How to Oxidize Aldehydes

Abstract

The invention provides a method for converting an aldehyde to a mixture of an alcohol and a carboxylate, the method comprising performing a disproportionation reaction on a composition comprising the aldehyde, a hydroxide, a catalyst, and a solvent, and optionally performing an oxidation reaction on the alcohol to convert the alcohol to more carboxylate.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims the benefit of U.S. Provisional Patent Applications Nos. 63 / 479,676 and 63 / 500,451, filed January 12, 2023 and May 5, 2023, respectively, which are incorporated herein by reference in their entireties.

[0002] Federally sponsored research or development This invention was made with Government support under Contract (FAIN) 2015157 awarded by the National Science Foundation (NSF). The Government has certain rights in this invention. [Background technology]

[0003] Background of the Invention Polyethylene terephthalate (PET), prepared from the esterification reaction between terephthalic acid and ethylene glycol, is the world's second most used commodity polymer by volume. PET is used in applications such as textiles, packaging, photovoltaics, thermoplastics, and many others. PET had an industrial value of approximately $40 billion in 2020. Substitutes for terephthalic acid for use in the preparation of polyesters are highly desirable, given the high market demand for PET.

[0004] One alternative dicarboxylic acid, 2,5-furandicarboxylic acid (FDCA), is already being used in the preparation of polyesters such as polyethylene furanoate (PEF), which is believed to have superior performance characteristics compared to polyethylene terephthalate (PET). Conventional commercial methods for the preparation of FDCA involve converting edible fructose feedstock to FDCA using harsh oxidative conditions. See, for example, Figure 1A for a schematic diagram illustrating a conventional method for the preparation of FDCA from fructose derived from food sources. However, this process requires harsh conditions, multiple solvents, and difficult purification, and provides only moderate yields. As a result, current methods for the preparation of PEF are not cost-effective enough to compete with the preparation of PET.

[0005] An improved method for the preparation of FDCA is provided in Figure 1B, which is a schematic diagram showing the preparation of FDCA from the oxidation and carboxylation of furfural derived from non-edible biomass. The process involves the oxidation of furfural to produce furoate, which is subsequently carboxylated to produce FDCA. Methods for preparing FDCA via the approach shown in Figure 1B are described in International Patent Application Publications WO2016 / 153937 and WO2021 / 158890, both of which are incorporated herein by reference in their entireties.

[0006] As shown in Figure 1B, the first step in the process requires the oxidation of furfural in the presence of hydroxide. However, furfural is unstable under alkaline conditions and undergoes competing degradation pathways. As a result, the yield of FDCA is limited by the conversion of furfural to furoate.

[0007] Similar to the oxidation of furfural, the oxidation of hydroxymethylfurfural (HMF) is known to suffer from decomposition under alkaline conditions, and furthermore, problematic by-products such as 5-formyl-2-furancarboxylic acid (FFCA) are produced, even in trace amounts, which can lead to chain termination during subsequent FDCA polymerization attempts, thereby impairing polymer quality.

[0008] Therefore, there is a need for improved methodologies for the oxidation of aldehydes, such as furfural and HMF, to reduce the costs associated with preparing desirable carboxylates, such as furoate and FDCA. The invention provides such improved methodologies. Summary of the Invention

[0009] Brief Summary of the Invention The invention provides a method for converting an aldehyde to a mixture of an alcohol and a carboxylate, the method comprising conducting a disproportionation reaction on a first composition comprising X moles of the aldehyde, a hydroxide, a catalyst, and a solvent to form a second composition comprising 0.35X to 0.5X moles of the alcohol and 0.35X to 0.5X moles of the carboxylate, wherein the disproportionation reaction is conducted at an initial temperature of 30° C. or less, and wherein the catalyst comprises (a) a support material and (b) a metal.

[0010] The invention also provides a method for converting an aldehyde to a carboxylate, the method comprising: (i) carrying out a disproportionation reaction on a first composition comprising the aldehyde, a hydroxide, a catalyst, and a solvent to form a second composition comprising the carboxylate, an alcohol, the hydroxide, the catalyst, and the solvent; (ii) optionally adjusting the concentrations of the carboxylate, the alcohol, the hydroxide, and / or the catalyst in the second composition; and (iii) carrying out an oxidation reaction on the second composition under an increased oxygen partial pressure and / or an increased temperature compared to the disproportionation reaction to convert more of the alcohol to the carboxylate, wherein the catalyst comprises (a) a support material and (b) a metal.

[0011] The invention also provides a method for producing a carboxylate, the method comprising carrying out an oxidation reaction on furfuryl alcohol in a composition comprising a hydroxide, a catalyst, a solvent, and furfuryl alcohol, wherein the carboxylate is furan-2-carboxylate, and the catalyst comprises (a) a support material and (b) a metal.

[0012] The invention also provides a method for producing a dicarboxylate, the method comprising carrying out an oxidation reaction with 2,5-furandiethanol in a composition comprising a hydroxide, a catalyst, a solvent, and 2,5-furandiethanol, wherein the dicarboxylate is 2,5-furandicarboxylic acid, and the catalyst comprises (a) a support material and (b) a metal.

[0013] The invention further provides 2,5-furandicarboxylic acid (FDCA) prepared from the methods described herein, polymers prepared from the methods described herein, and articles of manufacture comprising the polymers. [Brief explanation of the drawings]

[0014] [Figure 1A]FIG. 1A is a schematic diagram showing a conventional method for the preparation of 2,5-furandicarboxylic acid (FDCA) from fructose derived from food sources. [Figure 1B] FIG. 1B is a schematic diagram showing an improved process for the preparation of 2,5-furandicarboxylic acid (FDCA) from the oxidation and carboxylation of furfural derived from non-edible biomass. [Figure 2] FIG. 2 is a schematic diagram showing an exemplary stirred tank reactor for the oxidation of furfural under batch reaction conditions, where 1 is a pressure transducer, 2 is a mass flow controller, 3 is a heating element, 4 is a motor, 5 is a sample point, 6 is a temperature element, 7 is a pressure transducer, 8 is a level indicator, and 9 is a flow transducer. [Figure 3] FIG. 3 is a schematic diagram showing an exemplary stirred tank reactor for the oxidation of furfural under continuous flow conditions, where 10 is a weight indicator, 11 is a rotameter, 12 is a pressure transducer, 13 is a weight indicator, 14 is a rotameter, 15 is a pressure transducer, 16 is a heating element, 17 is a pressure transducer, 18 is a mass flow controller, 19 is a heating element, 20 is a motor, 21 is a pressure transducer, 22 is a temperature element, 23 is a sample point, 24 is a level indicator, 25 is a flow transducer, 26 is a level indicator, and 27 is a flow transducer. [Figure 4] Figures 4A-4D provide analytical tools for the analysis of furfural oxidation reactions. Figures 4A-4C are concentration calibration curves for standard solutions of furfural (Figure 4A), furoate (Figure 4B), and furfuryl alcohol (Figure 4C). Figure 4D is an HPLC trace of a product sample from a batch furfural oxidation reaction diluted in TEA(OAc) buffer. [Figure 5]Figures 5A-5D are graphs showing the reaction progress of furfural consumption, furoate yield, furfuryl alcohol yield, and total Cannizzaro (disproportionation reaction) yield under alkaline conditions using initial reaction conditions of 1.0 M furfural and 1.0 M CsOH (Figure 5A), 1.0 M furfural and 0.5 M CsOH (Figure 5B), 0.75 M furfural and 0.75 M CsOH (Figure 5C), 1.0 M furfural and 0.5 M CsCO (Figure 5D), and 1.0 M furfural and 1.0 M CsCO (Figure 5E). [Figure 6] Figures 6A-6C are graphs showing the reaction progress of the Au / TiO2-catalyzed Cannizzaro disproportionation reaction of furfural. Figure 6A shows the rate acceleration of furfural consumption by the Cannizzaro disproportionation reaction in the presence of Au / TiO2. Figure 6B shows a comparison of the rates of furfural consumption in the presence of Au / TiO2, bare oxide catalyst support, and without catalyst. Figure 6C shows a comparison of the rates of furfural consumption for reactions with varying initial CsOH concentrations and catalyst loadings. "FF" is furfural, "FA" is furoate, and "FOH" is furfuryl alcohol. [Figure 7] FIG. 7 is a schematic diagram showing an exemplary multi-channel trickle-bed reactor system for catalytic oxidation of furfural Cannizzaro (disproportionation) products to produce additional furoate under continuous flow conditions, where 1 is an HPLC pump, 2 is a mass flow controller, 3 is a pressure transducer, and 4 is a pressure regulator. [Figure 8]Figure 8 is a graph showing the reaction progress of the Au / TiO2-catalyzed oxidation reaction of the furfural Cannizzaro (disproportionation) reaction product to produce additional furoate in a continuous trickle-bed reactor system. The yield of furoate over time is shown, either calculated from the amount of furfuryl alcohol in the prepared feed mixture or extrapolated from furfural, assuming an initial Cannizzaro (disproportionation) step with a quantitative yield of the disproportionation reaction product. The yields shown were averaged over 12 parallel reactor channels loaded with Au / TiO2 catalyst with liquid hourly space velocity (LHSV) values ​​ranging from 2.25 to 4.75 h-1. "TOS" is time on stream, "FF" is furfural, "FA" is furoate, and "FOH" is furfuryl alcohol. DETAILED DESCRIPTION OF THE INVENTION

[0015] Detailed Description of the Invention The invention provides a method for converting an aldehyde to a mixture of an alcohol and a carboxylate. The method includes carrying out a disproportionation reaction on a first composition comprising X moles of an aldehyde, a hydroxide, a catalyst, and a solvent to form a second composition comprising 0.35X to 0.5X moles of the alcohol and 0.35X to 0.5X moles of the carboxylate. The disproportionation reaction is carried out at an initial temperature of 30°C or less, and the catalyst comprises (a) a support material and (b) a metal.

[0016] As used herein, the term "disproportionation reaction" refers to a redox reaction in which one compound or moiety of an intermediate oxidation state (i.e., an aldehyde) is converted to two compounds or moieties, one of which is of a higher oxidation state (i.e., a carboxylate) and the other of which is of a lower oxidation state (i.e., an alcohol). In other words, one equivalent of aldehyde is converted to one-half equivalents of alcohol and one-half equivalents of carboxylate.

[0017] That is, in the event of 100% conversion of the aldehyde to alcohol and carboxylate, X moles of the aldehyde are converted to 0.5X moles of the alcohol and 0.5X moles of the carboxylate. In contrast, in the event of 70% conversion of the aldehyde to alcohol and carboxylate, X moles of the aldehyde are converted to 0.35X moles of the alcohol and 0.35X moles of the carboxylate. Thus, in some embodiments, a first composition comprising X moles of aldehyde is converted to a second composition comprising 0.35X to 0.5X moles of alcohol and 0.35X to 0.5X moles of carboxylate, which corresponds to a 70% to 100% yield of the disproportionation reaction. In some embodiments, a first composition containing X moles of aldehyde is converted to a second composition containing 0.4X to 0.5X moles of alcohol and 0.4X to 0.5X moles of carboxylate, which corresponds to an 80% to 100% yield of the disproportionation reaction. In some embodiments, a first composition containing X moles of aldehyde is converted to a second composition containing 0.45X to 0.5X moles of alcohol and 0.45X to 0.5X moles of carboxylate, which corresponds to a 90% to 100% yield of the disproportionation reaction. The number of moles (X) is not particularly limited, so long as the disproportionation reaction can provide at least 70% conversion of the aldehyde to alcohol and carboxylate. In other words, the scale of the reaction is not particularly limited, so long as the disproportionation reaction can provide at least 70% conversion of the aldehyde to alcohol and carboxylate.

[0018] The method includes carrying out a disproportionation reaction on a first composition including X moles of an aldehyde, a hydroxide, a catalyst, and a solvent.

[0019] The aldehyde can be any suitable compound containing one or more aldehyde functional groups. In some embodiments, the aldehyde contains a single aldehyde functional group that can be oxidized to a carboxylate and reduced to an alcohol. For example, the aldehyde can be an alkyl-based aldehyde, a cycloalkyl-based aldehyde, a heteroalkyl-based aldehyde, a heterocyclic-based aldehyde, an aromatic aldehyde, a heteroaromatic aldehyde, etc. In some embodiments, the aldehyde is furfural, hydroxymethylfurfural (i.e., 5-(hydroxymethyl)furfural or HMF), benzaldehyde, acetaldehyde, phenylacetaldehyde, or hydroxypivaldehyde. In certain embodiments, the aldehyde is furfural, which can be oxidized to furan-2-carboxylate and reduced to furfuryl alcohol. In certain embodiments, the aldehyde is hydroxymethylfurfural (i.e., 5-(hydroxymethyl)furfural or HMF), which can be oxidized to 5-hydroxymethyl-2-furoic acid and reduced to 2,5-furandiethanol.

