The dehydration of fructose to 5-hydroxymethylfurfural (HMF) was investigated in the presence of the Brönsted-Lewis acidic ionic liquids (ILs). It was found that IL (3-sulfonic acid)-propyl-triethylammonium chlorochrominate [HO3S-(CH2)3-NEt3]Cl-CrCl2 (molar fraction of CrCl2 x = 0.55) had a good catalytic performance with 93.4% yield of HMF. IL acid site played a more significant role than its Brönsted counterpart in the reaction, and a synergetic effect of Brönsted and Lewis acid sites enhanced IL catalytic performance. The reusability of IL was good which could be reused up to 5 times without apparent decrease in the yield of HMF.

Shi-Wei Liu, Shan-Shan Kong, Lu Li, Shi-Tao Yu, Fu-Sheng Liu and Cong-Xia Xie