking into account the specific catalyst and apparatus used, in view of this disclosure. In a preferred embodiment, the method of the present invention can be carried out while irradiating the reaction zone containing the photocatalyst with light. Multiple wavelengths may be used.

[0034] The cocatalyst is any reagent used in the method of the present invention, but is preferably used. The cocatalyst is not particularly limited as long as it assists the photocatalytic action in which the substrate is directly carboxylated to produce a carboxylic acid, together with the photocatalyst. A mixture of two or more cocatalysts may be used. Transition metal cocatalysts are preferred. Examples of useful cocatalysts include nickel, cobalt, and palladium compounds or complexes, such as nickel(II) nitrate hexahydrate, nickel(II) bis(acetylacetonate), nickel(II) bis(acetylacetonate)-4,4′-dimethoxy-2,2′-bipyridine, nickel(II) bis(2,2,6,6-tetramethyl-3,5-heptanedione), nickel(II) bis(dimethylglyoximate), nickel(II) bis(dimethylglyoximate difluoroborate), nickel(II) bis(diphenylglyoximate), nickel(II) salen, nickel(II) bis(di-2-pyridinylmethanone), tris(trans-1,2-bis(4-tert-butylphenyl)ethene)nickel(O), cobalt(II) bis(acetylacetonate), and bis(dibenzylideneacetone)palladium(O). Mixtures may also be used.

[0035] The ligand is any reagent used in the method of the present invention, but is preferably used. It is not particularly limited. A mixture may be used. In preferred embodiments, aromatic amines such as pyridine, bipyridine, and derivatives of phenanthroline derivatives are used. Examples include 2-picolylamine, OMebpy (4,4′-dimethoxy-2,2′-bipyridine), OMephen (4,7-dimethoxy-1,10-phenanthroline), and neocuproine (2,9-dimethyl-1,10-phenanthroline).

[0036] The additives are any reagents used in the method of the present invention, but it is preferable to use at least one. These additives are not particularly limited. A mixture may be used. Preferred additives include cesium salts such as cesium fluoride, cesium hydroxide, and cesium pivalate, and polycyclic aromatic hydrocarbons such as anthracene.

[0037] The solvent is any component of the method of the present invention, but is preferably used. It is not particularly limited. Preferably, the solvent is non-reactive. A mixture may be used. In preferred embodiments, one or more of the following are used: propylene carbonate, tert-butanol, acetonitrile, dimethyl carbonate, dimethyl sulfoxide, dimethylformamide, dimethoxyethane, hexamethylphosphoramide, tetrahydrofuran, dimethylacetamide, benzonitrile, pyridine, ethyl acetate, acetone, ethylene glycol, and nitromethane. Acetone, methyl acetate, and dimethyl carbonate are preferred. Oxygenated solvents (ketones, carbonates, esters, alcohols, etc.) are preferred when using an alkane substrate.

[0038] A non-limiting list of preferred photocatalysts, cocatalysts, ligands, additives, and solvents useful in this specification, along with their CAS numbers, is provided below. Each photocatalyst, cocatalyst, ligand, additive, and solvent described herein may be used in combination with any other photocatalyst, cocatalyst, ligand, additive, and solvent described herein.

[0039] PrC Propylene Carbonate 108-32-7 t-BuOH tert-butanol 75-65-0 ACN Acetonitrile 75-05-8 DMC Dimethyl Carbonate 616-38-6 DMSO (Dimethyl Sulfoxide) 67-68-5 DMF Dimethylformamide 68-12-2 DME Dimethoxyethane 110-71-4 HMPA Hexamethylphosphoramide 680-31-9 THF Tetrahydrofuran 109-99-9 DMAc Dimethylacetamide 127-19-5 PhCN Benzonitrile 100-47-0 Py Pyridine 110-86-1 EtAc (ethyl acetate) 141-78-6 Act Acetone 67-64-1 EtGy Ethylene Glycol 107-21-1 NO2Me Nitromethane 75-52-5