[0020] The disproportionation reaction is carried out in the presence of a hydroxide. The hydroxide can be any suitable compound capable of generating free hydroxide ions in solution. Generally, the free hydroxide ions in solution are generated by a metal hydroxide. For example, the hydroxide can be a metal hydroxide selected from alkali metal hydroxides, alkaline earth metal hydroxides, and combinations thereof. In some embodiments, the hydroxide is an alkali metal hydroxide, such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, or a combination thereof. In certain embodiments, the hydroxide is cesium hydroxide.

[0021] Any suitable amount of hydroxide can be added to the first composition. To achieve 100% theoretical conversion of aldehyde to carboxylate and alcohol, at least 0.5 equivalents of hydroxide are required. That is, in some embodiments, at least 0.5 equivalents (i.e., at least 0.5X moles) of hydroxide are added to the first composition. In some embodiments, at least 1 equivalent (e.g., at least X moles) of hydroxide is added to the first composition. For example, about 0.5X moles, about 0.6X moles, about 0.7X moles, about 0.8X moles, about 0.9X moles, about X moles, about 1.1X moles, about 1.2X moles, about 1.3X moles, about 1.4X moles, about 1.5X moles, about 1.6X moles, about 1.7X moles, about 1.8X moles, about 1.9X moles, or about 2X moles of hydroxide can be added to the first composition. Typically, about 6X moles or less of hydroxide is present in the first composition. In some embodiments, about 0.5X moles to about 3X moles of hydroxide are added to the first composition. In certain embodiments, about 0.5X moles to about 2X moles of hydroxide are added to the first composition. In a preferred embodiment, about X moles to about 2X moles are added to the first composition.

[0022] The disproportionation reaction is carried out in the presence of a catalyst comprising (a) a support material and (b) a metal. The support material can be any suitable material capable of supporting (e.g., firmly anchoring) the metal. For example, the support material can include a metal oxide (e.g., TiO2, ZrO2, SiO2, Al2O3, MnO, MgO, FeO, CeO2, Fe2O3, etc.), a carbon material (e.g., activated carbon or carbon black), a metal-organic framework (MOF), a mineral (e.g., talc or hydrotalcite), etc. In some embodiments, the support material comprises TiO2, ZrO2, SiO2, Al2O3, MgO, CeO2, hydrotalcite, a carbon material, or a combination thereof. In certain embodiments, the support material comprises TiO2. The metal can be any suitable metal capable of catalyzing the disproportionation reaction. For example, the metal can be or contain cobalt, nickel, copper, zinc, ruthenium, rhodium, palladium, silver, cadmium, iridium, platinum, gold, mercury, or a combination thereof. In some embodiments, the metal includes gold, platinum, silver, palladium, nickel, ruthenium, copper, cobalt, or a combination thereof. In particular embodiments, the metal includes gold, platinum, palladium, or a combination thereof. The metal can be in any suitable form or configuration. In some embodiments, the metal is in the form of metal nanoparticles. As used herein, the term "nanoparticle" refers to a submicron-sized entity made of a pure metal (e.g., cobalt, nickel, copper, zinc, ruthenium, rhodium, palladium, silver, cadmium, iridium, platinum, gold, or mercury) or a derivative thereof (e.g., oxide, hydroxide, sulfide, phosphate, fluoride, or chloride). In certain embodiments, the metal nanoparticles are submicron-sized entities made of pure metal (e.g., cobalt, nickel, copper, zinc, ruthenium, rhodium, palladium, silver, cadmium, iridium, platinum, gold, or mercury). For example, the metal can include gold nanoparticles, platinum nanoparticles, palladium nanoparticles, or combinations thereof. In some particular embodiments, the metal includes gold nanoparticles. The support material and the metal can be attached to each other via any suitable means.For example, the support material and the metal may be attached to one another through interactions such as covalent interactions, ionic interactions, coordination interactions, van der Waals interactions, etc. In certain embodiments, the catalyst comprises gold nanoparticles supported on TiO2.

[0023] The catalyst can be present in any physical form in the solution. Generally, the catalyst is a solid in the solution and can be present as a coating, beads, pellets, powder, porous media, or a combination thereof. In some embodiments, the catalyst is in the form of pellets, powder, or a combination thereof. Without wishing to be bound by any particular theory, it is believed that the increased surface area of ​​the catalyst improves the rate of the disproportionation and / or oxidation reaction. That is, in some embodiments, the catalyst is present in a solution of about 5 m 2 / g to about 500m 2 / g, for example, about 5m 2 / g to about 200m 2 / g, approx. 5m 2 / g to about 100m 2 / g, approx. 5m 2 / g to about 50m 2 / g, approx. 10m 2 / g to about 500m 2 / g, approx. 10m 2 / g to about 200m 2 / g, approx. 10m 2 / g to about 100m 2 / g, or approximately 10 m 2 / g to about 50m 2 In certain embodiments, the catalyst comprises a porous support (e.g., TiO2) having a porosity of about 10 m / g. 2 / g to about 100m 2 The catalyst comprises a porous support (e.g., TiO) having a porosity of 0.1 μm / g. Alternatively, or in addition, the catalyst is in the form of a powder having an average particle size of 500 μm or less, 400 μm or less, 300 μm or less, 200 μm or less, or 100 μm or less. In certain embodiments, the catalyst is in the form of a powder having an average particle size of 100 μm or less.

[0024] Any suitable amount of catalyst can be added to the first composition. For example, the first composition can contain a catalyst in an amount such that there is about 0.01 mol% to about 50 mol% of metal relative to the aldehyde. In some embodiments, the catalyst is present in an amount such that there is about 0.01 mol% to about 5 mol% of metal, e.g., about 0.01 mol% to about 4 mol% of metal, about 0.01 mol% to about 3 mol% of metal, about 0.01 mol% to about 2 mol% of metal, about 0.01 mol% to about 1 mol% of metal, about 0.01 mol% to about 0.5 mol% of metal, about 0.1 mol% to about 5 mol% of metal, about 0.1 mol% to about 4 mol% of metal, about 0.1 mol% to about 3 mol% of metal, about 0.1 mol% to about 2 mol% of metal, about 0.1 mol% to about 1 mol% of metal, or about 0.1 mol% to about 0.5 mol% of metal. In some embodiments, the catalyst is present in an amount such that there is about 0.1 mol % to about 3 mol % metal relative to the aldehyde, hi certain embodiments, the catalyst is present in an amount such that there is about 0.1 mol % to about 1 mol % metal relative to the aldehyde.

[0025] The disproportionation reaction is carried out in the presence of a solvent. Generally, the solvent comprises water (e.g., deionized water) and optionally one or more water-miscible organic solvents. Examples of organic solvents that can be used include alcohols such as propenyl alcohol, isopropyl alcohol, ethanol, 1-propanol, methanol, and 1-hexanol; ketones such as acetone, diacetone alcohol, and methyl ethyl ketone; esters such as ethyl formate, propyl formate, ethyl acetate, methyl acetate, methyl lactate, butyl lactate, and ethyl lactate; ethers containing sulfoxides such as dimethyl sulfoxide (DMSO), tetrahydrofuran, dioxane, and diglyme; amides such as N,N-dimethylformamide, dimethylimidazolidinone, and N-methylpyrrolidone; polyhydric alcohols and derivatives thereof such as ethylene glycol, glycerin, diethylene glycol, and diethylene glycol monomethyl ether; and nitrogen-containing organic compounds such as acetonitrile, amylamine, isopropylamine, imidazole, and dimethylamine. In some embodiments, the solvent is water, i.e., no organic solvent is present.

[0026] The disproportionation reaction can be carried out at any suitable initial aldehyde concentration. For example, the disproportionation reaction can be carried out at an initial aldehyde concentration of 0.1 M or greater, 0.5 M or greater, 1 M or greater, 1.1 M or greater, 1.2 M or greater, 1.3 M or greater, 1.4 M or greater, 1.5 M or greater, or 2 M or greater. Without wishing to be bound by any particular theory, it is believed that the method of the present invention is particularly well suited to concentrated aldehyde solutions. Due to the efficient catalytic conversion of aldehyde to alcohol and carboxylate, only a limited amount of aldehyde is lost to decomposition pathways. As a result, the method of the present invention can be carried out under more concentrated conditions than conventional methods for aldehyde oxidation. That is, in some embodiments, the initial aldehyde concentration in the first composition is at least 1 M. In certain embodiments, the initial concentration of the aldehyde in the first composition is at least 1.5M.

[0027] In some embodiments, the disproportionation reaction is carried out at an initial temperature of 30° C. or less. For example, the disproportionation reaction can be carried out at an initial temperature of 25° C. or less, 20° C. or less, 15° C. or less, or 10° C. or less. Generally, the disproportionation reaction is carried out at an initial temperature of 0° C. or greater. For example, the disproportionation reaction can be carried out at an initial temperature of 0° C. to 30° C., 0° C. to 25° C., 0° C. to 20° C., 0° C. to 15° C., or 0° C. to 10° C. In some embodiments, the disproportionation reaction is carried out at an initial temperature of room temperature (e.g., about 20° C. to about 30° C.), i.e., without heating the reaction. In other words, a first composition containing X moles of aldehyde can be converted to a second composition containing 0.35X to 0.5X moles of alcohol and 0.35X to 0.5X moles of carboxylate at an initial temperature of 30° C. or less. That is, in some embodiments, the disproportionation reaction reaches at least 70% conversion at an initial temperature of 30° C. or less. Without wishing to be bound by any particular theory, the disproportionation reaction may be exothermic, such that the temperature increases without the application of any external heat. As a result, the temperature may increase above the initial temperature during the course of the disproportionation reaction. In other embodiments, the disproportionation reaction is carried out (e.g., carried out completely) at a temperature of 30°C or less. For example, the disproportionation reaction can be carried out (e.g., carried out completely) at a temperature of 25°C or less, 20°C or less, 15°C or less, or 10°C or less. For example, the disproportionation reaction can be carried out (e.g., carried out completely) at a temperature of 0°C to 30°C, 0°C to 25°C, 0°C to 20°C, 0°C to 15°C, or 0°C to 10°C. In certain embodiments, the disproportionation reaction is carried out (e.g., carried out completely) at a temperature of 0°C or greater. In some embodiments, the disproportionation reaction is carried out (e.g., carried out completely) at room temperature (e.g., about 20° C. to about 30° C.), i.e., without heating the reaction. In other words, a first composition containing X moles of aldehyde can be converted to a second composition containing 0.35X to 0.5X moles of alcohol and 0.35X to 0.5X moles of carboxylate at a temperature of 30° C. or less. That is, in some embodiments, the disproportionation reaction reaches at least 70% conversion at a temperature of 30° C. or less.

[0028] In some embodiments, the disproportionation reaction is carried out at atmospheric pressure of O, i.e., at or below 160 mmHg O (21.3 kPa) at sea level. For example, the disproportionation reaction can be carried out at atmospheric pressure (e.g., exposed to air) or under an inert atmosphere (e.g., under argon or nitrogen). In other words, increased oxygen pressure is not required and, in some embodiments, may be a deterrent for the conversion of aldehydes to alcohols and carboxylates. In some embodiments, the disproportionation reaction is carried out at atmospheric pressure, i.e., about 160 mmHg O (21.3 kPa) at sea level.

[0029] The disproportionation reaction can be carried out under batch reaction conditions or continuous flow conditions. As used herein, the term "batch reaction conditions" refers to a process in which reactants are added to a reactor, the reaction is carried out for a set period of time, the product is removed from the reactor, and the product is optionally isolated and / or purified. In some embodiments, the disproportionation reaction is carried out in a fixed-bed reactor or a stirred-tank reactor under batch reaction conditions. An exemplary system for carrying out a batch reaction in a stirred-tank reactor is provided in FIG. 2. As used herein, the term "continuous flow conditions" refers to a process in which one or more reactants are continuously added to a reactor, the reaction is carried out continuously, and the product is removed from the reactor as the reaction proceeds. For example, continuous flow conditions for the disproportionation reaction can include passing a solution containing an aldehyde, a metal hydroxide, and a solvent through a reaction vessel containing a catalyst so that the reaction can be carried out continuously. In some embodiments, the disproportionation reaction is carried out under continuous flow conditions in a tubular reactor, a fixed bed reactor, a fluidized bed reactor, a trickle bed reactor, or a continuous stirred tank reactor. An exemplary system for carrying out a continuous flow reaction in a continuous flow stirred tank reactor is provided in Figure 3. In certain embodiments, the disproportionation reaction is carried out using a fixed bed reactor under batch reaction conditions or continuous flow conditions.

