Mechanistic investigation of cellulose formate to 5-hydroxymethylfurfural conversion in DMSO-H2O

Abstract

5-hydroxymethylfurfural (HMF) primary can be synthesized from monosaccharides including glucose and fructose, cost is one of barriers to realize HMF large-scale production. In this study, a high HMF yield of 69.6 mol% was obtained at 180℃ for 5 min using biomass derived cellulose formate as reactant, which was prepared by formylation of cellulose using recyclable formic acid, and sequentially catalyzed by hydrochloric acid (HCl) and aluminum chloride (AlCl3) in dimethyl sulfoxide (DMSO) and H2O system. To investigate the effect of cosolvents and formyl groups on the cellulose formate conversion, kinetics analysis and molecular dynamics simulations were conducted. Reaction kinetics study shows that the rate constant of hydrolysis of cellulose formate to glucose increased by almost three times in DMSO-H2O and the reaction rates’ constants of glucose, fructose and HMF to humins decreased with the presence of DMSO. Molecular dynamics simulations show that formyl group and DMSO increased its hydrophilicity around the reactive hydroxyl group on the carbon ring and steric hindrance of formyl group affect the distribution of water molecular and DMSO molecular around formylated glucose, resulting in facilitating the formation of a precursor to fructose and inhibiting the formation of humins during formylated glucose conversion.