[0040] TMAH 2,3,6,7-Tetramethoxyanthracene-9(10H)-one 128080-46-6 TMAO 9,10-Diethyl-2,3,6,7-Tetramethoxyanthracene 5629-55-0 BP Benzophenone 119-61-9 tBBP 4,4′-di-tert-butylbenzophenone 15796-82-4 OMeBP 4,4′-Dimethoxybenzophenone 90-96-0 DFBP 4,4′-Difluorobenzophenone 345-92-6 ANQ Anthraquinone 84-65-1 DQ Jurokinon 527-17-3 CA Chloranil 118-75-2 10-Methylacridine-9(10H)-one 719-54-0 3,3′,4,4′,5-Pentamethoxybenzophenone 22699-97-4 Benzophenone imine 1013-88-3 4-tert-butylbenzophenone 22679-54-5 4,4′-Dimethylbenzophenone 611-97-2 2,2′,4,4′-Tetramethylbenzophenone 3478-88-4 Xanthon 90-47-1 Di-p-tolylmethanol 885-77-8 (2-Me-benzoyl)benzoate 606-28-0 4,4′-(NMe2)2-BP 4,4′-bis(dimethylamino)benzophenone 90-94-8 4,4′-(OH)2-BP 4,4′-Dihydroxybenzophenone 611-99-4 4,4′-Ph2-BP 4,4′-Bisphenylbenzophenone 3478-90-8 Thioxanthone 492-22-8 3,6-(tBu)2-acridone 3,6-di-tert-butylacridin-9(10H)-one 1810004-91-1 2-Me-BP 2-methylbenzophenone 131-58-8 3-Me-BP 3-methylbenzophenone 643-65-2 4-Me-BP 4-methylbenzophenone 134-84-9 2-CF3-BP 2-trifluoromethylbenzophenone 727-99-1 3-F-BP 3-fluorobenzophenone 345-69-7 4-CF3-BP 4-trifluoromethylbenzophenone 728-86-9 kaleidophenone 1,3,5-tribenzoylbenzene 25871-69-6 2-aza-BP 2-benzoylpyridine 91-02-1 3-aza-BP 3-benzoylpyridine 5424-19-1 Antron 90-44-8 DPSO Diphenyl sulfoxide 945-51-7 Fluorenone 486-25-9 4,4′-(NH2)2-BP 4,4′-diaminobenzophenone 611-98-3 DPS Diphenylsulfone 127-63-9 Kanfaquinon 10373-78-1 4-B(OH)2-BP (4-benzoylphenyl)boronic acid 268218-94-6 4CzIPN 1,2,3,5-Tetrakis(carbazole-9-yl)-4,6-dicyanobenzene 1416881-52-1 4,4′-Br2-BP 4,4-dibromobenzophenone 3988-03-2 4,4′-(CN)2-BP 4,4′-dicyanobenzophenone 32446-66-5 4-NO2-BP 4-nitrobenzophenone 1144-74-7 2,4′-F2-BP 2,4-difluorobenzophenone 342-25-6 decaFBP Decafluorobenzophenone 853-39-4 4,4′-F2-PhCOPhCOPh 1,3-bis(4-fluorobenzoyl)benzene 108464-88-6 2,2,2-Ph3-acetophenone 2,2,2-triphenylacetophenone 466-37-5 Py-BP 2,2′-Dipyridylketone 19437-26-4

[0041] bpy 2,2′-bipyridine 366-18-7 OMebpy 4,4′-dimethoxy-2,2′-bipyridine 17217-57-1 CF3bpy 4,4′-Bis(trifluoromethyl)-2,2′-Bipyridine 142946-79-0 OMephen 4,7-dimethoxy-1,10-phenanthroline 92149-07-0 tBubpy 4,4′-di-tert-butyl-2,2′-bipyridine 72914-19-3 tpy 2,6-di(2-pyridyl)pyridin-α,α′,α″-tripyridyl 1148-79-4 mephen Neocuproine 484-11-7 Neocuproine 2,9-dimethyl-1,10-phenanthroline 484-11-7 2-Picolylamine 3731-51-9 CataCXiumA 321921-71-5 BINAP (±)-2,2′-bis(diphenylphosphin)-1,1′-binaphthalene 98327-87-8 DPPF 1,1′-Bis(diphenylphosphino)ferrocene 12150-46-8 Mg(Pc) Magnesium Phthalocyanine 1661-03-6 Mg(Tpp) Mg(II) mesotetraphenylporfin 14640-21-2 Mg(OEP) Magnesium Octaethylporphyrin 20910-35-4 P(tBu)3 Tri-t-butylphosphine 13716-12-6 Glycine 56-40-6 TEA Triethylamine 121-44-8 TEOA Triethanolamine 102-71-6 DIPEA Diisopropylethylamine 7087-68-5 DBU 1,8-Diazabicyclo[5.4.0]Undeca-7-en 6674-22-2 tBuOK Potassium t-butoxide 865-47-4 N(Et)4Cl Tetraethylammonium Chloride 56-34-8 PPh3O Triphenylphosphine oxide 791-28-6