[0030] In some embodiments, the method further includes isolating and optionally purifying the mixture of alcohol and carboxylate. The alcohol and / or carboxylate can be isolated by any suitable means. For example, the alcohol and / or carboxylate can be extracted from the reaction mixture, crystallized from the reaction mixture, distilled from the reaction mixture, or any combination thereof. Alternatively, or in addition, the mixture of alcohol and carboxylate can be purified by any suitable means. For example, the alcohol and / or carboxylate can be purified by recrystallization, distillation, column chromatography, filtration, dialysis, or a combination thereof.

[0031] Whether or not the method further comprises isolating and optionally purifying the mixture of alcohol and carboxylate, the method can further comprise performing an oxidation reaction on the alcohol to convert the alcohol to the carboxylate (e.g., to produce more carboxylate or to produce a dicarboxylate). For example, the oxidation reaction can be performed directly on the resulting reaction mixture from the disproportionation reaction, the oxidation reaction can be performed on an isolated mixture of alcohol and carboxylate, or the oxidation reaction can be performed on a purified alcohol. In some embodiments, the oxidation reaction is performed directly on the resulting reaction mixture from the disproportionation reaction. In other words, the oxidation reaction does not require isolating and optionally purifying the mixture of alcohol and carboxylate.

[0032] In some embodiments, the oxidation reaction is carried out in the presence of a hydroxide, a catalyst, and a solvent. The hydroxide, catalyst, and solvent of the oxidation reaction can be the same as or different from the hydroxide, catalyst, and solvent of the disproportionation reaction. Whether the hydroxide, catalyst, and solvent of the oxidation reaction are the same as or different from the hydroxide, catalyst, and solvent of the disproportionation reaction, the hydroxide, catalyst, and solvent of the oxidation reaction are as described herein for the disproportionation reaction. In some embodiments, the hydroxide, catalyst, and solvent are the same for the disproportionation reaction and the oxidation reaction. In other embodiments, one or more of the hydroxide, catalyst, and solvent are different for the disproportionation reaction and the oxidation reaction.

[0033] In some embodiments, the oxidation reaction is carried out in the presence of a support material including a metal oxide (e.g., TiO, ZrO, SiO, AlO, MnO, MgO, FeO, CeO, FeO, etc.), a carbon material (e.g., activated carbon or carbon black), a metal-organic framework (MOF), a mineral (e.g., talc or hydrotalcite), etc. In some embodiments, the support material for the oxidation reaction includes TiO, ZrO, SiO, AlO, MgO, CeO, hydrotalcite, a carbon material, or a combination thereof. In certain embodiments, the support material for the oxidation reaction includes TiO or a carbon material. The metal can be any suitable metal capable of catalyzing the oxidation reaction. For example, the metal can be or include cobalt, nickel, copper, zinc, ruthenium, rhodium, palladium, silver, cadmium, iridium, platinum, gold, mercury, or a combination thereof. In some embodiments, the metal for the oxidation reaction comprises gold, platinum, silver, palladium, nickel, ruthenium, or a combination thereof. In particular embodiments, the metal for the oxidation reaction comprises gold, platinum, palladium, or a combination thereof. All other characteristics of the support material and metal for the oxidation reaction are as described above for the support material and metal for the disproportionation reaction.

[0034] Any suitable amount of hydroxide can be used in the oxidation reaction. In some embodiments, at least 1 equivalent of hydroxide relative to the alcohol is present in the second composition (e.g., the composition used for the oxidation reaction). For example, at least about 1.1 equivalents relative to the alcohol, at least about 1.2 equivalents relative to the alcohol, at least about 1.3 equivalents relative to the alcohol, at least about 1.4 equivalents relative to the alcohol, at least about 1.5 equivalents relative to the alcohol, at least about 1.6 equivalents relative to the alcohol, at least about 1.7 equivalents relative to the alcohol, at least about 1.8 equivalents relative to the alcohol, at least about 1.9 equivalents relative to the alcohol, or at least about 2 equivalents relative to the alcohol can be present in the second composition. Typically, no more than about 6 equivalents of hydroxide relative to the alcohol are present in the second composition. In some embodiments, from about 1 to about 4 equivalents of hydroxide relative to the alcohol are present in the second composition. In certain embodiments, from about 1 to about 3 equivalents of hydroxide relative to the alcohol are present in the second composition.

[0035] Any suitable amount of catalyst can be used in the oxidation reaction. For example, the second composition can contain a catalyst in an amount such that there is about 0.01 mol% to about 50 mol% of metal relative to the alcohol. In some embodiments, the catalyst is present in an amount such that there is about 0.01 mol% to about 5 mol% of metal, for example, about 0.01 mol% to about 4 mol% of metal, about 0.01 mol% to about 3 mol% of metal, about 0.01 mol% to about 2 mol% of metal, about 0.01 mol% to about 1 mol% of metal, about 0.01 mol% to about 0.5 mol% of metal, about 0.1 mol% to about 5 mol% of metal, about 0.1 mol% to about 4 mol% of metal, about 0.1 mol% to about 3 mol% of metal, about 0.1 mol% to about 2 mol% of metal, about 0.1 mol% to about 1 mol% of metal, or about 0.1 mol% to about 0.5 mol% of metal. In certain embodiments, the catalyst is present in an amount such that there is about 0.1 mole % to about 2 mole % metal relative to alcohol.

[0036] Generally, the oxidation reaction is carried out under an increased oxygen partial pressure and / or at an increased temperature compared to the disproportionation reaction. For example, the oxidation reaction can be carried out at an O partial pressure greater than about 160 mmHg O (21.3 kPa) (e.g., an oxygen partial pressure of at least 100 kPa, an oxygen partial pressure of at least 500 kPa, or an oxygen partial pressure of at least 1 MPa). In some embodiments, the oxidation reaction is carried out under an oxygen partial pressure of about 22 kPa to about 2 MPa, about 22 kPa to about 1 MPa, about 22 kPa to about 500 kPa, about 22 kPa to about 100 kPa, about 50 kPa to about 2 MPa, about 50 kPa to about 1 MPa, about 50 kPa to about 500 kPa, about 50 kPa to about 100 kPa, about 100 kPa to about 2 MPa, about 100 kPa to about 1 MPa, or about 100 kPa to about 500 kPa. Alternatively, or in addition, the oxidation reaction can be carried out at a temperature above 30° C. (e.g., a temperature of 30° C. to 100° C., a temperature of 30° C. to 80° C., a temperature of 40° C. to 100° C., a temperature of 40° C. to 80° C., a temperature of 50° C. to 100° C., a temperature of 50° C. to 80° C., a temperature of 55° C. to 100° C., a temperature of 55° C. to 80° C., a temperature of 60° C. to 100° C., or a temperature of 60° C. to 80° C.). In some embodiments, the oxidation reaction is carried out at a temperature of 55° C. to 80° C. In certain embodiments, the oxidation reaction is carried out at a temperature of 55° C. to 80° C. In some embodiments, the oxidation reaction is carried out under an increased partial pressure of oxygen and at an increased temperature compared to the disproportionation reaction.

[0037] The oxidation reaction can be carried out in the same reaction vessel as the disproportionation reaction or in a separate reaction vessel. Alternatively, or in addition, the oxidation reaction can be carried out under batch reaction conditions or continuous flow conditions. In some embodiments, the oxidation reaction is carried out in a fixed-bed reactor or a stirred-tank reactor under batch reaction conditions. An exemplary system for carrying out a batch reaction in a stirred-tank reactor is provided in FIG. 2. In some embodiments, the oxidation reaction is carried out under continuous flow conditions in a tubular reactor, a fixed-bed reactor, a fluidized-bed reactor, a trickle-bed reactor, or a continuous stirred-tank reactor. For example, continuous flow conditions for the oxidation reaction can include passing a solution containing the carboxylate, the alcohol, the metal hydroxide, and the solvent through a reaction vessel containing the catalyst so that the reaction can be carried out continuously. An exemplary system for carrying out a continuous flow reaction in a continuous-flow stirred-tank reactor is provided in FIG. 3. In certain embodiments, the oxidation reaction is carried out using a trickle-bed reactor under batch reaction conditions or continuous flow conditions. Whether the oxidation reaction is carried out under batch reaction conditions or continuous flow conditions, the reaction vessel can be pressurized and / or heated, as described herein, so as to carry out the oxidation reaction under increased oxygen partial pressure and / or increased temperature compared to the disproportionation reaction.

[0038] The invention further provides a method for converting an aldehyde to a carboxylate. The method includes (i) carrying out a disproportionation reaction on a first composition comprising an aldehyde, a hydroxide, a catalyst, and a solvent to form a second composition comprising a carboxylate, an alcohol, the hydroxide, the catalyst, and the solvent; (ii) optionally adjusting the concentrations of the carboxylate, the alcohol, the hydroxide, and / or the catalyst in the second composition; and (iii) carrying out an oxidation reaction on the second composition under an increased oxygen partial pressure and / or at an increased temperature compared to the disproportionation reaction to convert more of the alcohol to the carboxylate, wherein the catalyst comprises (a) a support material and (b) a metal. In some embodiments, the method includes adjusting the concentrations of the carboxylate, the alcohol, the hydroxide, and / or the catalyst in the second composition. In other embodiments, the method does not include adjusting the concentrations of the carboxylate, the alcohol, the hydroxide, and / or the catalyst in the second composition. All aspects of the disproportionation reaction, aldehyde, hydroxide, catalyst, solvent, carboxylate, alcohol, oxidation reaction, oxygen partial pressure, and temperature are as described herein.

[0039] That is, in some embodiments, the method includes (i) performing a disproportionation reaction on a first composition to form a second composition, (ii) optionally adjusting the concentration of the second composition, and (iii) performing an oxidation reaction on the second composition. For example, after performing the disproportionation reaction, the amounts of hydroxide, catalyst, and solvent in the second composition can be adjusted to increase concentration, decrease concentration, increase catalyst loading, decrease catalyst loading, replace depleted reagents, or a combination thereof.

[0040] In some embodiments, the disproportionation reaction is carried out until most of the aldehyde is consumed before (ii) optionally adjusting the concentration of the second composition and (iii) performing an oxidation reaction on the second composition. In other words, in some embodiments, the disproportionation reaction is carried out until most of the aldehyde is consumed before (a) optionally adjusting the concentration of the second composition and (b) increasing the oxygen partial pressure and / or temperature. For example, (ii) optionally adjusting the concentration of the second composition and (iii) performing an oxidation reaction on the second composition can be carried out after at least 50% of the aldehyde is consumed, after at least 60% of the aldehyde is consumed, after at least 70% of the aldehyde is consumed, after at least 80% of the aldehyde is consumed, after at least 90% of the aldehyde is consumed, after at least 95% of the aldehyde is consumed, or after at least 99% of the aldehyde is consumed. In other words, in some embodiments, at least 50% of the aldehyde is consumed, at least 60% of the aldehyde is consumed, at least 70% of the aldehyde is consumed, at least 80% of the aldehyde is consumed, at least 90% of the aldehyde is consumed, at least 95% of the aldehyde is consumed, or at least 99% of the aldehyde is consumed before increasing the partial pressure of oxygen and / or the temperature. Without wishing to be bound by any particular theory, it is believed that the present invention provides increased conversion of the aldehyde to the carboxylate by first converting the aldehyde to a more stable alcohol and carboxylate before applying more severe oxidation conditions (i.e., increased partial pressure of oxygen and / or increased temperature). In some embodiments, at least 80% of the aldehyde is consumed before increasing the partial pressure of oxygen and / or the temperature. In certain embodiments, at least 90% of the aldehyde is consumed before increasing the partial pressure of oxygen and / or the temperature.

[0041] In some embodiments, the aldehyde is furfural, and the oxidation reaction converts a mixture of furan-2-carboxylate and furfuryl alcohol to additional furan-2-carboxylate. In certain embodiments, the oxidation reaction is carried out in the presence of (a) a metal hydroxide selected from alkali metal hydroxides, alkaline earth metal hydroxides, and combinations thereof, (b) a carbon material, and (c) a metal comprising gold, platinum, palladium, or a combination thereof.

[0042] In some embodiments, the aldehyde is hydroxymethylfurfural, and the oxidation reaction directly converts a mixture of 5-hydroxymethyl-2-furoic acid and 2,5-furandiimethanol to the dicarboxylate, where the dicarboxylate is 2,5-furandicarboxylic acid. In certain embodiments, the oxidation reaction is carried out in the presence of (a) a metal hydroxide selected from alkali metal hydroxides, alkaline earth metal hydroxides, and combinations thereof, (b) a carbon material, and (c) a metal comprising gold, platinum, palladium, or a combination thereof.

