Selective HMF synthesis from glucose via microwave-assisted metal chloride catalysis

Microwave-assisted heating technology is considered to be a novel catalytic method. In this study, the microwave method was combined with the low-toxic metal chloride catalyst AlCl3 and the green solvent GVL, to directly catalyze the conversion of glucose to HMF with the assistance of the microwave. Under the optimized reaction conditions, the ratio of water to organic phase GVL was 4:6 as the solvent, and the yield of HMF was 74.04 % when the mixture was reacted for 10 min under 220 W microwave power. Using H2O and GVL as solvents, the obtained reaction solution will be divided into an aqueous layer and an organic layer. The catalyst AlCl3 mainly exists in the aqueous layer, and the product HMF is mainly distributed in the organic layer. This facilitates the separation of HMF and the recycling of the catalyst. This work highlights an efficient and environmentally friendly reaction system, which is expected to provide ideas for the preparation of HMF on an industrial scale.