Synthesis method of 2,5-franzicarboxylic acid by carbonylation of 2-froic acid

Abstract

[Problem] To provide a method for synthesizing 2,5-franjicarboxylic acid by carbonylation of 2-furoic acid. [Solution] This method involves adding 2-froic acid and an organic base to a two-phase solvent system, separating the two phases after the reaction is complete, adding the organic acid to the aqueous phase to form a precipitate, filtering and recovering the precipitate, followed by washing and drying to obtain 2,5-franzicarboxylic acid. Here, the two-phase solvent system is a mixture of an aqueous solution of a basic metal salt and a biomass-derived polar aprotic solvent, and a CO2 donor may be added to the two-phase solvent system. The synthesis process and separation / purification process of the present invention are simple, the product has high purity, the carbonylation reaction rate is fast, and the raw material cost is reduced. Furthermore, the present invention is also in line with the concept of green chemistry (environmentally harmonious chemistry).

Description

Technical Field

[0001] The present invention belongs to the field of furan-based biomass chemicals and materials, and particularly relates to a method for synthesizing 2,5-furandicarboxylic acid by carbonylation of 2-furoic acid.

Background Art

[0002] 2,5-Furandicarboxylic acid (hereinafter referred to as FDCA) is a furan-based compound having an aromatic structure and has high similarity in both structure and function to petroleum-based terephthalic acid.

[0003] [[ID=十六]]Poly(ethylene 2,5-furandicarboxylate) (PEF) obtained from FDCA and ethylene glycol is superior to polyethylene terephthalate (PET) in terms of thermodynamic properties, strength and barrier properties, and is generally recognized as a green dibasic acid monomer that can replace terephthalic acid.

[0004] Therefore, an increase in the demand for FDCA is expected.

[0005] According to a research report published by the New Think Tank Industry Research Center, the global FDCA market is expected to grow at an annual compound growth rate of more than 8.5% from 2022 to 2027 and reach 820 million US dollars in 2027.

[0006] Currently, the synthetic routes of FDCA are mainly classified into three categories. That is, the 5-hydroxymethylfurfural (HMF) oxidation route, the gluconic acid route and the 2-furoic acid route.

[0007] The HMF oxidation route is a route in which HMF is used as a substrate and oxidized by a thermal catalyst or a photocatalyst to produce FDCA, and the catalyst used in this process is usually a noble metal catalyst.

[0008] Although this method has already enabled scale-up production, the high cost of HMF makes the production cost of 2,5-franzicarboxylic acid significantly higher than that of terephthalic acid, limiting the large-scale production and application of FDCA.

[0009] The gluconate pathway is a method for directly synthesizing 2,5-franzicarboxylic acid under appropriate dehydration conditions after selective carboxylation (oxidation) of the C1 and C6 positions of glucose.

[0010] However, the main problem with this pathway lies in the difficulty of selective oxidation in the first step, and the related theories and techniques are still under development.

[0011] The 2-furoic acid pathway mainly involves the direct carbonylation of 2-furoic acid, the bromination of 2-furoic acid, and the disproportionation of 2-furoic acid.

[0012] Banerjee et al. (Nature, 2016, 7593:215-219) reported a method for synthesizing FDCA by direct carbonylation using CO2 as the carbonylation reagent, 2-furoic acid as the substrate, and cesium carbonate as an auxiliary agent.

[0013] Since then, numerous studies have been published on the synthesis of FDCA from 2-flohic acid using carbonates as co-catalysts.

[0014] Chinese patent CN116283849A discloses a method for producing FDCA using cesium salts as raw materials. Chinese patent CN115991686A proposes a method for synthesizing FDCA using an ultrabasic catalyst prepared by supporting a carbonate.

[0015] However, all of these methods involve solid-state heterogeneous reactions, and the reaction conditions are harsh, so no significant progress has been made at present.

[0016] There are two main routes for the production of FDCA by bromination of 2-furoic acid: direct oxidation and a method in which 2-furoic acid is converted to a Grignard reagent and reacted with CO2.

[0017] In all routes, a step of brominating 2-furoic acid is required, and this step is the main factor driving up product costs.

[0018] The production of FDCA by disproportionation of 2-furoic acid was first reported by Ogata et al. (J. Am. Chem. Soc., 1957, 22:6005-6008).