[0042] Ni(NO3)2-6H2O Nickel nitrate hexahydrate 13478-00-7 Ni(acac)2 Nickel Acetyl Acetonate 3264-82-2 Ni(acac)2OMebpy Nickel bis(acetylacetone)-4,4′-dimethoxybipyridine 803687-13-0 Ni(dmgH)2 Nickel(II) Bis(dimethylglyoxymate) 13478-93-8 Ni(dmgBF2)2 Nickel(II) bis(dimethylglyoxymate difluoroborate) 35200-43-2 Ni(dpgH)2 Nickel(II) Bis(Diphenylglyoxymate) 14286-61-4 Ni(salen) Nickel(II) Salen 14167-20-5 Ni(py-BP)2 Nickel(II) bis(di-2-pyridinylmethanone) 5629-55-0 Ni(tmhd)2 Nickel(II) bis(2,2,6,6-tetramethyl-3,5-heptanedionic acid) 14481-08-4 Ni(tBu-stb)3 Tris(trans-1,2-bis(4-tert-butylphenyl)ethene) Nickel(0) 2468315-70-8 Pd(dba)2bis(dibenzylideneacetone)palladium(0) 32005-36-0

[0043] In one embodiment, the method of the present invention can be seen as using a catalyst composition comprising at least one photocatalyst, optionally at least one cocatalyst, optionally at least one ligand, and optionally at least one additive.

[0044] When a solvent is used, the amount of substrate reactants present in the reaction zone is not limited, but preferably at least 1 volume% of substrate / solvent, more preferably 5 to 95% of substrate / solvent by volume (including 6, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, and 90% of substrate / solvent by volume).

[0045] The amount of photocatalyst used in the method of the present invention is not limited. Based on the total volume of the substrate and any solvent, the catalyst can be used in amounts ranging from 0.0001 to 500 mM (including 0.005, 0.01, 0.05, 0.1, 0.5, 1, 3, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, and 400 mM) for each catalyst used.

[0046] The amount of any co-catalyst used in the method of the present invention is not limited. Based on the total volume of the substrate and any solvent, the co-catalyst can be used in amounts ranging from 0.0001 to 500 mM (including 0.005, 0.01, 0.05, 0.1, 0.5, 1, 3, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, and 400 mM) for each co-catalyst used.

[0047] The amount of any ligand used in the method of the present invention is not limited. Based on the total volume of the substrate and any solvent, the additive may be used in amounts ranging from 0.0001 to 500 mM (including 0.005, 0.01, 0.05, 0.1, 0.5, 1, 3, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, and 400 mM) for each ligand used.

[0048] The amount of any additive used in the method of the present invention is not limited. Based on the total volume of the substrate and any solvent, the additive may be used in amounts ranging from 0.0001 to 500 mM (including 0.005, 0.01, 0.05, 0.1, 0.5, 1, 3, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, and 400 mM) for each additive used.

[0049] The catalyst composition used in the method of the present invention can generally be prepared according to procedures commonly used in the art, and may also be prepared separately before being introduced into the reaction zone. Alternatively, each component of the catalyst composition can be added to the reaction zone individually or in any combination.

[0050] The method of the present invention can be achieved by any method of coexisting the substrate, carbon dioxide, and catalyst composition in the reaction zone under conditions (time, temperature, pressure, etc.) sufficient to produce the carboxylation product. Examples include batch, fed-batch, and continuous processes. In a preferred embodiment, a fed-batch method is used, for example, by keeping the pressure of the carbon dioxide-containing gas relatively constant throughout the reaction.

