Abstract:[Objective] This study aims to develop a lipase-mediated furfural oxidation system in ionic liquid for the green synthesis of furoic acid, 5-hydroxymethyl-2-furancarboxylic acid, and 2,5-furandicarboxylic acid under mild reaction conditions. [Method] Using furfural as the substrate, Novozym 435 lipase as the catalyst, hydrogen peroxide as the oxidant, and 1-butyl-3-methylimidazolium acetate ionic liquid as the solvent, the conditions including reaction temperature, reaction time, initial furfural concentration, and initial hydrogen peroxide concentration were optimized. The system was further extended to the oxidation of 5-hydroxymethylfurfural, and coupled with a chemical oxidation process using an imidazolium-based ionic liquid and tert-butyl hydroperoxide to achieve one-pot synthesis of 2,5-furandicarboxylic acid. [Result] Under the optimized conditions, the yield of furoic acid exceeded 99%. The oxidation of 5-hydroxymethylfurfural to 5-hydroxymethyl-2-furancarboxylic acid achieved yield of 94%. 2,5-furandicarboxylic acid was synthesized via the one-pot coupled reaction with a yield of 90%. [Conclusion] This study provides a novel strategy and methodology for the green synthesis of bio-based chemicals such as furoic acid and 2,5-furandicarboxylic acid.
