Dimethylsulfoxide/Water Mixed Solvent Mediated Synthesis of 5-Hydroxymethylfurfural from Galactose with Aluminum Salt Catalyst

As a biomass-derived platform compound, 5-hydroxymethylfurfural (5-HMF) has attracted many researchers' interest. Effective conversion of fructose, glucose and their polymers into 5-HMF provides new perspectives for biomass utilization. However, other underused hexoses have received much less attention in the field of 5-HMF production. In this work, galactose was effectively converted into 5-HMF under mild conditions. AlCl3 center dot 6H(2)O showed superior catalytic activity for the production of 5-HMF in a DMSO/H2O mixed solvent system. Adding an appropriate amount of water in DMSO may have improved the solubility of AlCl3 center dot 6H(2)O and suppressed side reactions, significantly increasing 5-HMF yield and selectivity. The system was also efficient for the conversion of lactose into 5-HMF. Control experiments with different catalysts and simple model compounds provided mechanistic insights.