Preparation of 2,5-furandicarboxylic acid from carbohydrates via 5-acetoxymethylfurfural as intermediate in a single acetic acid system

FDCA (2,5-furandicarboxylic acid), produced by oxidizing carbohydrate-derived HMF (5-hydroxymethylfurfural), is a valuable monomer for biopolymers. The difference in the solvent system between the dehydration reaction and oxidation reactions seriously affects the process continuity and production efficiency. Herein, we reported a cascade process for FDCA production from carbohydrates in a single acetic acid system. The fructose conversion was complete and total furan compounds yield reached nearly 90%, which contained 42.8% HMF and 47.1% 5-acetoxymethylfurfural (AMF) in the acetic acid system with NaBr addition. After the azeotropic distillation and vacuum distillation in situ, AMF, a more stable intermediate than HMF, could be easily collected with 90.5% recovery and 99.9% purity. AMF was also oxidized into FDCA with 91.1% yield by Co/Mn/Br catalysts in the acetic acid system. Finally, the cascade process, including fructose dehydration–esterification and HMF/AMF mixture oxidation, was successfully realized in a single acetic acid system. This process is simple to operate, easy to implement, eliminates the use of extra acid or self-made catalysts and expensive solvents, and has the potential for continuous preparation from carbohydrates to FDCA. Graphical Abstract