Conversion of biomass-derived monosaccharides to 2-methylfuran in supercritical acetone

Abstract

2-Methylfuran (2-MF) is an important organic intermediate with a wide range of applications in the pharmaceutical, pesticide and fine chemical industries. The existing industrial route to 2-MF relies on furfural derived from energy-intensive, multi-step conversion of xylose via catalytic hydrodeoxygenation, which requires potentially hazardous hydrogen handling. In this study, we present a novel one-pot pathway to directly convert monosaccharides and acetone to 2-MF in supercritical acetone. The reaction conditions, including the dosage of water, reaction temperature, reaction time, and the dosage of xylose, were optimized (11 mL water, 260 °C, 2 h, 200 mg xylose), where a maximum yield of 31.6 C mol% of 2-MF was obtained. Substantial yields for 2,5-dimethyl-3(2H)-furanone (DFR) and 3-hexene-2,5-diketone (HDK) were obtained, reaching 5.2 C mol% and 13.9 C mol%, respectively, which indicates possible near-complete valorization of the C5 feedstock. A combination of DFT calculations and ¹³C experiments revealed that the reaction initially proceeded via C–C bond cleavage of xylose by OH⁻ from water or acetone to form the C2 fragment, glycolaldehyde (GA), and the C3 fragments, glyceraldehyde (GLA) or dihydroxyacetone (DHA). Then GA reacted with acetone to form 2-MF, and the C3 fragments were converted to DFR and HDK by acetone itself. This work not only elucidates a new effective way to produce 2-MF directly but also highlights the potential of supercritical acetone as a versatile solvent system for biomass valorization.