[0019] The report describes a reaction in which benzoic acid and a metal halide salt are mixed to produce benzene and phthalic acid.

[0020] However, this method has the drawbacks of producing franc carboxylic acid with numerous isomers and requiring stringent reaction conditions.

[0021] As described above, conventional FDCA synthesis methods using 2-furoic acid all have problems such as high catalyst costs, harsh reaction conditions, and a large amount of by-products, and there is a strong desire for the development of new, milder, and more economical synthetic routes. [Prior art documents] [Patent Documents]

[0022] [Patent Document 1] China patent CN116283849A [Patent Document 2] China patent CN115991686A [Non-patent literature]

[0023] [Non-Patent Document 1] Banerjee et al. (Nature, 2016, 7593:215-219) [Non-Patent Document 2] Ogata et al. (J. Am. Chem. Soc., 1957, 22:6005-6008) SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0024] In view of the above problems existing in the prior art, the technical problem to be solved by the present invention is to provide a method for synthesizing 2,5-furandicarboxylic acid by carbonylation of 2-furoic acid, aiming to solve the problems that the current production cost of 2,5-furandicarboxylic acid is high and the reaction conditions are severe. MEANS FOR SOLVING THE PROBLEMS

[0025] In order to solve the above problems, the technical means according to the present invention are as follows. A method for synthesizing 2,5-furandicarboxylic acid by carbonylation of 2-furoic acid, wherein 2-furoic acid and an organic base are added to a two-phase solvent system, the two phases are separated after the reaction is completed, an organic acid is added to the aqueous phase to generate a precipitate, which is collected by filtration, and then the precipitate is washed and dried to obtain 2,5-furandicarboxylic acid.

[0026] Here, the two-phase solvent system is a mixed system of an aqueous basic metal salt solution and a polar aprotic solvent derived from biomass, and a CO2 donor may or may not be added to the two-phase solvent system.

[0027] Furthermore, the volume ratio of the aqueous basic metal salt solution to the polar aprotic solvent derived from biomass is 1 to 9:1 to 9.

[0028] Furthermore, the basic metal salt is one or a mixture of two or more of Na2CO3, K2CO3, NaOH and KOH, and the concentration of the aqueous basic metal salt solution is 0.5 to 5 mol / L.

[0029] Preferably, the concentration of the aqueous basic metal salt solution is 0.5 to 1.5 mol / L.

[0030] Furthermore, the biomass-derived polar aprotic solvent is one or more of the following: tetrahydrofuran, acetonitrile, and propylene carbonate.

[0031] Furthermore, the organic base is one or a mixture of two or more of the following: sodium methanol, sodium formate, sodium ethanol, sodium acetate, triphenylacetic acid, and trimethylacetic acid.

[0032] Furthermore, the concentrations of the 2-furoic acid and the organic base in the reaction system are both 0.1 to 1 mol / L.

[0033] Preferably, the concentration of 2-furoic acid is 0.4 to 0.6 mol / L, and the concentration of the organic base is 0.3 to 0.5 mol / L.

[0034] Furthermore, the CO2 donating agent is one or more of the following: triphenylacetic acid, trimethylacetic acid, ethylene carbonate, and propylene carbonate.

[0035] Furthermore, the organic acid is one or more of the following: formic acid, acetic acid, and propionic acid.

[0036] Furthermore, the specific steps are as follows:

[0037] 1) A basic metal salt is dissolved in water to obtain an aqueous solution of the basic metal salt, and this is mixed with a polar aprotic solvent derived from biomass to construct a two-phase solvent system.

[0038] 2) Add the 2-furoic acid and organic base to the two-phase solvent system constructed in step 1) above, and add a CO2 donor reagent if and without, and react at 140-220°C with continuous stirring for 1-12 hours.

[0039] 3) After the reaction is complete, separate the aqueous and organic phases of the reaction system from step 2), recover the organic phase by vacuum distillation at 40-80°C, add the organic acid dropwise to the aqueous phase until no more precipitate is formed, filter and collect the precipitate to obtain crude 2,5-franj carboxylic acid.

