Production of 5-hydroxymethylfurfural and furfural from a mixed saccharide feedstock in biphasic solvent systems

The industrial platform chemicals 5-hydroxymethylfurfural (HMF) and furfural (FF) were produced from mixed mono- and oligosaccharides in a hydrolysate obtained from the prehydrolysis of radiata pine wood chips. The conversions were performed at high temperatures in an autoclave using either a THF/water biphasic system under both Brønsted and Lewis acid catalysis provided by NaHSO4/ZnSO4, or an acetone/water biphasic system under Brønsted acid catalysis afforded by H3PO4. Treatment in a THF/water system at 160 °C for 90 min gave the highest yields of HMF (40 molar%) and FF (58 molar%), while the best conditions for the acetone-water system were 180 °C/80 min for HMF (36 molar%) and 170 °C/30 min for FF (62% molar%). Yields for HMF and FF were based on respective hexose and pentose saccharide contents of the solids. The results show that mixed saccharide by-products of thermo-mechanical pulping can be converted into furans at moderately high yields by both catalytic systems.