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 A degrees 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 A degrees 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).
- Metal salts