[0040] 4) The crude 2,5-franzicarboxylic acid is placed in a washing solution and washed continuously until the electrical conductivity of the washing solution no longer changes significantly, and then dried at room temperature to obtain 2,5-franzicarboxylic acid.

[0041] Furthermore, in step 4), the washing solution is an organic acid alcohol solution, the organic acid being the same as the organic acid used in step 3), and the alcohol being methanol or ethanol.

[0042] The volume ratio of acid to alcohol is 5-9:1-6, preferably 5-8:2-5.

[0043] Preferably, the reaction temperature in step 2) is 160-200°C and the reaction time is 3-6 hours.

[0044] Preferably, the distillation temperature in step 3) is 60-70°C.

[0045] In the present invention, a schematic diagram illustrating the conversion of 2-furoic acid to 2,5-franzicarboxylic acid in a two-phase system is shown below.

[0046] JPEG0007841194000002.jpg98151 Here, base 1 refers to a basic metal salt, and base 2 refers to an organic base. [Effects of the Invention]

[0047] The present invention has the following superior effects compared to the prior art.

[0048] (1) The basic metal salt used in this invention acts as a base and also functions as a phase separation salt, promoting the formation of a two-phase system and assisting in the deprotonation of 2-froic acid. In addition, the biomass-derived polar aprotic solvent acts not only as a solvent but also as a CO2 donor.

[0049] (2) In the present invention, the organic base that promotes the carbonylation reaction decomposes under specific temperatures to produce CO2 and an ultrastrong base, thereby improving the carbonylation reaction rate. After FDCA is produced, the presence of a basic carbonate facilitates the migration of FDCA into the aqueous phase, making it easier to separate the products.

[0050] (3) The solvent used in the present invention functions as a reagent that induces the activation of CO2, significantly lowering the reaction energy barrier of the carbonylation process. As a result, the reaction temperature range (160-200°C) is significantly lower than the conventional direct carbonylation reaction temperature of 2-furoic acid (240-300°C), and the overall pressure of the reaction system (0-0.3 MPa) is also lower than that of conventionally reported 2-furoic acid carbonylation processes (3-10 MPa). Furthermore, the reaction process of the present invention does not use ultrabasic compounds.

[0051] (4) The two-phase solvent system used in the present invention not only functions as a solvent but also possesses catalytic activity, thereby improving the reaction rate. [Brief explanation of the drawing]

[0052] [Figure 1] The 1H-NMR spectrum (a) of FDCA obtained by the present invention is shown. [Figure 2] The 13C-NMR spectrum diagram (b) of FDCA obtained by the present invention is shown. [Modes for carrying out the invention]

[0053] The present invention will be described in more detail below using specific examples. The yield, purity, and conversion rate of FDCA in the following examples are calculated based on the following formula.

[0054] Place 0.1 g of the pre-purification and post-purification products uniformly in petri dishes that have been dried to a constant weight, cover with dust-free paper, and heat in an oven at 105°C for 6 hours until a constant weight is reached to obtain the degree of dryness of the sample.

[0055] The yield Y(FDCA) after FDCA purification is calculated using the following formula.

[0056] JPEG0007841194000003.jpg25166 Here, n(FDCA) is the number of moles of FDCA produced, and n(2-furoic acid 1) is the number of moles of the reaction substrate, 2-furoic acid.

[0057] The purity P(FDCA) of FDCA is calculated using the following formula.

[0058] JPEG0007841194000004.jpg26155 Here, m(FDCA1) is the mass calculated by liquid chromatography, and m(FDCA2) is the measured weighing value.

[0059] The conversion rate C(FDCA) of FDCA is calculated using the following formula.

[0060] JPEG0007841194000005.jpg26157 Here, n(FDCA) is the number of moles of FDCA produced, and n(2-furonic acid 2) is the number of moles of 2-furonic acid consumed in the reaction.

[0061] The purity of the FDCA obtained in the following examples is evaluated by chromatographic purity, and the measurement is performed according to the following procedure.

[0062] Place 0.1 g (dry weight) of the sample in a beaker, add an appropriate amount of warm water to dissolve it, and after cooling to room temperature, bring the total volume to 500 mL.

[0063] Next, the solution filtered through a 0.22 μm organic syringe filter is used as the sample for measuring the FDCA concentration.