[0051] In a preferred embodiment, the method of the present invention is not carried out in the presence of a sacrificial base. In a preferred embodiment, the method of the present invention is not carried out in the presence of a sacrificial acid.

[0052] In a preferred embodiment, the method of the present invention is carried out while irradiating the reaction zone with light, preferably light having a wavelength range of 300-400 nm or 340-370 nm, including 250-550 nm, for example, 365 nm. Two or more wavelengths can be used. In general, the light can be used in any way, for example, by varying the exposure time, and can be used at various irradiation doses, wavelengths, and illuminance levels as determined by those skilled in the art, taking into account the specific catalyst composition and apparatus used in view of this disclosure. If necessary, multiple wavelengths of light can be used in combination and / or sequentially.

[0053] In certain embodiments, the method of the present invention can be carried out under pressures of 1 to 200 bar (gauge), including 2, 3, 4, 5, 6, 7, 8, 10, 15, 20, 30, 40, 50, 60, 70, 80, and 90 bar, and at temperatures below room temperature (25°C) to above room temperature, such as -20, -10, 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 140, 180, 220, 260, and 300°C. In certain embodiments, the preferred temperature is 0 to 50°C.

[0054] In certain embodiments, the method of the present invention can be carried out in a time of 15 minutes to 40 hours (batch and fed-batch), and good results can be obtained in about 1, 2, 3, 4, and 5 to 25 hours (including 8, 16, and 24 hours). Generally, the greater the amount of substrate present, the longer the reaction takes.

[0055] In a preferred embodiment, the reaction of the present invention is carried out under fed-batch conditions in which carbon dioxide and the reaction substrate are continuously supplied, particularly when they are in gaseous form, and a desired pressure is maintained. For example, the substrate, an arbitrary solvent, and the catalyst composition are placed in a container, the air in the container is purged, and replaced with carbon dioxide. The system is then pressurized to a desired pressure with a gas, for example, ethane, propane, or dimethyl ether, and the container is irradiated with, for example, a 250-450 nm LED and a 365 nm LED, while maintaining the temperature. After a given reaction time (e.g., 16 hours), the light is turned off, and the reaction mixture is processed and analyzed, etc.

[0056] In one embodiment of this specification, light alkanes such as ethane and propane are used as substrates. In one embodiment of this specification, no base (e.g., t-BuOk) is used. In one embodiment of this specification, light alkanes such as ethane and propane are used as substrates, and no base (e.g., t-BuOk) is used. In one embodiment of this specification, dimethyl ether is used as the substrate.

[0057] The contact step of the present invention can be carried out in any way and on any scale, including from laboratory-scale experiments to full-scale commercial operation. The method can be operated in any way, including batch, fed-batch, continuous, and semi-continuous modes. The contact step can be carried out in any of the various ways. The order of addition of the reactants (substrate, components of the catalyst composition, carbon dioxide, any solvent, etc.) is not particularly important. For example, the materials can be added individually, or two or more materials can be combined or mixed before being combined or mixed with other materials.

[0058] The present invention can be carried out using conventional liquid-phase and gas-phase oxidation reactors known in the art. Examples include vessels that may have one or more mechanical stirrers, and various bubble column reactors as described in U.S. Patent No. 7,692,036. It is also known that such reactors and oxidation reactions can be designed, operated, and controlled to suit the oxidation conditions employed (e.g., temperature, pressure, volume of liquid and gas, and, where applicable, the corrosiveness of the liquid and gas phases). See, for example, U.S. Patents No. 7,692,036 and No. 6,137,001.

[0059] In a preferred embodiment, the method achieves substrate conversion rates (i.e., carboxylation) of at least 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, and 98%. In preferred embodiments, the method provides selectivity for carboxylic acid formation of at least 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, and 99%. Preferably, the selectivity for all by-products is less than 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, and 1%.

