Catalytic Conversion of Carbohydrates into 5‐Hydroxymethylfurfural by Germanium(IV) Chloride in Ionic Liquids

Abstract Direct conversion of carbohydrates into 5‐hydroxymethylfurfural (HMF) catalyzed by germanium(IV) chloride in ionic liquids has been investigated in search of an efficient and environmentally friendly process. Monosaccharides D ‐fructose and D ‐glucose, disaccharides sucrose and maltose, and even the polysaccharide cellulose were successfully converted into HMF with good yields under mild conditions (yield up to 92 % in 5 min in the case of fructose). The structure of ionic liquids, catalyst loading, reaction temperature and water content had noticeable effects on this catalytic system. Addition of 5 Å molecular sieves during the dehydration of glucose resulted in an increase in HMF yield from 38.4 % to 48.4 %. A mechanism for glucose conversion to HMF catalyzed by germanium(IV) chloride was proposed according to 13 C NMR spectra obtained in situ under different conditions using D ‐glucose‐2‐ 13 C as the substrate.