[0064] For the analysis, a liquid chromatograph (Waters2695) equipped with a differential refractive detector (2414 RI Detector) and an organic acid analysis column (HPX-87H) is used.

[0065] The analysis conditions are as follows: Flow rate: 0.6 mL / min, column temperature: 55°C, detector temperature: 40°C, mobile phase: 5 mM H2SO4.

[0066] Using the previously created FDCA standard curve, the actual chromatographic concentration of FDCA in the dissolved sample is determined, and the chromatographic purity of the sample is calculated based on that value.

[0067] Example 1 Prepare a 1 mol / L aqueous solution of Na2CO3 and mix it with propylene carbonate in a ratio of 1:9 (v / v) to construct a two-phase solvent system.

[0068] Propylene carbonate also plays a role in supplying CO2.

[0069] Next, 2-furoic acid and triphenylacetic acid are added to the two-phase solvent system to prepare it so that the concentrations of 2-furoic acid and sodium acetate are both 0.4 mol / L in the total solvent (uniformly dissolved in each phase).

[0070] Set the reaction vessel to 160°C and carry out the reaction for 6 hours while continuously stirring.

[0071] After the reaction is complete, the aqueous phase and organic phase are separated using a separatory funnel.

[0072] The organic phase is recovered as a solvent by vacuum distillation using a rotary evaporator set to 60°C.

[0073] Formic acid is added dropwise to the aqueous phase until no more precipitate forms, then filtered and the precipitate is collected to obtain crude FDCA.

[0074] Next, the crude FDCA is repeatedly washed with a formic acid alcohol solution in a methanol-to-formic acid volume ratio of 8:2, and the washing is continued until the electrical conductivity of the washing solution no longer changes.

[0075] Finally, the FDCA is dried at room temperature to obtain high purity.

[0076] Example 2 A 1 mol / L aqueous solution of Na2CO3 was prepared and mixed with acetonitrile in a ratio of 3:7 (v / v) to construct a two-phase solvent system.

[0077] Next, 2-furoic acid and sodium acetate were added to the two-phase solvent system, and the total solvent concentrations of both 2-furoic acid and sodium acetate were set to 0.4 mol / L (the solutes were uniformly dissolved in both phases).

[0078] Subsequently, 10% of the total solvent volume of propylene carbonate was added to the reaction vessel, and the reaction was carried out for 4 hours under continuous stirring at a temperature of 160°C.

[0079] After the reaction was complete, the aqueous and organic phases were separated using a separatory funnel.

[0080] The solvent from the organic phase was recovered by vacuum distillation (using a rotary evaporator) at 60°C.

[0081] Formic acid was added dropwise to the aqueous phase until no more precipitate formed, then filtered and the precipitate was collected to obtain crude FDCA.

[0082] Next, the crude FDCA was washed multiple times with an acetic acid alcohol solution (ethanol to formic acid volume ratio of 7:3) until no change was observed in the electrical conductivity of the washing solution.

[0083] Finally, the FDCA was dried at room temperature to obtain high purity FDCA.

[0084] Example 3 A 1 mol / L aqueous solution of Na2CO3 was prepared and mixed with tetrahydrofuran in a ratio of 3:7 (v / v) to construct a two-phase solvent system.

[0085] Next, 2-furoic acid and triphenylacetic acid were added to the two-phase solvent system, and the total solvent concentrations of both 2-furoic acid and sodium acetate were set to 0.4 mol / L (the solutes were uniformly dissolved in both phases).

[0086] Subsequently, 10% of the total solvent volume of propylene carbonate was added to the reaction vessel, and the reaction was carried out at 160°C with continuous stirring for 6 hours.

[0087] After the reaction was complete, the aqueous and organic phases were separated using a separatory funnel.

[0088] The organic phase was recovered by vacuum distillation at 60°C to recover the solvent.

[0089] Acetic acid was added dropwise to the aqueous phase until no more precipitate formed, and the precipitate was collected by filtration to obtain crude FDCA.

[0090] Next, the crude FDCA was washed multiple times with an acetic acid alcohol solution (methanol to acetic acid volume ratio of 6:4) until the electrical conductivity of the washing solution no longer changed.

[0091] Finally, it was dried at room temperature to obtain FDCA.

