The Catalytic Conversion of d-Glucose to 5-Hydroxymethylfurfural in DMSO Using Metal Salts

A wide range of metal halides and triflates were examined for the conversion of d -glucose to HMF in DMSO. Chromium and aluminium salts were identified as the most promising catalysts. The effect of process variables like initial d -glucose concentration (0.1–1.5 M), reaction time (5–360 min) and reaction temperature (100–140 °C) on the yield of HMF were examined at a fixed Al(OTf) 3 concentration (50 mM). Highest yields of HMF (60 mol%) were obtained using 1 M d -glucose (16 wt%), Al(OTf) 3 (5 mol%) at a temperature of 140 °C. A reaction pathway involving initial isomerisation of d -glucose to d -fructose followed by a number of dehydration steps is proposed. Kinetic analysis reveals that the reaction is second order in d -glucose with an activation energy of 138 kJ mol −1 .