Conversion of Glucose to 5-Hydroxymethylfurfural in Deep Eutectic Solvent of Choline Chloride-Chromium Chloride

5-Hydroxymethylfurfural (HMF) is a crucial biobased compound for synthesizing chemicals and biofuels, but the direct conversion of glucose to HMF suffers low yield and purification problems. In this paper, a cheap and efficient deep eutectic solvent (DES) of choline chloride-chromium chloride (ChCl-CrCl(3)middot6H(2)O) was developed to convert glucose and other carbohydrates to HMF. High HMF yields of 70.2, 78.6, 72.6, and 71.7% were achieved from glucose, fructose, high fructose corn syrup, and sucrose, respectively. The DES ChCl-CrCl(3)middot6H(2)O could be reused nine times without a significant loss of catalytic activity. In addition, a method was developed to regenerate humins-polluted DES. Combined with ultraviolet and visible spectrum data and density functional theory calculation, [Cr(H2O)(2)Cl(3)Ch](+) was identified as the active species in DES ChCl-CrCl(3)middot6H(2)O. This paper proposed a new effective system to convert carbohydrates to HMF. The discovery of active species provides a base for future studies on dehydration mechanisms.

Automated summary

In this study, a cheap and efficient deep eutectic solvent was developed for the conversion of glucose and other carbohydrates to 5-Hydroxymethylfurfural (HMF). The high HMF yields achieved from various carbohydrates make this system a promising method for HMF synthesis. The identification of the active species in the solvent provides a basis for future research on the dehydration mechanisms.