[0092] Example 4 A 1 mol / L aqueous solution of Na2CO3 was prepared and mixed with acetonitrile in a ratio of 2:8 (v / v) to construct a two-phase solvent system.

[0093] Next, 2-furoic acid and triphenylacetic acid were added, and the concentrations of 2-furoic acid and triphenylacetic acid in the total solvent were adjusted to 0.4 mol / L and 0.6 mol / L, respectively (the solutes dissolved uniformly in both phases).

[0094] Subsequently, propylene carbonate equivalent to 10% of the total solvent volume was added to the reaction vessel, and the reaction was carried out with continuous stirring at 180°C for 4 hours.

[0095] After the reaction, the aqueous and organic phases were separated using a separatory funnel.

[0096] The solvent was recovered from the organic phase by vacuum distillation at 60°C. Formic acid was added dropwise to the aqueous phase until no more precipitate formed, and the precipitate was collected by filtration to obtain crude FDCA.

[0097] Next, the crude FDCA was washed multiple times with a formic acid alcohol solution (methanol to formic acid volume ratio 6:4) until there was no change in the electrical conductivity of the washing solution.

[0098] Finally, it was dried at room temperature to obtain FDCA.

[0099] Example 5 A 1 mol / L aqueous solution of K2CO3 was prepared and mixed with tetrahydrofuran in a ratio of 3:7 (v / v) to construct a two-phase solvent system.

[0100] Next, 2-furoic acid and trimethylacetic acid were added to the two-phase solvent system, and the concentrations of 2-furoic acid and trimethylacetic acid in the total solvent were adjusted to 0.4 mol / L and 0.8 mol / L, respectively (the solutes were uniformly dissolved in both phases).

[0101] 10% of the total solvent volume of propylene carbonate was added to the reaction vessel, and the reaction was carried out with continuous stirring at 180°C for 6 hours.

[0102] After the reaction, the aqueous and organic phases were separated using a separatory funnel.

[0103] The organic phase was distilled under reduced pressure at 60°C to recover the solvent. Formic acid was added dropwise to the aqueous phase until no more precipitate formed, and the precipitate was collected by filtration to obtain crude FDCA.

[0104] Next, the crude FDCA was washed multiple times with an acetic acid alcohol solution (ethanol to formic acid in a volume ratio of 7:3) until the electrical conductivity of the washing solution no longer changed.

[0105] Finally, the FDCA was obtained by drying at room temperature.

[0106] Example 6 A 1 mol / L aqueous solution of K2CO3 was prepared and mixed with tetrahydrofuran in a ratio of 2:8 (v / v) to construct a two-phase solvent system.

[0107] Next, 2-furoic acid and sodium acetate were added, and the total concentration of both in the solvent was adjusted to 0.8 mol / L (the solute was uniformly dissolved in both phases).

[0108] Subsequently, propylene carbonate at 10% of the total solvent volume was added, and the reaction was carried out with continuous stirring at 200°C for 6 hours.

[0109] After the reaction, the aqueous and organic phases were separated using a separatory funnel.

[0110] The solvent was recovered from the organic phase by vacuum distillation at 60°C. Formic acid was added dropwise to the aqueous phase until no more precipitate formed, and the precipitate was collected by filtration to obtain crude FDCA.

[0111] Next, the crude FDCA was washed multiple times with a formic alcohol solution (methanol to formic acid volume ratio of 8:2) until the electrical conductivity of the washing solution no longer changed.

[0112] Finally, the FDCA was obtained by drying at room temperature.

[0113] Example 7 A 1 mol / L aqueous solution of NaOH was prepared and mixed with propylene carbonate in a ratio of 3:7 (v / v) to construct a two-phase solvent system.

[0114] Propylene carbonate also acts as a CO2 donor.

[0115] Next, 2-furoic acid and sodium acetate were added to the two-phase solvent system, and the total solvent concentrations of both 2-furoic acid and sodium acetate were set to 0.6 mol / L (the solutes were uniformly dissolved in both phases).

[0116] Subsequently, the reaction vessel was set to 200°C and the reaction was carried out for 6 hours under continuous stirring.

[0117] After the reaction was complete, the aqueous and organic phases were separated using a separatory funnel.