[0043] In some embodiments, the methods described herein further include converting a carboxylate (e.g., furan-2-carboxylate or 5-hydroxymethyl-2-furoic acid) to a dicarboxylate (e.g., 2,5-furandicarboxylic acid). In some embodiments, the carboxylate (e.g., furan-2-carboxylate) is converted to a dicarboxylate (e.g., 2,5-furandicarboxylic acid) by performing a carboxylation reaction on the carboxylate with (i) a carbonate in the presence of carbon dioxide or (ii) a hydroxide in the presence of carbon dioxide to form the dicarboxylate. In certain embodiments, the carboxylate is furan-2-carboxylate and the dicarboxylate is 2,5-furandicarboxylic acid. For exemplary procedures for converting a carboxylate to a dicarboxylate (e.g., furan-2-carboxylate to 2,5-furandicarboxylic acid), see International Patent Application Publications WO2016 / 153937 and WO2021 / 158890.

[0044] As used herein, the terms "carboxylate" and "carboxylic acid" can be used interchangeably to refer to the oxidation products described herein. Similarly, the terms "dicarboxylate" and "dicarboxylic acid" can be used interchangeably to refer to the oxidation products described herein. In other words, any of the oxidation products described herein can exist in acid form, ionized form, or salt form. In some embodiments, the carboxylate is a dicarboxylate.

[0045] In some embodiments, the carboxylation reaction is carried out in the presence of a carbonate salt. The carbonate salt can be any suitable compound capable of generating free carbonate ions in solution. Generally, the free carbonate ions in solution are generated by a metal carbonate salt. For example, the carbonate salt can be a metal carbonate salt selected from alkali metal carbonates, alkaline earth metal carbonates, and combinations thereof. In some embodiments, the carbonate salt is an alkali metal carbonate salt, such as sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, or a combination thereof. In certain embodiments, the carbonate salt is cesium carbonate.

[0046] In some embodiments, the carboxylation reaction is carried out at a CO partial pressure greater than the partial pressure of CO at atmospheric pressure. In some embodiments, the carboxylation reaction is carried out at a carbon dioxide partial pressure of at least 100 kPa, at least 500 kPa, or at least 1 MPa. In some embodiments, the carboxylation reaction is carried out under a carbon dioxide partial pressure of about 50 kPa to about 1 MPa, about 50 kPa to about 500 kPa, about 50 kPa to about 100 kPa, about 100 kPa to about 1 MPa, or about 100 kPa to about 500 kPa.

[0047] The invention also provides a method for producing a carboxylate, the method comprising carrying out an oxidation reaction of furfuryl alcohol in a composition comprising a hydroxide, a catalyst, a solvent, and furfuryl alcohol, wherein the carboxylate is furan-2-carboxylate, and the catalyst comprises (a) a support material and (b) a metal. In some embodiments, the method for producing a carboxylate comprises carrying out an oxidation reaction of a mixture of furan-2-carboxylate and furfuryl alcohol in a composition comprising a hydroxide, a catalyst, a solvent, and the mixture of furan-2-carboxylate and furfuryl alcohol. In some embodiments, the oxidation reaction is carried out in the presence of (a) a metal hydroxide selected from alkali metal hydroxides, alkaline earth metal hydroxides, and combinations thereof, (b) a carbon material, and (c) a metal comprising gold, platinum, palladium, or a combination thereof. In certain embodiments, the oxidation reaction is carried out in the presence of a metal hydroxide selected from alkali metal hydroxides, alkaline earth metal hydroxides, and combinations thereof, and platinum on carbon.

[0048] For example, a mixture of furan-2-carboxylate and furfuryl alcohol can be used as a starting material in the oxidation reaction. The mixture (e.g., starting material mixture) can contain any suitable amount of furan-2-carboxylate and furfuryl alcohol. For example, the mixture can contain 0.35X to 0.65X moles of furan-2-carboxylate and 0.35X to 0.65X moles of furfuryl alcohol, 0.40X to 0.60X moles of furan-2-carboxylate and 0.40X to 0.60X moles of furfuryl alcohol, or 0.45X to 0.55X moles of furan-2-carboxylate and 0.45 to 0.55 moles of furfuryl alcohol. In some embodiments, the mixture (e.g., starting material mixture) contains 0.35X to 0.65X moles of furan-2-carboxylate and 0.35X to 0.65X moles of furfuryl alcohol. In certain embodiments, the mixture (e.g., starting material mixture) comprises 0.45X to 0.55X moles of furan-2-carboxylate and 0.45X to 0.55X moles of furfuryl alcohol.

[0049] The invention also provides a method for producing a dicarboxylate, the method comprising carrying out an oxidation reaction of 2,5-furan dimethanol in a composition comprising a hydroxide, a catalyst, a solvent, and 2,5-furan dimethanol, wherein the dicarboxylate is 2,5-furan dicarboxylic acid, and the catalyst comprises (a) a support material and (b) a metal. In some embodiments, the method for producing a dicarboxylate comprises carrying out an oxidation reaction of a mixture of 5-hydroxymethyl-2-furoic acid and 2,5-furan dimethanol in a composition comprising a hydroxide, a catalyst, a solvent, and the mixture of 5-hydroxymethyl-2-furoic acid and 2,5-furan dimethanol. In some embodiments, the oxidation reaction is carried out in the presence of a metal hydroxide selected from alkali metal hydroxides, alkaline earth metal hydroxides, and combinations thereof, a carbon material, and a metal including gold, platinum, palladium, or a combination thereof. In certain embodiments, the oxidation reaction is carried out in the presence of a metal hydroxide selected from alkali metal hydroxides, alkaline earth metal hydroxides, and combinations thereof, and platinum on carbon.

[0050] For example, a mixture of 5-hydroxymethyl-2-furoic acid and 2,5-furan diethanol can be used as a starting material in the oxidation reaction. The mixture (e.g., starting material mixture) can contain any suitable amount of 5-hydroxymethyl-2-furoic acid and 2,5-furan diethanol. For example, the mixture can contain 0.35X to 0.65X moles of 5-hydroxymethyl-2-furoic acid and 0.35X to 0.65X moles of 2,5-furan diethanol, 0.40X to 0.60X moles of 5-hydroxymethyl-2-furoic acid and 0.40X to 0.60X moles of 2,5-furan diethanol, or 0.45X to 0.55X moles of 5-hydroxymethyl-2-furoic acid and 0.45X to 0.55X moles of 2,5-furan diethanol. In some embodiments, the mixture (e.g., starting material mixture) comprises 0.35X to 0.65X moles of 5-hydroxymethyl-2-furoic acid and 0.35X to 0.65X moles of 2,5-furandiethanol. In certain embodiments, the mixture (e.g., starting material mixture) comprises 0.45X to 0.55X moles of 5-hydroxymethyl-2-furoic acid and 0.45X to 0.55X moles of 2,5-furandiethanol.

[0051] The invention further provides 2,5-furandicarboxylic acid (FDCA) prepared from the methods described herein. In other words, 2,5-furandicarboxylic acid (FDCA) can be isolated from any of the methods described herein and optionally purified. In some embodiments, 2,5-furandicarboxylic acid (FDCA) is isolated and purified by extraction, dialysis, column chromatography, crystallization, recrystallization, filtration, distillation, or a combination thereof. That is, 2,5-furandicarboxylic acid (FDCA) can have any suitable purity. In some embodiments, 2,5-furandicarboxylic acid (FDCA) is crystalline.

[0052] In some embodiments, the methods described herein further include polymerizing the dicarboxylate (e.g., 2,5-furandicarboxylic acid (FDCA)) with one or more other monomers to form a polymer such as, for example, a polyester or a polyamide. That is, in some embodiments, the one or more monomers are a diol (e.g., ethylene glycol, propanediol, butanediol, or a combination thereof), a polyol, a diamine (e.g., ethylenediamine, propanediamine, butanediamine, or a combination thereof), a polyamine, or a combination thereof.

[0053] In certain embodiments, one or more other monomers include a diol (e.g., an aliphatic diol), and the polymer is a polyester. Exemplary diol monomers include aliphatic diols such as, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, and hexanediol; alicyclic diols such as, for example, 1,4-cyclohexanedimethanol; and aromatic diols such as, for example, bisphenol A.

[0054] In some embodiments, the one or more other monomers include propylene glycol and the polymer is poly(propylene 2,5-furandicarboxylate) (PPF). In other embodiments, the one or more other monomers include ethylene glycol and the polymer is poly(ethylene 2,5-furandicarboxylate) (PEF).

[0055] The invention further provides polymers prepared from the methods described herein, as well as articles of manufacture comprising the polymers. For example, the invention provides poly(propylene 2,5-furandicarboxylate) (PPF) or poly(ethylene 2,5-furandicarboxylate) (PEF) prepared by the methods described herein. The polymers prepared by the methods described herein can be used in articles for packaging applications, such as bottles, films, bags, labels, and trays.

[0056] Aspects of the disclosure

[0057] Aspects, including embodiments, of the invention described herein may be useful alone or in combination with one or more other aspects or embodiments. Without limiting the foregoing, certain non-limiting aspects of the disclosure, numbered 1 through 169, are provided below. As will be apparent to one of skill in the art upon reading this disclosure, each individually numbered aspect may be used or combined with any of the preceding or succeeding individually numbered aspects. This is intended to provide support for all such combinations of aspects, and is not limited to the combinations of aspects explicitly provided below:

[0058] (1) A process for converting an aldehyde into a mixture of an alcohol and a carboxylate, the process comprising: conducting a disproportionation reaction on a first composition comprising X moles of said aldehyde, hydroxide, catalyst, and solvent to form a second composition comprising 0.35X to 0.5X moles of said alcohol and 0.35X to 0.5X moles of said carboxylate; Including, wherein the disproportionation reaction is carried out at an initial temperature of 30° C. or less; and wherein the catalyst is: (a) Supporting material and (b) Metal A method comprising:

[0059] (2) The process of embodiment 1, wherein the disproportionation reaction is carried out at an initial temperature of room temperature.

[0060] (3) The method of embodiment 1 or embodiment 2, wherein the disproportionation reaction is carried out at atmospheric pressure.

[0061] (4) The method of any one of aspects 1-3, wherein the initial concentration of the aldehyde in the first composition is at least 1 M.

[0062] (5) The method of any one of aspects 1-4, wherein the second composition comprises 0.4X to 0.5X moles of alcohol and 0.4X to 0.5X moles of carboxylate.

[0063] (6) The method of any one of aspects 1-5, wherein the second composition comprises 0.45X to 0.5X moles of alcohol and 0.45X to 0.5X moles of carboxylate.

[0064] (7) The method of any one of aspects 1-6, wherein the aldehyde is furfural, the carboxylate is furan-2-carboxylate, and the alcohol is furfuryl alcohol.

[0065] (8) The method of any one of aspects 1-6, wherein the aldehyde is hydroxymethylfurfural, the carboxylate is 5-hydroxymethyl-2-furoic acid, and the alcohol is 2,5-furandiethanol.

[0066] (9) The method of any one of aspects 1-8, wherein the support material comprises TiO 2 , ZrO 2 , SiO 2 , Al 2 O 3 , MgO, CeO 2 , hydrotalcite, a carbon material, or a combination thereof.

[0067] (10) The method of any one of aspects 1-8, wherein the support material comprises TiO2 or a carbon material.

[0068] (11) The method of any one of aspects 1 to 10, wherein the metal comprises gold, platinum, palladium, or a combination thereof.

[0069] (12) The method of any one of aspects 1 to 10, wherein the metal comprises gold nanoparticles.

[0070] (13) The method of any one of aspects 1 to 10, wherein the metal comprises platinum nanoparticles.

[0071] (14) The method of any one of aspects 1-10, wherein the metal comprises palladium nanoparticles.

[0072] (15) The method of any one of aspects 1 to 14, wherein the metal is attached to a support material.

[0073] (16) The method of any one of aspects 1 to 15, wherein the catalyst is in the form of pellets, powder, or a combination thereof.

[0074] (17) The method of any one of aspects 1 to 16, wherein the catalyst is in the form of a powder having an average particle size of 500 μm or less.

[0075] (18) The method of any one of aspects 1 to 17, wherein the catalyst is in the form of a powder having an average particle size of 100 μm or less.

[0076] (19) The method of any one of aspects 1 to 18, wherein the hydroxide is a metal hydroxide selected from an alkali metal hydroxide, an alkaline earth metal hydroxide, and a combination thereof.

[0077] (20) The method of any one of aspects 1 to 18, wherein the hydroxide is an alkali metal hydroxide.

[0078] (21) The method of any one of aspects 1 to 18, wherein the hydroxide is cesium hydroxide.

[0079] (22) The method of any one of aspects 1 to 21, wherein the solvent comprises water.

[0080] (23) The method of any one of aspects 1 to 21, wherein the solvent is water.

[0081] (24) The method of any one of aspects 1 to 23, wherein the disproportionation reaction is carried out under batch reaction conditions.

[0082] (25) The method of any one of aspects 1 to 23, wherein the disproportionation reaction is carried out under continuous flow conditions.

