Efficient catalytic conversion of the fructose into 5-hydroxymethylfurfural by heteropolyacids in the ionic liquid of 1-butyl-3-methyl imidazolium chloride

The heteropolyacids (HPAs) of H3PW12O40 (PW12) and H4SiW12O40 (SiW12) have been demonstrated to be effective catalysts for promoting dehydration of the fructose to 5-hydroxymethylfurfural (5-HMF) in the presence of the ionic liquid of 1-butyl-3-methyl imidazolium chloride ([BMIM]Cl) as green solvent. The 5-HMF can be obtained with both the yield and selectivity of 99% at 80 degrees C in only 5 min. The activation energy of 31.88 kJ mol(-1) by applying the [BMIM]Cl/PW12 system for dehydration of the fructose is much lower than those reported in the literature. Moreover, the used ionic liquid of [BMIM]Cl and HPAs could be recycled and reused with only slight decrease of reactivity for at least ten times. Compared with those systems reported so far, the [BMIM]Cl/PW12 and [BMIM]Cl/SiW12 exhibit higher yield, shorter reaction time, lower temperature for catalytic conversion of the fructose to 5-HMF, and they are environmental-friendly green systems. (C) 2014 Elsevier B.V. All rights reserved.