Efficient selective dehydration of fructose and sucrose into 5-hydroxymethylfurfural (HMF) using dicationic room temperature ionic liquids as a catalyst

Dicationic room temperature ionic liquids (RTILs), with short oligo ethylene glycol linkers have been found to be highly active catalyst for the selective dehydration of fructose and sucrose into 5-hydroxymethylfurfural (HMF). The bis (N-methylimidazolium) cations containing short oligo ethylene glycol linkers and mesylate (CH3SO3-) anions based ILs were employed in catalytic amount for sugar dehydration reactions. As a result, 92.3% of HMF yield was obtained from fructose in 40 min with one equivalent of ITetraEG(mim)(2)][OMs](2) at 120 degrees C. While, 67.2% of HMF was achieved from dehydration of sucrose at 120 degrees C in 150 min using two equivalents of [TetraEG(mim)(2)][OMs](2). Among those dicationic RTILs, [TetraEG(mim)(2)[OMs](2) RTIL was observed to be the most efficient catalyst, demonstrated by its ability to achieve 100% conversion and highest yield of HMF. In addition, effect of reaction time, molar ratio, temperature, and co-catalyst effect were discussed. The use of dicationic RTILs as a catalyst in sugar dehydration greatly reduces the equimolar ratio of catalyst and reaction time required for conversion of sugar into HMF. (C) 2012 Elsevier B.V. All rights reserved.