Kinetic Analysis for the Conversion of Fructose to 5-Hydroxymethylfurfural in 1-Butyl-3-methylimidazolium Chloride with Lower Water Contents

Abstract

Conversion of fructose to 5-hydroxymethylfurfural (HMF) was conducted in an ionic liquid (IL), 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), with low-to-middle (≤ 0.03‒10%) water contents at 100°C with p-toluenesulfonic acid as a catalyst. When fructose was mixed with [BMIM]Cl to start the reaction, fructose dissolved much faster and more rapidly converted to HMF in [BMIM]Cl with a low water content than it did in that with a middle one, suggesting that the conversion rate greatly depended on the said water content. HMF was stable in pure [BMIM]Cl at 100°C, and there were few possibilities for its rehydration and decomposition to byproducts. Based on these results, we proposed an autocatalytic model of the reaction that considers the effects of water; the formation of HMF was certainly affected by the water produced during the conversion. The kinetic analysis based on this model well expressed the formation of HMF in the IL with a low water content.