[0083] (26) The method of embodiment 25, wherein the continuous flow conditions comprise (a) passing a solution comprising an aldehyde, a metal hydroxide, and a solvent through a reaction vessel containing a catalyst such that the disproportionation reaction can be carried out continuously.

[0084] (27) The process of any one of aspects 1 to 26, wherein the disproportionation reaction is carried out in a fixed bed reactor.

[0085] (28) The method of any one of aspects 1 to 27, wherein the method further comprises performing an oxidation reaction on the alcohol to convert the alcohol to a carboxylate.

[0086] (29) The method of embodiment 28, wherein the oxidation reaction is carried out under an increased partial pressure of oxygen and / or an increased temperature compared to the disproportionation reaction.

[0087] (30) The method of embodiment 28 or embodiment 29, wherein the oxidation reaction is carried out under an increased partial pressure of oxygen and an increased temperature compared to the disproportionation reaction.

[0088] (31) The method of any one of aspects 28 to 30, wherein the oxidation reaction is carried out at a temperature of 30° C. or higher.

[0089] (32) The method of any one of aspects 28 to 30, wherein the oxidation reaction is carried out at a temperature of 55°C to 100°C.

[0090] (33) The method of any one of aspects 28 to 30, wherein the oxidation reaction is carried out at a temperature of 55°C to 80°C.

[0091] (34) The method of any one of aspects 28 to 33, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 100 kPa.

[0092] (35) The method of any one of aspects 28 to 34, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 500 kPa.

[0093] (36) The method of any one of aspects 28 to 35, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 1 MPa.

[0094] (37) The method of any one of aspects 28 to 36, wherein the oxidation reaction is carried out in the presence of a hydroxide, a catalyst, and a solvent.

[0095] (38) The method of embodiment 37, wherein the hydroxide, catalyst, and solvent are the same for the disproportionation reaction and the oxidation reaction.

[0096] (39) The method of any one of aspects 28 to 38, wherein the disproportionation reaction and the oxidation reaction are carried out in the same reaction vessel.

[0097] (40) The method of any one of aspects 28 to 38, wherein the disproportionation reaction and the oxidation reaction are carried out in different reaction vessels.

[0098] (41) The method of any one of aspects 28 to 40, wherein the oxidation reaction is carried out under batch reaction conditions.

[0099] (42) The method of any one of aspects 28 to 40, wherein the oxidation reaction is carried out under continuous flow conditions.

[0100] (43) The method of embodiment 42, wherein the continuous flow conditions comprise passing a solution comprising the carboxylate, the alcohol, the metal hydroxide, and the solvent through a reaction vessel containing the catalyst such that the oxidation reaction can be carried out continuously.

[0101] (44) The method of any one of aspects 28 to 43, wherein the oxidation reaction is carried out in a trickle-bed reactor.

[0102] (45) A method for converting an aldehyde to a carboxylate, the method comprising: (i) performing a disproportionation reaction on a first composition comprising the aldehyde, a hydroxide, a catalyst, and a solvent to form a second composition comprising the carboxylate, an alcohol, the hydroxide, the catalyst, and the solvent; (ii) optionally adjusting the concentration of the carboxylate, the alcohol, the hydroxide, and / or the catalyst in the second composition; and (iii) carrying out an oxidation reaction on the second composition under an increased partial pressure of oxygen and / or an increased temperature compared to the disproportionation reaction to convert more of the alcohol to the carboxylate. Including, wherein the catalyst is: (a) Supporting material and (b) Metal A method comprising:

[0103] (46) The method of embodiment 45, wherein the oxidation reaction is carried out under an increased partial pressure of oxygen and an increased temperature compared to the disproportionation reaction.

[0104] (47) The method of embodiment 45 or embodiment 46, wherein the disproportionation reaction is carried out at an initial temperature of 30° C. or less.

[0105] (48) The method of any one of aspects 45 to 47, wherein the disproportionation reaction is carried out at an initial temperature of room temperature.

[0106] (49) The method of any one of aspects 45 to 48, wherein the disproportionation reaction is carried out at atmospheric pressure.

[0107] (50) The method of any one of aspects 45 to 49, wherein the oxidation reaction is carried out at a temperature of 30° C. or higher.

[0108] (51) The method of any one of aspects 45 to 49, wherein the oxidation reaction is carried out at a temperature of 55°C to 100°C.

[0109] (52) The method of any one of aspects 45 to 49, wherein the oxidation reaction is carried out at a temperature of 55°C to 80°C.

[0110] (53) The method of any one of aspects 45 to 52, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 100 kPa.

[0111] (54) The method of any one of aspects 45 to 52, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 500 kPa.

[0112] (55) The method of any one of aspects 45 to 52, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 1 MPa.

[0113] (56) The method of any one of aspects 45 to 55, wherein the initial concentration of the aldehyde in the first composition is at least 1 M.

[0114] (57) The method of any one of aspects 45 to 56, wherein at least 80% of the aldehyde is consumed before increasing the partial pressure of oxygen and / or the temperature.

[0115] (58) The method of any one of aspects 45 to 56, wherein at least 90% of the aldehyde is consumed before increasing the partial pressure of oxygen and / or the temperature.

[0116] (59) The method of any one of aspects 45 to 56, wherein at least 95% of the aldehyde is consumed before increasing the partial pressure of oxygen and / or the temperature.

[0117] (60) The method of any one of aspects 45 to 56, wherein at least 99% of the aldehyde is consumed before increasing the partial pressure of oxygen and / or the temperature.

[0118] (61) The method of any one of aspects 45 to 60, wherein the aldehyde is furfural, the carboxylate is furan-2-carboxylate, and the alcohol is furfuryl alcohol.

[0119] (62) The method of any one of aspects 45 to 60, wherein the aldehyde is hydroxymethylfurfural, the carboxylate is 5-hydroxymethyl-2-furoic acid, and the alcohol is 2,5-furandiethanol.

[0120] (63) The method of any one of embodiments 45-62, wherein the support material comprises TiO 2 , ZrO 2 , SiO 2 , Al 2 O 3 , MgO, CeO 2 , hydrotalcite, a carbon material, or a combination thereof.

[0121] (64) The method of any one of embodiments 45 to 62, wherein the support material comprises TiO2 or a carbon material.

[0122] (65) The method of any one of embodiments 45-64, wherein the metal comprises gold, platinum, palladium, or a combination thereof.

[0123] (66) The method of any one of embodiments 45 to 64, wherein the metal comprises gold nanoparticles.

[0124] (67) The method of any one of embodiments 45 to 64, wherein the metal comprises platinum nanoparticles.

[0125] (68) The method of any one of embodiments 45 to 64, wherein the metal comprises palladium nanoparticles.

[0126] (69) The method of any one of embodiments 45 to 68, wherein the metal is attached to a support material.

[0127] (70) The method of any one of embodiments 45 to 69, wherein the catalyst is in the form of pellets, powder, or a combination thereof.

[0128] (71) The method of any one of aspects 45 to 70, wherein the catalyst is in the form of a powder having an average particle size of 500 μm or less.

[0129] (72) The method of any one of aspects 45 to 70, wherein the catalyst is in the form of a powder having an average particle size of 100 μm or less.

[0130] (73) The method of any one of embodiments 45 to 72, wherein the hydroxide is a metal hydroxide selected from an alkali metal hydroxide, an alkaline earth metal hydroxide, and a combination thereof.

[0131] (74) The method of any one of aspects 45 to 72, wherein the hydroxide is an alkali metal hydroxide.

[0132] (75) The method of any one of aspects 45 to 72, wherein the hydroxide is cesium hydroxide.

[0133] (76) The method of any one of embodiments 45 to 75, wherein the solvent comprises water.

[0134] (77) The method of any one of aspects 45 to 75, wherein the solvent is water.

[0135] (78) The method of any one of aspects 45 to 77, wherein the disproportionation reaction and the oxidation reaction are carried out in the same reaction vessel.

[0136] (79) The method of any one of embodiments 45 to 77, wherein the disproportionation reaction and the oxidation reaction are carried out in different reaction vessels.

[0137] (80) The method of any one of aspects 45 to 79, wherein the disproportionation reaction and / or the oxidation reaction is carried out under batch reaction conditions.

[0138] (81) The method of any one of aspects 45 to 79, wherein the disproportionation reaction and / or the oxidation reaction is carried out under continuous flow conditions.

[0139] (82) The method of embodiment 81, wherein the continuous flow conditions comprise passing (a) a solution comprising an aldehyde, a metal hydroxide, and a solvent through a reaction vessel containing the catalyst, and / or (b) a solution comprising a carboxylate, an alcohol, a metal hydroxide, and a solvent through a reaction vessel containing the catalyst, such that the disproportionation reaction and / or the oxidation reaction can be carried out continuously.

[0140] (83) The method of any one of aspects 78 to 82, wherein the reaction vessel is a trickle bed reactor, a fixed bed reactor, or a combination thereof.

[0141] (84) A method for producing a carboxylate, the method comprising: carrying out an oxidation reaction of furfuryl alcohol in a composition containing a hydroxide, a catalyst, a solvent, and furfuryl alcohol; Including, wherein the carboxylate is furan-2-carboxylate; and wherein the catalyst is: (a) Supporting material and (b) Metal A method comprising:

[0142] (85) The method of embodiment 84, wherein the method comprises conducting an oxidation reaction on a mixture of furan-2-carboxylic acid and furfuryl alcohol in a composition comprising a hydroxide, a catalyst, a solvent, and the mixture of furan-2-carboxylic acid and furfuryl alcohol.

[0143] (86) The method of embodiment 85, wherein the mixture comprises 0.35X to 0.65X moles of furan-2-carboxylate and 0.35X to 0.65X moles of furfuryl alcohol.

[0144] (87) The method of embodiment 85, wherein the mixture comprises 0.45X to 0.55X moles of furan-2-carboxylate and 0.45X to 0.55X moles of furfuryl alcohol.

[0145] (88) The method of any one of embodiments 84-87, wherein the support material comprises TiO 2 , ZrO 2 , SiO 2 , Al 2 O 3 , MgO, CeO 2 , hydrotalcite, a carbon material, or a combination thereof.

[0146] (89) The method of any one of embodiments 84 to 87, wherein the support material comprises TiO2 or a carbon material.

[0147] (90) The method of any one of embodiments 84-89, wherein the metal comprises gold, platinum, palladium, or a combination thereof.

[0148] (91) The method of any one of embodiments 84 to 90, wherein the metal comprises gold nanoparticles.

[0149] (92) The method of any one of embodiments 84 to 90, wherein the metal comprises platinum nanoparticles.

[0150] (93) The method of any one of embodiments 84 to 90, wherein the metal comprises palladium nanoparticles.

[0151] (94) The method of any one of embodiments 84 to 93, wherein the metal is attached to a support material.

[0152] (95) The method of any one of embodiments 84 to 94, wherein the catalyst is in the form of pellets, powder, or a combination thereof.

[0153] (96) The method of any one of aspects 84 to 95, wherein the catalyst is in the form of a powder having an average particle size of 500 μm or less.

[0154] (97) The method of any one of aspects 84 to 96, wherein the catalyst is in the form of a powder having an average particle size of 100 μm or less.

[0155] (98) The method of any one of embodiments 84 to 97, wherein the hydroxide is a metal hydroxide selected from an alkali metal hydroxide, an alkaline earth metal hydroxide, and a combination thereof.

[0156] (99) The method of any one of embodiments 84 to 97, wherein the hydroxide is an alkali metal hydroxide.

[0157] (100) The method of any one of embodiments 84 to 97, wherein the hydroxide is cesium hydroxide.

[0158] (101) The method of any one of aspects 84 to 97, wherein the oxidation reaction is carried out in the presence of a metal hydroxide selected from an alkali metal hydroxide, an alkaline earth metal hydroxide, and a combination thereof, a carbon material, and a metal comprising gold, platinum, palladium, or a combination thereof.

[0159] (102) The method of any one of embodiments 84 to 101, wherein the solvent comprises water.

[0160] (103) The method of any one of embodiments 84 to 101, wherein the solvent is water.

[0161] (104) The method of any one of aspects 84 to 103, wherein the oxidation reaction is carried out at a temperature of 30° C. or higher.

[0162] (105) The method of any one of aspects 84 to 103, wherein the oxidation reaction is carried out at a temperature of 55°C to 100°C.

[0163] (106) The method of any one of aspects 84 to 103, wherein the oxidation reaction is carried out at a temperature of 55°C to 80°C.

[0164] (107) The method of any one of aspects 84 to 106, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 100 kPa.

[0165] (108) The method of any one of aspects 84 to 106, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 500 kPa.

[0166] (109) The method of any one of aspects 84 to 106, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 1 MPa.

[0167] (110) The method of any one of embodiments 84 to 109, wherein the oxidation reaction is carried out under batch reaction conditions.

