A facile acidic choline chloride–p-TSA DES-catalysed dehydration of fructose to 5-hydroxymethylfurfural

Abstract

The conversion of lignocellulosic biomass to biofuel precursors has recently been a focus of intensive research due to the essential role of biofuels as transport fuels in the future. Specifically, the conversion of fructose to 5-hydroxymethylfurfural (5HMF) has gained momentum, as 5HMF is a versatile bio-based platform molecule that leads to a plethora of high-value chemicals and biofuel molecules, such as DMF. Herein, we report the use of an environmentally friendly, Brønsted acidic, deep eutectic mixture consisting of choline chloride (ChCl) and p-TSA for the dehydration of fructose to 5HMF. Unlike previous systems, the use of ChCl–p-TSA plays a dual role, as both a hydrogen bond donor (HBD) and a catalyst for the dehydration reaction, thus obviating the addition of an external acid. The reaction was examined and optimised in a batch system, where it was found that fructose was readily dehydrated to 5HMF. The best reaction conditions, with the highest 5HMF yield of 90.7%, were obtained at a temperature of 80 °C using a DES molar mixing ratio of 1 : 1 ChCl : p-TSA and feed ratio of 2.5%, and with a reaction time of one hour.