Catalytic Synthesis of 2,5-Furandicarboxylic Acid from Furoic Acid: Transformation from C5 Platform to C6 Derivatives in Biomass Utilizations

2,5-Furandicarboxylic acid (2,5-FDCA), a renewable alternative to p-phthalic acid, is the most promising subproduct from 5-hydroxymethylfurfural (HMF). However, HMF is currently synthesized from mono- and polysaccharides like glucose and fructose with limited volume, which apparently blocks the utilization of 2,5-FDCA to replace p-phthalic acid in the polymer industry. Here, we presented a novel route to 2,5-FDCA originating from C5-based furfural which is industrially produced from bulky raw biomaterials, and is not competitive with food for humans. The starting chemical of this synthesis is furoic acid which is currently produced from furfural. Furoic acid can be feasibly transformed to 2,5-FDCA through consecutive bromination, esterification, carbonylation, and hydrolysis with 65% total yield in four steps and above 80% isolated yield in each step. In particular, the key step, palladium-catalyzed carbonylation of ethyl 5-bromo-furan-2-carboxylate, retains 90% isolated yield in the scale-up synthesis. The route introduced here has offered a promising opportunity to access HMF products from furfural derivatives with a large market; meanwhile it offers one of the key C1 resources, that is, CO, a promising utilization in industry.