[0060] In certain preferred embodiments, the method of the present invention using propane provides isobutyric acid and butyric acid in a ratio ranging from 4:1 to 28:1, with a yield of 167.9 mM for isobutyric acid and 16.5 mM for butyric acid. When ethane is used, the yield of the product propionic acid is 33.4 mM. [Examples]

[0061] Tables 1, 2, and 3 summarize numerous non-limiting examples.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] General procedures using propane and ethane as substrates: In a further exemplary embodiment, 13.09 mg (0.06 mmol) of 4,4′-difluorobenzophenone, 2.55 mg (0.006 mmol) of Ni(tmhd)2, and 1.44 mg (0.006 mmol) of OMephen are added to an Ace Glass pressure tube (part number: 8648-42). A small stirring blade is placed in the same flask, followed by the addition of 3 mL of acetone. After purging the gas line through a gas manifold attached to a Schlenklein, the tube is attached to the gas manifold. 20 psig of propane is packed into the reaction tube, then the pressure is released, and this cycle is repeated five times. 99 psig of propane is introduced and allowed to dissolve in the solvent for approximately 2 minutes. CO2 is then added to bring the total pressure to 132 psig, and then additional gases are supplied in a pre-mixed ratio while maintaining the connection to the gas buffer and shutting off the system from both gases. Subsequently, the reaction system is actively cooled to 20°C while irradiated with light at a wavelength of 365 nm and an output of 275 mW / LED using an HTE LED array (model number: LUM296LS365) manufactured by Analytical Sales and Services for 16 hours. After 16 hours, the reaction system is removed from the light and the pressure is slowly released from the tube. The sample is then subjected to GC-MS analysis.

[0066] Common procedures using dimethyl ether, diethyl ether, and ethyl acetate as substrates: Add 8.73 mg (0.04 mmol) of 4,4′-difluorobenzophenone, 4.11 mg (0.016 mmol) of Ni(acac)2, and 3.33 mg (0.016 mmol) of neocuproin to an Ace Glass pressure tube (Catalog No.: 8648-42). Place a small stirring blade into the same flask, followed by 2 mL of acetone and the substrate. Purge the gas line through a gas manifold attached to a Schlenklein, then attach the tube to the gas manifold. Fill the reaction tube with 20 psig of CO2, then release the pressure, and repeat this cycle five times. Introduce 100 psig of CO2 and allow it to dissolve in the solvent for approximately 2 minutes, then supply additional gas while maintaining the connection to the gas buffer and shutting off the system from both gases. Subsequently, the reaction system is actively heated to 50°C while irradiated with light at a wavelength of 365 nm and an output of 305 mW / LED using an HTE LED array (model number: LUM296LS365) manufactured by Analytical Sales and Services for 3 hours. After 3 hours, the reaction system is removed from the light and the pressure is slowly released from the tube. The sample is then subjected to GC-MS analysis.

[0067] Preferred embodiments of the present invention, which are fully described and implementable herein, include, but are not limited to, the following:

[0068] 1. A method comprising reacting carbon dioxide with a substrate selected from one or more of alkanes, alkenes, alkynes, ethers, esters, and amines in the presence of a catalyst composition comprising at least one photocatalyst, optionally at least one cocatalyst, optionally at least one ligand, and optionally at least one additive, to produce a carboxylated substrate, wherein the reaction is carried out under light irradiation and optionally in the presence of at least one solvent. 2. The method according to Embodiment 1, wherein the reaction is carried out under irradiation of light having a wavelength range of 250 to 450 nm, more preferably 300 to 400 nm, most preferably 340 to 370 nm, for example 365 nm.

[0069] 3. Methods for each of the preceding embodiments and any combination thereof, wherein the reaction is carried out in the presence of at least one co-catalyst. 4. Methods of the individual preceding embodiments and any combination thereof, wherein the reaction is carried out in the presence of the at least one ligand. 5. Methods of the individual preceding embodiments and any combination thereof, wherein the reaction is carried out in the presence of the at least one additive. 6. Methods of the individual preceding embodiments and any combination thereof, wherein the reaction is carried out in the presence of the at least one solvent. 7. Methods according to individual prior embodiments and any combination thereof, which provide selectivity for carboxylic acid formation of at least 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, and 99%, and preferably have selectivity for all by-products of less than 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, and 1%.

