LAUSR

Imidazole (Im) and benzenesulfonic acid (BSA) formed deep eutectic solvents (DESs) were used as acidic catalyst and solvent for the dehydration of fructose to 5-hydroxymethylfurfural (5-HMF). The DES formation involved an acid–base neutralization to produce equimolar salt from BSA and Im, and subsequent interaction between equimolar salt as hydrogen bond acceptor and excessive BSA as hydrogen bond donor. The BSA-rich DES [Im:1.5BSA] with a 1:1.5 molar ratio of Im:BSA and 10% dosage exhibited high catalytic activity for fructose dehydration with a 5-HMF yield of 90.1% at 100 °C after a very short reaction time (3 min). The bifunctionality of [Im:1.5BSA] for promoting reaction rates and catalytic activity of fructose dehydration has been identified by tuned acidity of DESs and hydrogen bond interaction among fructose, 5-HMF, and DESs demonstrated by conductor-like screening model for real solvents (COSMO-RS) theory.