[0118] The organic phase was recovered by vacuum distillation at 60°C, and acetic acid was added dropwise to the aqueous phase until no more precipitate formed.

[0119] The precipitate was collected by filtration to obtain crude FDCA.

[0120] Next, the crude FDCA was washed multiple times with an acetic acid alcohol solution (ethanol to acetic acid volume ratio of 8:2) until no change was observed in the electrical conductivity of the washing solution.

[0121] Finally, the FDCA was dried at room temperature to obtain it.

[0122] Example 8 A 1 mol / L aqueous solution of NaOH was prepared and mixed with acetonitrile in a ratio of 3:7 (v / v) to construct a two-phase solvent system.

[0123] Next, 2-furoic acid and triphenylacetic acid were added to the two-phase solvent system, and the total concentration of both in the solvent was set to 0.4 mol / L (the solute was uniformly dissolved in both phases).

[0124] Furthermore, 10% of the total solvent volume of propylene carbonate was added, the reaction vessel was set to 200°C, and the reaction was carried out for 4 hours under continuous stirring.

[0125] After the reaction was complete, the aqueous and organic phases were separated using a separatory funnel.

[0126] The organic phase was recovered by vacuum distillation at 60°C, and formic acid was added dropwise to the aqueous phase until no more precipitate formed.

[0127] The precipitate was collected by filtration to obtain crude FDCA.

[0128] Next, the crude FDCA was washed multiple times with a formic acid alcohol solution (ethanol to formic acid volume ratio of 8:2) until the electrical conductivity of the washing solution no longer changed.

[0129] Finally, it was dried at room temperature to obtain FDCA.

[0130] Example 9 A 1 mol / L aqueous solution of KOH was prepared and mixed with acetonitrile in a ratio of 2:8 (v / v) to construct a two-phase solvent system.

[0131] Next, 2-furoic acid and trimethylacetic acid were added to the two-phase solvent system, and their concentrations in the total solvent were adjusted to 0.4 mol / L and 0.6 mol / L, respectively (the solutes were uniformly dissolved in both phases).

[0132] Trimethylacetic acid also acts as a CO2 donor.

[0133] The reaction vessel was set to 180°C, and the reaction was carried out for 6 hours under continuous stirring.

[0134] After the reaction was complete, the aqueous and organic phases were separated using a separatory funnel.

[0135] The organic phase was recovered by vacuum distillation at 60°C to recover the solvent.

[0136] Acetic acid was added dropwise to the aqueous phase until no more precipitate formed, and the precipitate was collected by filtration to obtain crude FDCA.

[0137] Next, the crude FDCA was washed multiple times with an acetic acid alcohol solution (methanol to acetic acid volume ratio of 7:3) until the electrical conductivity of the washing solution no longer changed.

[0138] Finally, it was dried at room temperature to obtain FDCA.

[0139] Example 10 A 1 mol / L aqueous solution of KOH was prepared and mixed with acetonitrile in a ratio of 4:6 (v / v) to construct a two-phase solvent system.

[0140] Next, 2-furoic acid and sodium ethanol were added to the two-phase solvent system, and their concentrations in the total solvent were adjusted to 0.4 mol / L and 0.8 mol / L, respectively (the solutes were uniformly dissolved in both phases).

[0141] Subsequently, 10% of the total solvent volume of propylene carbonate was added, the reaction vessel was set to 160°C, and the reaction was carried out for 4 hours under continuous stirring.

[0142] After the reaction was complete, the aqueous and organic phases were separated using a separatory funnel.

[0143] The organic phase was recovered by vacuum distillation at 60°C, and acetic acid was added dropwise to the aqueous phase until no more precipitate formed.

[0144] The precipitate was collected by filtration to obtain crude FDCA.

[0145] Next, the crude FDCA was washed multiple times with an acetic acid alcohol solution (methanol to acetic acid volume ratio of 7:3) until no change was observed in the electrical conductivity of the washing solution.

[0146] Finally, the FDCA was obtained by drying at room temperature.

[0147] Example 11 A 0.5 mol / L aqueous solution of K2CO3 was prepared and mixed with acetonitrile in a ratio of 3:7 (v / v) to construct a two-phase solvent system.

