Effective Strategy for High-Yield Furan Dicarboxylate Production for Biobased Polyester Applications

A unique strategy for the formation of furan-2,5-dicarboxylic acid (FDCA)-derived esters with methanol and ethylene glycol in concentrated solutions was reported using a six-membered ring acetal of (5-hydroxymethyl)furfural (HMF) with 1,3-propanediol in order to improve the economics for the production of polyethylene 2,5-furandicarboxylate (PEF), a biobased polyester. Aerobic oxidative esterification with methanol and ethylene glycol in the presence of a CeO ₂ -supported Au catalyst gave 80-95% yields of methyl furan-2,5-dicarboxylate and bis(2-hydroxyethyl)furan-2,5-dicarboxylate from concentrated HMF-acetal solutions (10-20 wt %). Kinetic studies combined with density functional theory (DFT) calculations were used to identify two key steps for the conversion of the cyclic acetal ring to the corresponding methyl ester: (i) partial hydrolysis of the acetal ring by OH ⁻ ions and (ii) subsequent oxidation of the hemiacetal in solution by molecular O ₂ on Au nanoparticles. These results represent a significant contribution not only to cutting-edge conversion technology for renewable biomass feedstocks to PEF-based applications but also to opportunities for the efficient conversion of substrates with a reactive formyl group in high yield.