Production method | 1. It is obtained by the reaction of furfural and malonic acid. Add furfural and malonic acid to pyridine, heat and reflux for 2 hours, cool, add water, and add concentrated ammonia water under stirring until the acid is almost completely dissolved. Filter the solution, wash the filter cake with a small amount of water, combine the filtrate with the washing solution, acidify with hydrochloric acid, and then heat it on a boiling water bath for 1.5-2h. The precipitated precipitate is filtered out, washed with water, and dried to obtain a finished product with a yield of 90-92%. 2. It is obtained by oxidation of furan acrolein [623-30-3] and acid analysis. The mixture of water, furan acrolein, silver oxide and water is added to the reaction pot, and oxygen is introduced at about 25 ℃ under stirring. After 10min, 35-50% sodium hydroxide solution is added dropwise, and 1/2 amount is added within 1h at a temperature lower than 40 ℃. After the other half of sodium hydroxide solution is added within 10min, oxygen is introduced for 10min, pH is controlled to be 11-12, and cooled to below 40 ℃ for discharge and filtration. The filter cake is silver oxide and is applied after washing. The washing and filtrate is adjusted to pH 3 with hydrochloric acid, heated to 90 ℃, all the precipitated furan acrylic acid crystals are dissolved, then cooled to 30 ℃, precipitated crystals, filtered, washed with ice water, and dried to obtain furan acrylic acid. 3. It is obtained by condensation of furfural and acetic anhydride. In a dry reaction pot, acetic anhydride, furfural and anhydrous sodium acetate are added, stirred and refluxed at 150 ℃ for 7 hours, crushed ice is added, and crude products are filtered out. The crude product is mixed and suspended in hot water for heating, and alkali is added to adjust the pH to 5.9-6. After the crude product is completely dissolved, activated carbon is added to decolorise at 90 ℃, filtered, the filtrate is adjusted to pH 3 with hydrochloric acid at 50-60 ℃, crystallization is precipitated, filtered, washed with water, and dried to obtain furan acrylic acid. In addition, furfural and acetone are condensed in sodium hydroxide solution to obtain furfuryl acetone first, and then oxidized with bleaching powder to obtain the product with a yield of more than 65%. |