Conversion of fructose to 5-hydroxymethylfurfural in ternary deep eutectic solvents based biphasic system at mild temperature

The catalytic conversion of fructose to 5-hydroxymethylfurfural (5-HMF) in ternary deep eutectic solvent (DES)/methyl isobutyl ketone (MIBK) biphasic system at mild temperatures (50~70 ℃) was investigated in this work. The ternary DES consists of choline chloride (ChCl), benzene sulfonic acid (BSA) and ethylene glycol (EG) were physiochemical characterized by FT-IR and 1H NMR. The ternary DES(ChCl-BSA-EG)/MIBK biphasic system (ChCl/BSA/EG=2:1:1) resulted in 82.0% 5-HMF yield and 96.2% corresponding selectivity at 60 °C for 2 h. The kinetic analysis further revealed that the rate constant of fructose dehydration (k1) was much higher than the rate constant of 5-HMF conversion (k2). The calculated ratio of k1/k2 was 16.1. The proposed reaction mechanism suggested that the synergetic effect of the three components of ternary DES facilitates the elimination of water molecules from fructose and the formation of 5-HMF, while the MIBK extraction phase suppress the byproducts of 5-HMF as well. The present work provides a green and sustainable pathway for 5-HMF production with high yield and high selectivity at mild temperatures.