Coordination of Acidic Deep Eutectic Solvent–Chromium Trichloride Catalytic System for Efficient Synthesis of Fructose to 5-Hydroxymethylfurfual

Development of an eco-friendly and effective reaction system for production of platform chemicals like 5-hydroxymethylfurfural (HMF) has always been a hot topic in biorefineries. In this study, the acidic deep eutectic solvents (DESs) coupled with chromium chloride (CrCl3) have been developed for effective conversion of fructose to HMF under a microwave-assisted manner. The acidic DES was composed of an organic acid and choline chloride (ChCl). Among the organic acids screened, the ChCl–HCOOH system was found to be the most effective medium for the HMF production, which was attributed to the smaller molecular structure and stronger acidity. Such an observation was also consistent with the larger interaction potential energy between fructose and ChCl–HCOOH obtained from the Monte Carlo simulation. In addition, a synergistic effect achieved from the ChCl–HCOOH/CrCl3 mixture played a vital role on the formation of HMF. The ChCl–HCOOH/CrCl3 system could be reutilized without remarkable change in HMF yield, indicating the advantages of ease of recovery and high catalytic stability.