Efficient process for conversion of fructose to 5-hydroxymethylfurfural with ionic liquids

An efficient process for the dehydration of fructose into 5-hydroxymethylfurfural (5-HMF) in ionic liquid 1-butyl-3-methyl imidazolium chloride ([BMIM][Cl]) by using a sulfonic ion-exchange resin as catalyst was developed. A fructose conversion of 98.6% with a 5-HMF yield of 83.3% was achieved in 10 min reaction time at 80 °C. When the reaction temperature was increased to 120 °C, a 5-HMF yield of 82.2% was obtained in only 1 min for essentially 100% fructose conversion. No large decrease in 5-HMF selectivity occurred for initial fructose concentrations of up to 20 wt.%. Water content of up to 5% in the [BMIM][Cl] had no effect on the fructose conversion rate and 5-HMF yield, but water content higher than 5 wt.% led to lower conversions and yields. The ionic liquid and sulfonic ion-exchange resin could be recycled and exhibited constant activity for 7 successive trials. The proposed process of using an ionic liquid with ion-exchange resin catalyst greatly reduces the reaction time required over previous works for converting fructose to 5-HMF.