5-Hydroxymethylfurfural (HMF), a versatile intermediate from biomass, can be applied to prepare a wide range of valuable compounds in the petroleum and chemical industries. Thus, simple, fast, and practical methods to convert carbohydrates into HMF have been capturing increasing attention. We reported herein a method of using p-toluenesulfonic acid (p-TsOH) and Brønsted acidic ionic liquid as catalysts for the dehydration of fructose in dimethyl sulfoxide (DMSO) under a continuous flow process. The effect of the various reaction conditions on HMF formation was investigated, and the HMF yields were determined by the HPLC method. The results showed that p-TsOH and Brønsted acidic ionic liquid are effective catalysts within short residence times. This study provides a simple and safe procedure that can be potentially performed on a large scale to synthesize HMF from fructose.

The one-step dehydration/oxidation of fructose afforded 2,5-diformylfuran in excellent yield with high selectivity.