Practical DMSO-promoted selective hydrolysis–oxidation of lignocellulosic biomass to formic acid attributed to hydrogen bonds

Abstract

Formic acid (HCO₂H) is widely used in various chemical processes, applied in fuel cells, and considered as a promising candidate for hydrogen storage. Currently, industrial production of HCO₂H mainly depends on fossil resources using multiple processes. Practical HCO₂H production from renewable resources for the potential industrial application is rare. Herein, we demonstrate practical dimethyl sulfoxide (DMSO) (1 v%)-promoted selective hydrolysis–oxidation of lignocellulosic biomass to HCO₂H, which is demonstrated by recycling experiments of near 10 gram-scale wheat straw with constantly high efficiencies. Mechanism studies on the major unit of lignocellulosic biomass, glucose, disclose that the high selectivity and yield of HCO₂H are attributed to the hydrogen bonds of DMSO with generated gem-diol groups from the reaction of glucose, or the intermediates of glycolaldehyde and glyoxal with water (H₂O). The formation of hydrogen bonds is indicated both by DFT calculations and IR experiments.