[0070] 8. The method according to each of the preceding embodiments and any combination thereof, wherein the at least one catalyst is selected from at least one of the benzophenones: benzophenone itself, 4,4′-di-tert-butylbenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-difluorobenzophenone, 4,4′-bis(dimethylamino)benzophenone, 4,4′-dihydroxybenzophenone, 4,4′-bisphenylbenzophenone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2-trifluoromethylbenzophenone, 3-fluorobenzophenone, 4-trifluoromethylbenzophenone, 4,4′-diaminobenzophenone, 4,4′-dibromobenzophenone, 4,4′-dicyanobenzophenone, 4-nitrobenzophenone, 2,4-difluorobenzophenone, decafluorobenzophenone, benzophenone imine, 4-tert-butylbenzophenone, and 2,2′,4,4′-tetramethylbenzophenone.

[0071] 9. The presence of at least one of the above cocatalysts, wherein the cocatalyst is nickel(II) nitrate hexahydrate, nickel(II) bis(acetylacetonate), nickel(II) bis(acetylacetonate)-4,4′-dimethoxy-2,2′-bipyridine, nickel(II) bis(2,2,6,6-tetramethyl-3,5-heptanedione), nickel(II) bis(dimethylglyoximate), nickel(II) bis(dimethylglyoximate difluoroborate), nickel(II) bis(diphenyl The method according to each of the individual prior embodiments and any combination thereof, wherein the transition metal cocatalyst is at least one of nickel, cobalt, and palladium compounds / complexes such as ruglioxymate, nickel(II)salen, nickel(II)bis(di-2-pyridinylmethanone), tris(trans-1,2-bis(4-tert-butylphenyl)ethene)nickel(0), cobalt(II)bis(acetylacetonate), and bis(dibenzylideneacetone)palladium(0).

[0072] 10. Methods according to the individual prior embodiments and any combination thereof, wherein the at least one ligand is present and selected from at least one of aromatic amines such as pyridine, bipyridine, and phenanthroline derivatives, examples of which include 2-picolylamine, OMebby(4,4′-dimethoxy-2,2′-bipyridine), OMephen(4,7-dimethoxy-1,10-phenanthroline), and neocuproin(2,9-dimethyl-1,10-phenanthroline).

[0073] 11. Methods according to individual prior embodiments and any combination thereof, wherein the at least one additive is present and selected from at least one of cesium salts such as cesium fluoride, cesium hydroxide, and cesium pivalate, and polycyclic aromatic hydrocarbons such as anthracene.

[0074] 12. The method according to each of the preceding embodiments and any combination thereof, wherein any of the above solvents is present, and is at least one of propylene carbonate, tert-butanol, acetonitrile, dimethyl carbonate, dimethyl sulfoxide, dimethylformamide, dimethoxyethane, hexamethylphosphoramide, tetrahydrofuran, dimethylacetamide, benzonitrile, pyridine, ethyl acetate, acetone, ethylene glycol, and nitromethane, with acetone, methyl acetate, and dimethyl carbonate being preferred, and when an alkane substrate is used, an oxygenated solvent (such as a ketone, carbonate, ester, or alcohol) is preferred.

[0075] 13. Methods of each of the preceding embodiments, excluding Embodiment 12, and any combination thereof, wherein the method is carried out in the absence of the aforementioned arbitrary solvent.

[0076] 14. The carbon dioxide may be added to / present in the reaction as a mixture with one or more other gases, and may be used in any physical form including solid, liquid and gaseous forms, and mixtures thereof, and may be added to / present in the reaction zone as a mixture with one or more other gases, and is preferably pure carbon dioxide and a mixture of carbon dioxide with a non-reactive gas such as nitrogen, noble gas (helium, neon, argon, krypton, xenon and radon), and if a mixture is used, the mixture preferably contains at least 1% by volume of carbon dioxide, more preferably 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50% or more, according to the methods of the individual preceding embodiments and any combination thereof.

[0077] 15. Methods of individual prior embodiments and any combination thereof that achieve substrate conversion rates of at least 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, and 98%.