[0148] Next, 2-furoic acid and trimethylacetic acid were added to the two-phase solvent system, and their concentrations in the total solvent were adjusted to 0.4 mol / L and 0.8 mol / L, respectively (the solutes were uniformly dissolved in both phases).

[0149] Next, propylene carbonate at 10% of the total solvent volume was added, the reaction vessel was set to 180°C, and the reaction was carried out for 6 hours under continuous stirring.

[0150] After the reaction was complete, the aqueous and organic phases were separated using a separatory funnel.

[0151] The organic phase was recovered by vacuum distillation at 60°C, and formic acid was added dropwise to the aqueous phase until no more precipitate formed.

[0152] The precipitate was collected by filtration to obtain crude FDCA.

[0153] Next, the crude FDCA was washed multiple times with a formic acid alcohol solution (ethanol to formic acid volume ratio of 8:2) until there was no change in the electrical conductivity of the washing solution.

[0154] Finally, the FDCA was dried at room temperature to obtain it.

[0155] Example 12 A 0.5 mol / L aqueous solution of NaOH was prepared and mixed with acetonitrile in a ratio of 2:8 (v / v) to construct a two-phase solvent system.

[0156] Next, 2-furoic acid and triphenylacetic acid were added to the two-phase solvent system, and the total concentration of both in the solvent was adjusted to 0.8 mol / L (the solute was uniformly dissolved in both phases).

[0157] Furthermore, 10% of the total solvent volume of propylene carbonate was added, the reaction vessel was set to 160°C, and the reaction was carried out for 4 hours under continuous stirring.

[0158] After the reaction was complete, the aqueous and organic phases were separated using a separatory funnel.

[0159] The organic phase was recovered by vacuum distillation at 60°C, and formic acid was added dropwise to the aqueous phase until no more precipitate formed.

[0160] The precipitate was collected by filtration to obtain crude FDCA.

[0161] Next, the crude FDCA was washed multiple times with a formic acid alcohol solution (ethanol to formic acid volume ratio of 8:2) until no change was observed in the electrical conductivity of the washing solution.

[0162] Finally, it was dried at room temperature to obtain FDCA.

[0163] Example 13 A 1 mol / L aqueous solution of NaCl was prepared and mixed with N,N-dimethylformamide (DMF) in a ratio of 2:8 (v / v) to construct a two-phase solvent system.

[0164] Next, 2-furoic acid and sodium acetate were added to the two-phase solvent system, and the total solvent concentrations of both 2-furoic acid and sodium acetate were set to 0.8 mol / L (the solutes were uniformly dissolved in both phases).

[0165] Subsequently, propylene carbonate equivalent to 10% of the total solvent volume was added to the reaction vessel, and the reaction was carried out for 4 hours under continuous stirring at a temperature of 180°C.

[0166] After the reaction was complete, the aqueous and organic phases were separated using a separatory funnel.

[0167] The organic phase was subjected to vacuum distillation at 60°C to recover the solvent, and formic acid was added dropwise to the aqueous phase until no more precipitate formed.

[0168] The precipitate was recovered by filtration to obtain crude FDCA.

[0169] Next, the crude FDCA was washed multiple times with a formic acid alcohol solution (ethanol to formic acid volume ratio of 8:2) until no significant change was observed in the electrical conductivity of the washing solution.

[0170] Finally, the FDCA was dried at room temperature to obtain it.

[0171] Table 1. Yield and conversion rate of FDCA products obtained in Examples 1-13. JPEG0007841194000006.jpg197164

[0172] The purity of the FDCA obtained in Examples 1 to 12 of the present invention was 99% or higher. In Example 13, the yield of FDCA could not be measured due to the characteristics of the solvent used.

[0173] Table 1 shows the yield and conversion rate of the FDCA products obtained in Examples 1-13. As is clear from the table, the type of solvent is extremely important in the catalytic synthesis of FDCA. Furthermore, it can be seen that the ratio of the mixed solvent, reaction temperature, reaction time, and the type and concentration of the alkali and basic salts are closely correlated with the purity of the FDCA.

[0174] Furthermore, using a mixed acid alcohol washing solution effectively removes salts and other contaminants from the product while simultaneously minimizing FDCA elution. As a result, it becomes possible to achieve a relatively high yield while maintaining high purity.

