Method for synthesizing 2,5-furandicarboxylic acid by catalyzing carbon dioxide with n-heterocyclic carbene

[0030] Step 1: Add 1.26g of methyl furoate, 0.118g of azacyclic carbene and 44.2mg of rhodium acetate dimer into a dry flask, add 30mL of DMF, and vacuum into CO 2 , and reacted at 150° C. for 48 hours to obtain the crude product of methyl 2,5-furandicarboxylate 2-carboxylate. After column chromatography, 1.47 g of methyl 2,5-furandicarboxylate was obtained with a yield of 86.41%.

[0031] Step 2: 1.47g of 2,5-furandicarboxylic acid methyl 2-carboxylate and sodium hydroxide were dissolved in methanol, and reacted at 60°C for 14 hours to obtain 1.45g of 2,5-furandicarboxylic acid salt crude product with a yield of 100% .

[0032] Step 3: Remove the solvent from 1.45 g of crude 2,5-furandicarboxylate in vacuo, add an appropriate amount of deionized water, and extract three times with an appropriate amount of dichloromethane; acidify the organic layer with concentrated hydrochloric acid until PH = 2; use a heterogeneous solution 250 mL of ethyl acetate for extraction. The organic

[0034] Step 1: Add 1.40g of ethyl furoate, 0.118g of azacyclic carbene and 44.2mg of rhodium acetate dimer into a dry flask, add 30mL of DMF, and vacuum into CO 2 , reacted at 150°C for 48h to obtain a crude product of ethyl 2,5-furandicarboxylate 2-carboxylate, and obtained 1.53g ethyl 2,5-furandicarboxylate through column chromatography, with a yield of 83.08%.

[0035] Step 2: Dissolve 1.53g of ethyl 2,5-furandicarboxylate and sodium hydroxide in methanol and react at 60°C for 14 hours to obtain 1.396g of crude 2,5-furandicarboxylate, with a yield of 100% .

[0036] Step 3: 1.396g of crude 2,5-furandicarboxylate was removed from the solvent in vacuo, added an appropriate amount of deionized water, and extracted three times with an appropriate amount of dichloromethane; the organic layer was acidified with concentrated hydrochloric acid until PH = 2; the heterogeneous solution was used 250 mL of ethyl acetate for extraction. The organic layer was dried over anhydrous sodium s

[0038] Step 1: Add 1.54g propyl furoate, 0.118g azacyclic carbene and 44.2mg rhodium acetate dimer to a dry flask, add 30mL DMF, and vacuum into CO 2 , and reacted at 150°C for 48 hours to obtain a crude product of 2,5-furandicarboxylic acid 2-propyl carboxylate. After column chromatography, 1.47g of 2,5-furandicarboxylic acid 2-propyl carboxylate was obtained, and the yield was 74.18%.

[0039] Step 2: Dissolve 1.47g of 2,5-furandicarboxylic acid propyl 2-carboxylate and sodium hydroxide in methanol and react at 60°C for 14 hours to obtain 1.247g of 2,5-furandicarboxylate crude product with a yield of 100% .

[0040] Step 3: 1.247g of crude 2,5-furandicarboxylate was vacuum removed from the solvent, added an appropriate amount of deionized water, and extracted three times with an appropriate amount of dichloromethane; the organic layer was acidified with concentrated hydrochloric acid until PH = 2; the heterogeneous solution was used 250 mL of ethyl acetate for extraction. The