[0078] The description of the present invention as described above provides methods for manufacturing and using the invention so that a person of ordinary skill in the art can manufacture and use the invention. This enablement is provided in particular with respect to the subject matter of the appended claims which constitute part of this specification. This description is provided in light of specific uses and their requirements. A person skilled in the art will readily understand various modifications to these embodiments. Furthermore, the general principles defined herein can be applied to other embodiments and uses without departing from the spirit and scope of the invention. Thus, the invention is not intended to be limited to the embodiments shown, but rather to be as broad as possible in relation to the principles and features disclosed herein. In this regard, certain embodiments of the invention may not, in a broad sense, demonstrate all the advantages of the invention. Each embodiment, preferred embodiment, aspect, etc., described herein can be used in combination with any other embodiment (whether preferred or not) described herein.

[0079] Some of the aforementioned features can be effectively utilized in certain embodiments without the need for other features, while in other embodiments, advantages can be obtained by using all of the features in combination.

Claims

1. A method comprising reacting carbon dioxide with a substrate selected from one or more of alkanes, alkenes, alkynes, ethers, esters, and amines in the presence of a catalyst composition comprising at least one photocatalyst, optionally at least one cocatalyst, optionally at least one ligand, and optionally at least one additive, to produce a carboxylated substrate, wherein the reaction is carried out under light irradiation and optionally in the presence of at least one solvent.

2. The method according to claim 1, wherein the reaction is carried out under irradiation with light having a wavelength range of 250 to 450 nm.

3. The method according to claim 1, wherein the reaction is carried out in the presence of at least one co-catalyst.

4. The method according to claim 1, wherein the reaction is carried out in the presence of the at least one ligand.

5. The method according to claim 1, wherein the reaction is carried out in the presence of at least one additive.

6. The method according to claim 1, wherein the reaction is carried out in the presence of the at least one solvent.

7. The method according to claim 1, wherein the method provides at least 50% selectivity for carboxylic acid formation of the substrate and less than 20% selectivity for all by-products.

8. The method according to claim 1, wherein the at least one photocatalyst is one or more benzophenones.

9. The method according to claim 1, wherein the at least one cocatalyst is selected from nickel(II) nitrate hexahydrate, nickel(II) bis(acetylacetonate), nickel(II) bis(acetylacetonate)-4,4'-dimethoxy-2,2'-bipyridine, nickel(II) bis(2,2,6,6-tetramethyl-3,5-heptanedione), nickel(II) bis(dimethylglyoximate), nickel(II) bis(dimethylglyoximate difluoroborate), nickel(II) bis(diphenylglyoximate), nickel(II) salen, nickel(II) bis(di-2-pyridinylmethanone), tris(trans-1,2-bis(4-tert-butylphenyl)ethene)nickel(0), cobalt(II) bis(acetylacetonate), and bis(dibenzylideneacetone)palladium(0).

10. The method according to claim 1, wherein the at least one ligand is present, selected from at least one of pyridine, bipyridine, phenanthroline, 2-picolylamine, OMebpy (4,4'-dimethoxy-2,2'-bipyridine), OMephen (4,7-dimethoxy-1,10-phenanthroline), and neocuproin (2,9-dimethyl-1,10-phenanthroline).

11. The method according to claim 1, wherein the at least one additive is present, and is at least one selected from cesium fluoride, cesium hydroxide, cesium pivalate, and anthracene.

12. The method according to claim 1, wherein the aforementioned solvent is present and is at least one selected from propylene carbonate, tert-butanol, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethoxyethane, hexamethylphosphoramide, tetrahydrofuran, dimethylacetamide, benzonitrile, pyridine, ethyl acetate, acetone, ethylene glycol, nitromethane, acetone, methyl acetate, and dimethyl carbonate.

13. The method according to claim 1, wherein the method is carried out in the absence of the arbitrary solvent.

14. The method according to claim 1, wherein the carbon dioxide is pure carbon dioxide.

15. The method according to claim 1, wherein the substrate is an alkane, an alkene, or an alkyne.

16. The method according to claim 1, wherein the substrate is an ether, an ester, or an amine.

17. The method according to claim 1, wherein the substrate is ethane.

18. The method according to claim 1, wherein the substrate is propane.

19. The method according to claim 1, wherein the substrate is dimethyl ether.

20. The method according to claim 1, wherein the substrate is ethyl acetate.

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