[0168] (111) The method of any one of embodiments 84 to 109, wherein the oxidation reaction is carried out under continuous flow conditions.

[0169] (112) The method of embodiment 111, wherein the continuous flow conditions include passing a solution containing the hydroxide, the solvent, and a mixture of furan-2-carboxylate and furfuryl alcohol through a reaction vessel containing a catalyst such that the oxidation reaction can be carried out continuously.

[0170] (113) The method of any one of embodiments 84 to 112, wherein the oxidation reaction is carried out in a trickle-bed reactor.

[0171] (114) The method of any one of embodiments 1 to 113, wherein the method further comprises converting the carboxylate to a dicarboxylate.

[0172] (115) The method of embodiment 114, wherein the carboxylate is converted to a dicarboxylate by performing a carboxylation reaction on the carboxylate with (i) a carbonate in the presence of carbon dioxide or (ii) a hydroxide in the presence of carbon dioxide to form the dicarboxylate.

[0173] (116) The method of embodiment 114 or embodiment 115, wherein the dicarboxylate is 2,5-furandicarboxylic acid.

[0174] (117) The method of embodiment 114 or embodiment 115, wherein the carbonate is a metal carbonate selected from alkali metal carbonates, alkaline earth metal carbonates, and combinations thereof.

[0175] (118) The method of embodiment 114 or embodiment 115, wherein the carbonate is an alkali metal carbonate.

[0176] (119) The method of embodiment 114 or embodiment 115, wherein the carbonate is cesium carbonate.

[0177] (120) The method of any one of aspects 28 to 83, wherein the aldehyde is hydroxymethylfurfural and the oxidation reaction converts a mixture of 5-hydroxymethyl-2-furoic acid and 2,5-furandiimethanol directly to a dicarboxylate, wherein the dicarboxylate is 2,5-furandicarboxylic acid.

[0178] (121) The method of embodiment 120, wherein the oxidation reaction is carried out in the presence of a metal hydroxide selected from alkali metal hydroxides, alkaline earth metal hydroxides, and combinations thereof, a carbon material, and a metal comprising gold, platinum, palladium, or a combination thereof.

[0179] (122) The method of embodiment 121, wherein the metal comprises gold nanoparticles.

[0180] (123) The method of embodiment 121, wherein the metal comprises platinum nanoparticles.

[0181] (124) The method of embodiment 121, wherein the metal comprises palladium nanoparticles.

[0182] (125) The method of any one of embodiments 121 to 124, wherein the hydroxide is an alkali metal hydroxide.

[0183] (126) The method of embodiment 125, wherein the hydroxide is cesium hydroxide.

[0184] (127) A method for producing a dicarboxylate, the method comprising: The oxidation reaction of 2,5-furan diethanol is carried out in a composition containing a hydroxide, a catalyst, a solvent, and 2,5-furan diethanol. Including, wherein the dicarboxylate is 2,5-furandicarboxylic acid; and wherein the catalyst is: (a) Supporting material and (b) Metal A method comprising:

[0185] (128) The method of embodiment 127, wherein the method comprises conducting an oxidation reaction on a mixture of 5-hydroxymethyl-2-furoic acid and 2,5-furandiethanol in a composition comprising a hydroxide, a catalyst, a solvent, and the mixture of 5-hydroxymethyl-2-furoic acid and 2,5-furandiethanol.

[0186] (129) The method of embodiment 128, wherein the mixture comprises 0.35X to 0.65X moles of 5-hydroxymethyl-2-furoic acid and 0.35X to 0.65X moles of 2,5-furandiethanol.

[0187] (130) The method of embodiment 128, wherein the mixture comprises 0.45X to 0.55X moles of 5-hydroxymethyl-2-furoic acid and 0.45X to 0.55X moles of 2,5-furandiethanol.

[0188] (131) The method of any one of embodiments 127-130, wherein the support material comprises TiO 2 , ZrO 2 , SiO 2 , Al 2 O 3 , MgO, CeO 2 , hydrotalcite, a carbon material, or a combination thereof.

[0189] (132) The method of any one of embodiments 127-130, wherein the support material comprises TiO2 or a carbon material.

[0190] (133) The method of any one of embodiments 127-132, wherein the metal comprises gold, platinum, palladium, or a combination thereof.

[0191] (134) The method of any one of embodiments 127 to 133, wherein the metal comprises gold nanoparticles.

[0192] (135) The method of any one of embodiments 127 to 133, wherein the metal comprises platinum nanoparticles.

[0193] (136) The method of any one of embodiments 127 to 133, wherein the metal comprises palladium nanoparticles.

[0194] (137) The method of any one of embodiments 127 to 136, wherein the metal is attached to a support material.

[0195] (138) The method of any one of embodiments 127 to 137, wherein the catalyst is in the form of pellets, powder, or a combination thereof.

[0196] (139) The method of any one of embodiments 127 to 138, wherein the catalyst is in the form of a powder having an average particle size of 500 μm or less.

[0197] (140) The method of any one of embodiments 127 to 139, wherein the catalyst is in the form of a powder having an average particle size of 100 μm or less.

[0198] (141) The method of any one of embodiments 127 to 140, wherein the hydroxide is a metal hydroxide selected from an alkali metal hydroxide, an alkaline earth metal hydroxide, and a combination thereof.

[0199] (142) The method of any one of embodiments 127 to 140, wherein the hydroxide is an alkali metal hydroxide.

[0200] (143) The method of any one of embodiments 127 to 140, wherein the hydroxide is cesium hydroxide.

[0201] (144) The method of any one of embodiments 127 to 140, wherein the oxidation reaction is carried out in the presence of a metal hydroxide selected from alkali metal hydroxides, alkaline earth metal hydroxides, and combinations thereof, a carbon material, and a metal comprising gold, platinum, palladium, or a combination thereof.

[0202] (145) The method of any one of embodiments 127 to 144, wherein the solvent comprises water.

[0203] (146) The method of any one of embodiments 127 to 144, wherein the solvent is water.

[0204] (147) The method of any one of embodiments 127 to 146, wherein the oxidation reaction is carried out at a temperature of 30°C or higher.

[0205] (148) The method of any one of embodiments 127 to 146, wherein the oxidation reaction is carried out at a temperature of 55°C to 100°C.

[0206] (149) The method of any one of embodiments 127 to 146, wherein the oxidation reaction is carried out at a temperature of 55°C to 80°C.

[0207] (150) The method of any one of embodiments 127 to 149, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 100 kPa.

[0208] (151) The method of any one of embodiments 127 to 149, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 500 kPa.

[0209] (152) The method of any one of embodiments 127 to 149, wherein the oxidation reaction is carried out under an oxygen partial pressure of at least 1 MPa.

[0210] (153) The method of any one of embodiments 127 to 152, wherein the oxidation reaction is carried out under batch reaction conditions.

[0211] (154) The method of any one of embodiments 127 to 152, wherein the oxidation reaction is carried out under continuous flow conditions.

[0212] (155) The method of embodiment 154, wherein the continuous flow conditions include passing a solution containing the hydroxide, the solvent, and a mixture of 5-hydroxymethyl-2-furoic acid and 2,5-furandiethanol through a reaction vessel containing a catalyst so that the oxidation reaction can be carried out continuously.

[0213] (156) The method of any one of embodiments 127 to 155, wherein the oxidation reaction is carried out in a trickle-bed reactor.

[0214] (157) The method of any one of embodiments 114 to 156, wherein the method further comprises purifying the dicarboxylate.

[0215] (158) The method of any one of embodiments 114 to 157, wherein the method further comprises polymerizing the dicarboxylate with one or more other monomers to form a polymer.

[0216] (159) The method of embodiment 158, wherein the one or more other monomers comprise a diol and the polymer is a polyester.

[0217] (160) The method of embodiment 158, wherein the one or more other monomers include propylene glycol and the polymer is poly(propylene 2,5-furandicarboxylate) (PPF).

[0218] (161) The method of embodiment 158, wherein the one or more other monomers include ethylene glycol and the polymer is poly(ethylene 2,5-furandicarboxylate) (PEF).

[0219] (162) A polymer prepared by the method of any one of embodiments 158 to 161.

[0220] (163) A product comprising the polymer of embodiment 162.

[0221] (164) 2,5-furandicarboxylic acid prepared by the method of any one of embodiments 1 to 157.

[0222] (165) The 2,5-furandicarboxylic acid of embodiment 164, wherein the 2,5-furandicarboxylic acid is crystalline.

[0223] (166) A polyester comprising a diol and 2,5-furandicarboxylic acid of any one of embodiments 164 or 165.

[0224] (167) The method of embodiment 166, wherein the diol is propylene glycol and the polymer is poly(propylene 2,5-furandicarboxylate) (PPF).

[0225] (168) The method of embodiment 166, wherein the diol is ethylene glycol and the polymer is poly(ethylene 2,5-furandicarboxylate) (PEF).

[0226] (169) A product comprising the polyester of any one of embodiments 166 to 168. [Example]

[0227] The following examples further illustrate the invention but, of course, should not be construed as in any way limiting its scope.

[0228] Example 1 This example provides an analytical method for monitoring the outcome of the furfural oxidation reaction by high performance liquid chromatography (HPLC).

[0229] The analysis was performed using an AGILENT HPLC column equipped with a Metacarb 67H column and a diode array detector. TM The analysis was performed on a 1200 HPLC system. As shown in Figure 4D, the Metacarb 67H column provided optimal separation between furfural, furoate, and furfuryl alcohol, allowing for their quantification. Calibration and quantification were performed using a detection wavelength of 210 nm, and the calibration curves for furfural, furoate, and furfuryl alcohol are shown in Figures 4A-4C, respectively.

[0230] Analysis of samples taken from furfural oxidation was complicated by furfural undergoing Cannizzaro disproportionation and decomposition in the presence of concentrated base; accurate assessment of reactant and product concentrations at the time of sampling required that analytical samples be quenched to minimize any furfural consumption that occurred between sampling and analysis.

[0231] To demonstrate the stability of furfural in aqueous solutions containing CsOH, samples were prepared with (a) initial concentrations of 1.0 M furfural and 0.5 M cesium hydroxide (CsOH), (b) a 100-fold dilution of the sample from (a) with water, and (c) a 100-fold dilution of the sample from (a) with triethylammonium acetate (TEA(OAc)) buffer solution (1.0 M, pH 7). The dilutions with water and TEA(OAc) buffer were performed immediately after mixing the concentrated solution (a). The results of the stability evaluation are shown in Table 1.

[0232] [Table 1]

[0233] As is evident from the results shown in Table 1, the concentrated sample with an initial concentration of 1.0 M furfural and 0.5 M CsOH lost 73% of its furfural over a one-day period. Diluting the concentrated sample 100-fold with water attenuated the reactivity, but gradual consumption of furfural was still observed over the course of several days. Furfural stability was further improved by diluting the concentrated sample 100-fold with TEA(OAc) buffer.

[0234] As a result, the standard sampling procedure for monitoring furfural oxidation reactions used in the examples described herein involved immediate approximately 100-fold dilution in 1.0 M TEA(OAc) solution. The buffered, diluted samples were then directly subjected to HPLC analysis to assess reaction yield at the time of sampling / quenching.

[0235] Example 2 This example demonstrates the reactivity of furfural under alkaline conditions at process-relevant concentrations. Possible furfural disproportionation and decomposition products are summarized in Scheme 1.

[0236] [ka]

[0237] Small-scale reactions were performed to evaluate the rates of furfural disproportionation (i.e., the Cannizzaro reaction) and competing furfural degradation reactions under the following conditions: (a) 1.0 M furfural and 1.0 M CsOH, (b) 1.0 M furfural and 0.5 M CsOH, (c) 0.75 M furfural and 0.75 M CsOH, (d) 1.0 M furfural and 0.5 M CsCO, and (e) 1.0 M furfural and 1.0 M CsCO. Under each of the aforementioned conditions, furfural was added to a solution of base in water to obtain a total solution volume of approximately 10 mL. The resulting mixture was first shaken to mix and then shaken again, after which it was sampled at set time points by removing an aliquot of the solution and quenching it with dilution in TEA(OAc) buffer. The diluted samples were subjected to HPLC analysis to evaluate the amount of consumed furfural and the amount of Cannizzaro (disproportionation) products produced. The results for (a) to (c) are shown in Figures 5A to 5C, respectively, and the results for (d) and (e) are shown in Figure 5D.