[0175] Figure 1 shows the FDCA obtained by the present invention. 1 The 1H-NMR spectrum (a) is shown. The peaks at 7.29 ppm and 13.62 ppm represent characteristic chemical shifts corresponding to hydrogen atoms in the FDCA molecule, respectively. The absence of any other significant chemical shift peaks confirms that the purified product is of extremely high purity.

[0176] Figure 2 shows the FDCA obtained by the present invention. 13 The 1C-NMR spectrum (b) is shown. The peaks at 118.2 ppm, 146.8 ppm, and 158.6 ppm represent characteristic chemical shifts corresponding to carbon atoms in the FDCA molecule, respectively. No other significant chemical shift peaks were observed, indicating that the purified product is extremely pure.

Claims

1. A method for synthesizing 2,5-franjicarboxylic acid by carbonylation of 2-furoic acid, The process involves adding 2-furoic acid and a mixture of one or more of triphenylacetic acid, sodium acetate, trimethylacetic acid, and sodium ethoxide to a two-phase solvent system, and separating the two phases after the reaction is complete. A step of adding an organic acid to the aqueous phase to generate a precipitate, and then filtering and recovering the precipitate, The process includes a step of washing and drying the precipitate to obtain 2,5-franzicarboxylic acid. The aforementioned two-phase solvent system is a mixture of an aqueous solution of a basic metal salt and a biomass-derived polar aprotic solvent. The basic metal salt is one or a mixture of two or more of Na₂CO₃, K₂CO₃, NaOH, and KOH. The biomass-derived polar aprotic solvent is one or more of tetrahydrofuran, acetonitrile, and propylene carbonate, If the biomass-derived polar aprotic solvent does not contain a CO2 donor, then CO2 is added to the two-phase solvent system. ２ A CO2 donor is added, and the CO2 donor is characterized by being one or more of the following: triphenylacetic acid, trimethylacetic acid, ethylene carbonate, and propylene carbonate. A method for synthesizing 2,5-franjilic acid by carbonylation of 2-furoic acid.

2. The method according to claim 1, characterized in that the volume ratio of the aqueous solution of the basic metal salt to the biomass-derived polar aprotic solvent is 1 to 9:1 to 9.

3. The method according to claim 1 or 2, characterized in that the concentration of the aqueous solution of the basic metal salt is 0.5 to 5 mol / L.

4. The method according to claim 1, characterized in that the concentrations of the 2-furoic acid and a mixture of one or more of triphenylacetic acid, sodium acetate, trimethylacetic acid, and sodium ethoxide in the reaction system are all 0.1 to 1 mol / L.

5. The method according to claim 1, characterized in that the organic acid is one or a mixture of two or more of formic acid, acetic acid, and propionic acid.

6. 1) Dissolving the basic metal salt in water to obtain an aqueous solution of the basic metal salt, and then mixing the aqueous solution of the basic metal salt with a biomass-derived polar aprotic solvent to prepare a two-phase solvent system, 2) Add 2-furoic acid and a mixture of one or more of the triphenylacetic acid, sodium acetate, trimethylacetic acid, and sodium ethoxide to the two-phase solvent system prepared in step 1), and the biomass-derived polar aprotic solvent is the CO ２ If the donor is not present, the CO2 donor is added, and a continuous stirring reaction is carried out at 140 to 220°C for 1 to 12 hours. 3) After the reaction is complete, the aqueous and organic phases of the reaction system are separated, the organic phase is recovered by vacuum distillation at 40-80°C, and then an organic acid is added dropwise to the aqueous phase until no more precipitate forms. The precipitate is then filtered and recovered to obtain crude 2,5-franzicarboxylic acid. 4) The crude 2,5-franján carboxylic acid is continuously washed in a washing solution until there is no significant change in the electrical conductivity of the washing solution, and then dried at room temperature to obtain 2,5-franján carboxylic acid. The method according to claim 1, characterized by including

7. The method according to claim 6, characterized in that, in step 4), the cleaning solution is an organic acid alcohol solution, the organic acid is the same as the organic acid used in step 3), the alcohol is methanol or ethanol, and the volume ratio of acid to alcohol is 5 to 9:1 to 6.

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