[0238] As is evident from the results shown in Figures 5A-5C, when CsOH was used as the base, consumption of furfural and production of Cannizzaro (disproportionation) products were observed within the first 20 minutes of mixing at room temperature. Degradation products were quantified by the difference between the amount of furfural consumed and the amount of Cannizzaro products produced. Figures 5A-5C show that the rate of furfural consumption increased with CsOH concentration. As demonstrated by Figure 5A, 1.0 M furfural and 1.0 M CsOH resulted in a 40% consumption of furfural after 20 minutes, with 30% converted to Cannizzaro (disproportionation) products and 10% lost to degradation products, which were easily observed by a rapid darkening of the solution color. As demonstrated by Figure 5B, 1.0 M furfural and 0.5 M CsOH resulted in only 10% consumption of furfural after 20 minutes, with 7% converted to Cannizzaro (disproportionation) products and 3% lost to degradation products. As demonstrated by Figure 5C, 0.75 M furfural and 0.75 M CsOH resulted in 25% consumption of furfural after 20 minutes, with 23% converted to Cannizzaro (disproportionation) products and 2% lost to degradation products. That is, while Cannizzaro (disproportionation) was the predominant pathway, the formation of degradation products was consistently observed.

[0239] As is evident from the results shown in Figures 5D and 5E, no Cannizzaro products were observed when cesium carbonate (Cs2CO3) base was used instead of CsOH. As demonstrated by Figure 5D, 1.0 M furfural and 0.5 M Cs2CO3 resulted in limited degradation, while Figure 5E shows that 1.0 M furfural and 1.0 M Cs2CO3 resulted in approximately 40% furfural degradation after 20 minutes.

[0240] These results suggest that decomposition by oligomerization or polymerization occurs in aqueous solutions containing Brønsted bases (e.g., CO 2-), indicating that hydroxide is required to promote the Cannizzaro disproportionation reaction. Without wishing to be bound by any particular theory, - The formation of a tetrahedral intermediate via attack is believed to be the key step in the disproportionation reaction. A putative mechanism for the Cannizzaro disproportionation reaction is provided in Scheme 2.

[0241] [ka]

[0242] Example 3 This example demonstrates the effect on furfural stability exhibited by the presence of a catalyst.

[0243] A catalyst containing 1 wt % Au nanoparticles on TiO2 extrudates (Au / TiO2, commercially available from Strem Chemicals, Inc.) was ground with a mortar and pestle before use.

[0244] Small-scale reactions were performed to evaluate the rates of furfural disproportionation (i.e., the Cannizzaro reaction) and the competing furfural degradation reaction using a reaction mixture containing 1.0 M furfural, 1.0 M CsOH, 0.3 mol% Au loading relative to furfural, and water to make a solution volume of 10 mL. The resulting mixture was first shaken to mix and then shaken again, after which it was sampled at set time points by removing an aliquot of the solution and quenching it with dilution in TEA(OAc) buffer. The diluted samples were subjected to HPLC analysis to assess the amount of furfural consumed and the Cannizzaro (disproportionation) products produced. The results are shown in Figure 6A.

[0245] As is evident from the results shown in Figure 6A, the Au / TiO catalyst greatly accelerated the Cannizzaro disproportionation reaction, such that essentially quantitative (approximately 97%) production of the Cannizzaro product was observed after only 10 min.

[0246] To confirm that the rate acceleration was due to the Au / TiO catalyst, similar reactions were performed (a) without any catalyst, (b) in the presence of Au / TiO catalyst, (c) in the presence of TiO, and (d) in the presence of AlO. The results are shown in Figure 6B. As is evident from the results shown in Figure 6B, rate acceleration was not observed without any catalyst, in the presence of TiO, or in the presence of AlO. These results indicate that the Au / TiO accelerated the Cannizzaro disproportionation reaction.

[0247] To further test the effects of hydroxide base and Au / TiO catalyst on the Cannizzaro disproportionation reaction, similar reactions were carried out using reduced amounts of hydroxide base (0.5 M) or Au / TiO catalyst (0.15 mol %). The results are shown in Figure 6C. As is evident from the results shown in Figure 6C, the rate of the reaction decreased when the amount of hydroxide base or Au / TiO catalyst was reduced; however, the consumption of furfural remained significantly faster than in the uncatalyzed reaction.

[0248] Given the previous results demonstrating that the Au / TiO catalyst greatly accelerated the Cannizzaro disproportionation reaction and minimized competing furfural degradation pathways, the stability of the Cannizzaro product in the presence of excess base was investigated. Samples were prepared containing 0.5 M concentrations of each of CsOH, cesium furoate, and furfuryl alcohol, both with and without catalyst. In both cases, 100% recovery of both furoate and furfuryl alcohol was observed over 24 hours of mixing at room temperature and after heating the mixture to 50 °C for 1 hour. Thus, the Au / TiO catalyst accelerates the consumption of furfural to produce more stable reaction products (i.e., furoate and furfuryl alcohol), thereby minimizing aldehyde degradation products.

[0249] Example 4 This example demonstrates that Au catalysts prepared using oxide support materials of various compositions and morphologies are active in promoting the Cannizzaro (disproportionation) reaction of furfural to form furoate and furfuryl alcohol.

[0250] Catalysts were prepared by incipient wetness impregnation of KAuO precursor solutions into commercially available catalyst support materials from various suppliers (Tronox Inc., Evonik Industries, Saint-Gobain NorPro, and Daiichi Kigenso Kagaku Kogyo Co., Ltd. (DKKK)) as shown in Table 2. For support materials supplied as pellets, the material was ground to a fine powder before the impregnation step. Impregnation was followed by a gas-phase reduction to form Au nanoparticles dispersed on the oxide support.

[0251] The catalysts were used in small-scale furfural (FF) disproportionation reactions to form furoate (FA) and furfuryl alcohol (FOH) according to the procedure and reaction conditions described in Example 3. The mass of catalyst used was kept constant between experiments and corresponded to a loading of 0.3 mol % Au relative to furfural for each 1 wt % Au loading on the catalyst support. The results of the reactions using selected catalysts are shown in Table 2, in comparison with those obtained using a commercially available Au / TiO catalyst purchased from Strem Chemicals, Inc.

[0252] [Table 2]

[0253] As is evident from the results shown in Table 2, gold catalysts with high activity for promoting the Cannizzaro (disproportionation) reaction of furfural can be prepared on a variety of TiO2- and ZrO2-based oxide support materials.

[0254] Example 5 This example provides the results of furfural (FF) disproportionation and oxidation to form furfuryl alcohol (FOH) and furoate (FA) under batch conditions in a stirred tank reactor.

[0255] The reaction was carried out in a 600 mL stainless steel Parr reactor with the reactor configuration shown in Figure 2. The reactor was first charged with Au / TiO catalyst (18.45 g, commercially available from Strem Chemicals, Inc.), either in pellet form or as a powder obtained by grinding with a mortar and pestle. Next, water was added to the reactor, followed by cesium hydroxide as a solid or as a 50 wt% solution, and then furfural (30 g). The reactor was sealed immediately after the addition of furfural. The sealed Parr reactor was placed on a reactor stand, and airflow was immediately initiated with the backpressure regulator set to the pressure provided in Table 3. Once the set pressure was reached at a flow rate of 1.3 standard liters per minute, the contents of the reactor were stirred at a speed of 1000 rpm and heated to the temperature provided in Table 3. At different time points, aliquots of the product mixture were collected from the sampling port of the Parr reactor after removing the dead volume. Each aliquot was filtered using a 1 μm PTFE syringe filter to remove any suspended catalyst powder, and 10 μL of the filtered aliquot was added to a pre-mixed TEA(OAc) buffer solution to quench for HPLC analysis. The aliquot corresponding to time t=0 was the first aliquot taken immediately after the reactor reached the set temperature. The time to increase the temperature to the set point was generally approximately 20 minutes, and thus the yield at time t=0 reflects the Cannizzaro and oxidation reactions that occurred during the temperature increase.

[0256] A series of reactions was carried out using a 1:1 furfural:CsOH stoichiometry at a 30 g scale (furfural) with an initial furfural concentration of 1.1 M, under an air flow of 1.3 standard liters per minute and an overhead stirrer operating at 1000 revolutions per minute, using a 0.3 mol% Au / TiO catalyst loading. Pressure, temperature, and catalyst pretreatment were varied between experiments, as shown in Table 3, and the results are shown in Table 3.

[0257] [Table 3]

[0258] As is evident from the results shown in Table 3, Reaction 1 produced 44% and 46% yields of furfuryl alcohol and furoate, respectively, at t=0, consistent with predominant Cannizzaro (disproportionation) reactivity during the temperature increase. However, over the course of the next 4 hours, furfuryl alcohol was slowly oxidized to furoate, as evidenced by the slow decrease in furfuryl alcohol and the increase in furoate yield. This result indicates that the Cannizzaro reaction occurs almost immediately, followed by the slow oxidation of furfuryl alcohol.

[0259] Reaction 2 repeated all of the parameters of Reaction 1, except that the catalyst was crushed with a mortar and pestle before carrying out the reaction. As is evident from the results shown in Table 3, crushing the catalyst before carrying out the reaction resulted in a faster reaction and increased the yield of furoate. Reactions 3-7 show that increasing the temperature and / or pressure also enhanced the rate of furoate production; however, increasing the temperature and / or pressure did not have a significant effect on the overall furoate yield.

[0260] To test whether furfural oxidation could be carried out with CsCO instead of CsOH, two experiments were performed using CsCO. These reactions were carried out at the same initial concentration (i.e., 1.1 M) and with either a 1:1 or 1:2 furfural:CsCO stoichiometry. The reactions were carried out at 100°C under 1100 psi of air (7584 kPa) with stirring at 1000 revolutions per minute. Both reactions produced essentially no furfuryl alcohol (1% yield) and a modest amount of furoate (23% yield). The minimal amount of furfuryl alcohol confirms that no Cannizzaro (disproportionation) reaction occurs in the presence of CsCO. The modest yield of furoate indicates that it is possible to oxidize furfural with Cs2CO3 as a base at relatively high temperatures, but the inefficiency of the reaction suggests that oxidation of furfuryl alcohol with Cs2CO3 is unlikely at lower temperatures.

[0261] Example 6 This example demonstrates that the Cannizzaro (disproportionation) reaction products, i.e., furfuryl alcohol and furoate, can be easily converted to more furoate in a batch process using a Au / TiO catalyst, as shown in Scheme 3.

[0262] [ka]

[0263] Parallel 25 mL batch reactors in a Biotage system were charged with 5 mL of an aqueous solution containing 2.5 mmol furoate, 2.5 mmol furfuryl alcohol, and CsOH, resulting in 0.5 M furoate and furfuryl alcohol solutions, respectively. This solution corresponds to the product of a quantitative Cannizzaro reaction starting with 1 M furfural. Au / TiO catalyst (commercially available from Strem Chemicals, Inc.) was added at a loading of either 0.3 mol% or 0.6 mol%, and the reactors were sealed, pressurized with 225 psi O (1551 kPa O), and stirred at 400 revolutions per minute at either 50°C or 60°C for 1 to 3 hours. The results are shown in Table 4.

[0264] [Table 4]

[0265] As is evident from the results shown in Table 4, all reactions showed substantial conversion of furfuryl alcohol to furoate, demonstrating that the Au / TiO2-catalyzed oxidation of furfuryl alcohol works. The best conversion yield was obtained after 3 hours when the reaction was carried out at 60 °C with 0.6 mol% Au / TiO2 and 1.2 molar equivalents of CsOH, in which 93% of the furfuryl alcohol was oxidized to furoate.

[0266] Example 7 This example demonstrates that Au catalysts prepared using oxide support materials of various compositions and morphologies are active in promoting the oxidation of the Cannizzaro (disproportionation) reaction products, i.e., furfuryl alcohol and furoate, to more furoate.

[0267] Catalysts were prepared by incipient wetness impregnation of KAuO precursor solutions into two commercially available catalyst support materials: anatase TiO pellets (Catalyst A) supplied by Saint-Gobain NorPro, and 14% Y2O3-ZrO2 powder (Catalyst B) supplied by. For the TiO2 support supplied as pellets, the material was ground to a fine powder before the impregnation step. Impregnation was followed by a gas-phase reduction to form dispersed Au nanoparticles on the oxide support (2 wt% Au loading).

[0268] The two prepared catalysts were used in batch oxidation reactions to compare their activity with that of a 1% Au / TiO pellet catalyst purchased from Strem Chemicals, Inc., which was crushed before use. The reactions were carried out in a sealed, stainless steel, 1 L Parr reactor. In each case, a PTFE reactor liner was charged with the solid catalyst and an aqueous solution of 0.5 M in furoate, 0.5 M in furfuryl alcohol, and 0.6 M in CsOH, corresponding to the products of a quantitative Cannizzaro reaction starting with 1 M furfural and 1.1 molar equivalents of CsOH base. The catalyst was added at either a 0.6 mol% or 1.2 mol% Au loading, as shown in Table 5. The liner was then inserted into the vessel, and the reactor was sealed, pressurized with 48 bar of air (960 kPa O), and the contents were stirred at 600 revolutions per minute. The reactor was heated to a temperature of 60°C and held for 1 hour. After 1 hour had elapsed, the pressurized gas in the reactor was released, and the reactor was resealed and repressurized with 48 bar of air (960 kPa O). The reactor was held at 60°C for an additional 2 hours, after which it was cooled to room temperature, the pressure was released, the stirring was stopped, and a sample of the liquid product was taken for analysis by HPLC. The results of these reactions are shown in Table 5.

[0269] [Table 5]

[0270] As is evident from the results shown in Table 5, both catalysts A and B exhibit high activity for the conversion of furfuryl alcohol to additional furoate in the furfural Cannizzaro (disproportionation) reaction product mixture, similar to that of the commercial Au / TiO2 catalyst.

[0271] Example 8 This example demonstrates that the Cannizzaro (disproportionation) reaction products, i.e., furfuryl alcohol and furoate, can be converted to more furoate using a Au / TiO2 catalyst in a continuous reactor.

[0272] Aqueous solutions of 0.6 M in furoate, 0.6 M in furfuryl alcohol, and 0.72 M in CsOH were fed into a multichannel trickle-bed reactor system, as shown in Figure 7. The feedstock corresponded to the products of a quantitative Cannizzaro reaction starting with 1.2 M furfural and 1.12 molar equivalents of CsOH base. Pressurized synthetic air was fed into the reactor in a coflow orientation along with the liquid feedstock. The reactor channels were loaded with varying amounts of Au / TiO (commercially available from Strem Chemicals, Inc.) to vary the liquid hourly space velocity (LHSV) of the reaction, which was carried out in multiple channels at the same liquid flow rate. Online monitoring of the reaction was performed by gas chromatography (GC) analysis of the off-gas from each reactor channel to assess O2 depletion from the synthetic air stream. The furoate yield and starting material conversion over time in each reactor channel were determined by offline HPLC analysis of liquid samples taken at regular intervals from the product stream.

[0273] After initial screening of reaction conditions (pressure, temperature, and liquid and gas feed flow rates), 12 of the 16 reactor channels were loaded with crushed and sieved Au / TiO catalyst (125–250 μm particle size fraction) in amounts ranging from 1.2 to 2.5 g. Reactions were initiated to test the activity and stability of continuous catalytic oxidation over approximately one week of time-on-stream (TOS) using a liquid feed rate of 1.5 mL per minute (93.75 μL per channel per minute), a temperature of 60 °C, synthetic air at 30 bar pressure (600 kPa partial pressure of O), and an air flow rate of 9 L per hour (corresponding to 1.5 molar equivalents of O relative to the furfuryl alcohol in the feed solution). For the catalyst loadings used, the liquid flow rates ranged from 2.25 to 4.75 h. -1 This corresponded to LHSV values ​​in the range of 0.01 to 0.01. The results of this test are shown in Figure 8.

[0274] As is evident from the results shown in Figure 8, furfuryl alcohol in a liquid feedstock can be continuously converted to furoate in a catalytic oxidation reaction carried out in a trickle-bed reactor. The furoate yield varied slightly depending on the LHSV, with higher yields being obtained at lower LHSV values ​​(i.e., longer catalyst contact times). An initial deactivation period of the Au / TiO catalyst was observed over the first 1.5–2 days of TOS, while the furoate yield (relative to furfuryl alcohol present in the feedstock) eventually stabilized to values ​​in the range of 27–47% and remained in this range for the duration of the experiment. In a theoretical process combining an initial furfural Cannizzaro (disproportionation) reaction and subsequent oxidation of the Cannizzaro product, these yields correspond to 63–74% relative to furfural.

[0275] Example 9 This example demonstrates that the Cannizzaro (disproportionation) reaction products, i.e., 5-hydroxymethyl-2-furoic acid (HMFCA) and 2,5-furandiethanol (DHMF), can be prepared from hydroxymethylfurfural (HMF) using the method of the invention, as shown in Scheme 4.

[0276] [ka]

[0277] Laboratory-scale reactions were carried out on aqueous solutions (10 mL) containing hydroxymethylfurfural (HMF) (1 M) and hydroxide (MOH) (1 M) at room temperature using the conditions shown in Table 6. Au / TiO catalyst (commercially available from Strem Chemicals, Inc.) was added to the aqueous solution, and the resulting mixture was mixed by continuous shaking and quenched after the specified time by dilution in TEA(OAc) buffer. The diluted samples were subjected to HPLC analysis to assess the amount of HMF consumed and the amount of Cannizzaro (disproportionation) product produced. The results are shown in Table 6.

[0278] [Table 6]

[0279] As evident from the results shown in Table 6, Au / TiO effectively promotes the Cannizzaro conversion of hydroxymethylfurfural (HMF) to 0.5 moles of 5-hydroxymethyl-2-furoic acid (HMFCA) and 0.5 moles of 2,5-furandiethanol (DHMF) within 10 minutes in quantitative yield (i.e., without any recovery of HMF). Table 6 further demonstrates that the Cannizzaro products, i.e., 5-hydroxymethyl-2-furoic acid (HMFCA) and 2,5-furandiethanol (DHMF), are stable to the reaction conditions for at least 2 days.

[0280] In contrast, Table 6 shows that in the absence of an Au / TiO2 catalyst, HMF exposed to cesium hydroxide (1 M) decomposed completely in 5 days with only a 45% combined yield, and that in the absence of an Au / TiO2 catalyst, HMF exposed to sodium hydroxide (1 M) provided only a 3% combined yield after 10 days.

[0281] These results indicate that the Cannizzaro (disproportionation) reaction of hydroxymethylfurfural (HMF) was rapid and provided a stable mixture of 5-hydroxymethyl-2-furoic acid (HMFCA) and 2,5-furandiethanol (DHMF) while avoiding undesired decomposition pathways.

[0282] Example 10 This example demonstrates that the Cannizzaro (disproportionation) reaction products, i.e., 5-hydroxymethyl-2-furoic acid (HMFCA) and 2,5-furandiimethanol (DHMF), can be readily converted to furan-2,5-dicarboxylic acid (FDCA) using the method of the invention, as shown in Scheme 5.

[0283] [ka]

[0284] A laboratory-scale Cannizzaro (disproportionation) reaction was carried out on an aqueous solution (10 mL) containing hydroxymethylfurfural (HMF) (1 M) and hydroxide (MOH) (2.4 M), as described in Example 9. Upon completion of the Cannizzaro (disproportionation) reaction, the Au / TiO catalyst was removed by filtration, and fresh catalyst, as described in Table 7, was added. The oxidation reaction was then carried out in a sealed vessel, pressurized with 15.5 bar O (1550 kPa O), and stirred at 1200 revolutions per minute at 60°C for 1 hour. The oxidized sample was subjected to HPLC analysis to assess the amount of FDCA produced. The results are shown in Table 7.

[0285] [Table 7]

[0286] As is evident from the results shown in Table 7, despite the number of potential oxidation products (see Scheme 5), only two products (i.e., 5-hydroxymethyl-2-furoic acid (HMFCA) and furan-2,5-dicarboxylic acid (FDCA)) were detected from the oxidation of the Cannizzaro reaction product of HMF. Table 7 also shows that both an Au / TiO catalyst (commercially available from Strem Chemicals, Inc.) and a Pt / C catalyst (commercially available from Evonik Industries) can convert the Cannizzaro reaction product of HMF to furan-2,5-dicarboxylic acid (FDCA), with Pt / C converting the Cannizzaro reaction product of HMF in greater than 85% yield.

[0287] All references, including publications, patent applications, and patents, cited in this specification are herein incorporated by reference to the same extent as if each reference was individually and specifically indicated to be incorporated by reference and was set forth in its entirety herein.

[0288] Use of the terms "a," "an," "the," "at least one," and similar referents in the context of describing the invention (particularly in the context of the claims below) should be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Use of the term "at least one" followed by a list of one or more items (e.g., "at least one of A and B") should be construed to mean one item (A or B) selected from the listed items or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" should be construed as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise noted. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of individually referring to each separate value within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually set forth herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples or exemplary terminology (e.g., "such as") provided herein is intended merely to better clarify the invention and does not impose limitations on the scope of the invention unless otherwise stated in the claims. No terminology in the specification should be construed as indicating any element not recited in the claims as essential to the practice of the invention.

[0289] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those skilled in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as necessary, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Furthermore, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or clearly contradicted by context.

Claims

1. 1. A process for converting an aldehyde into a mixture of an alcohol and a carboxylate, the process comprising: conducting a disproportionation reaction on a first composition comprising X moles of said aldehyde, hydroxide, catalyst, and solvent to form a second composition comprising 0.35X to 0.5X moles of said alcohol and 0.35X to 0.5X moles of said carboxylate; Including, wherein the disproportionation reaction is carried out at an initial temperature of 30° C. or less; and wherein the catalyst is: (a) a support material; and (b) Metal A method comprising:

2. 2. The method of claim 1, wherein the aldehyde is furfural, the carboxylate is furan-2-carboxylate, and the alcohol is furfuryl alcohol.

3. 2. The method of claim 1, wherein the aldehyde is hydroxymethylfurfural, the carboxylate is 5-hydroxymethyl-2-furoic acid, and the alcohol is 2,5-furandiethanol.

4. 1. A method for converting an aldehyde to a carboxylate, the method comprising: (i) performing a disproportionation reaction on a first composition comprising the aldehyde, a hydroxide, a catalyst, and a solvent to form a second composition comprising the carboxylate, an alcohol, the hydroxide, the catalyst, and the solvent; (ii) optionally adjusting the concentration of the carboxylate, the alcohol, the hydroxide, and / or the catalyst in the second composition; and (iii) carrying out an oxidation reaction on the second composition under an increased partial pressure of oxygen and / or an increased temperature compared to the disproportionation reaction to convert more of the alcohol to the carboxylate. Including, wherein the catalyst is: (a) a support material; and (b) Metal A method comprising:

5. 5. The method of claim 4, wherein said aldehyde is furfural, said carboxylate is furan-2-carboxylate, and said alcohol is furfuryl alcohol.

6. 5. The method of claim 4, wherein the aldehyde is hydroxymethylfurfural, the carboxylate is 5-hydroxymethyl-2-furoic acid, and the alcohol is 2,5-furandiethanol.

7. 1. A method for producing a carboxylate, the method comprising: carrying out an oxidation reaction of furfuryl alcohol in a composition containing a hydroxide, a catalyst, a solvent, and furfuryl alcohol; Including, wherein the carboxylate is furan-2-carboxylate; and wherein the catalyst is: (a) a support material; and (b) Metal A method comprising:

8. 8. The method of claim 7, wherein the method comprises carrying out the oxidation reaction on a mixture of furan-2-carboxylate and furfuryl alcohol in a composition comprising a hydroxide, a catalyst, a solvent, and the mixture of furan-2-carboxylate and furfuryl alcohol.

9. 9. The method of claim 8, wherein the mixture comprises 0.35X to 0.65X moles of furan-2-carboxylate and 0.35X to 0.65X moles of furfuryl alcohol.

10. 10. The method of any one of claims 1 to 9, wherein the method further comprises converting the carboxylate to a dicarboxylate.

11. 1. A method for producing a dicarboxylate, the method comprising: The oxidation reaction of 2,5-furan diethanol is carried out in a composition containing a hydroxide, a catalyst, a solvent, and 2,5-furan diethanol. Including, wherein the dicarboxylate is 2,5-furandicarboxylic acid; and wherein the catalyst is: (a) a support material; and (b) Metal A method comprising:

12. 12. The method of claim 11, wherein the method comprises carrying out the oxidation reaction on a mixture of 5-hydroxymethyl-2-furoic acid and 2,5-furandiethanol in a composition comprising a hydroxide, a catalyst, a solvent, and the mixture of 5-hydroxymethyl-2-furoic acid and 2,5-furandiethanol.

13. 13. The method of claim 12, wherein the mixture comprises 0.35X to 0.65X moles of 5-hydroxymethyl-2-furoic acid and 0.35X to 0.65X moles of 2,5-furandiethanol.

14. 14. The method of any one of claims 10 to 13, wherein the method further comprises polymerizing the dicarboxylate with one or more other monomers to form a polymer.

15. 15. The method of claim 14, wherein the one or more other monomers comprise a diol and the polymer is a polyester.

16. 16. A polymer prepared from the method of claim 14 or 15.

17. 17. An article of manufacture comprising the polymer of claim 16.

18. 2,5-furandicarboxylic acid prepared by the method of any one of claims 1 to 13.

19. 2,5-furandicarboxylic acid according to claim 18, wherein the 2,5-furandicarboxylic acid is crystalline.

20. A polyester comprising a diol and the 2,5-furandicarboxylic acid of claim 18 or 19.

21. 21. An article of manufacture comprising the polyester of claim 20.

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