Perfect recycle and mechanistic role of hydrogen sulfate ionic liquids as additive in ethanol for efficient conversion of carbohydrates into 5-ethoxymethylfurfural

Hydrogen sulfate ionic liquid as co-solvent and homogeneous catalyst can promote efficient conversion of carbohydrates into 5-ethoxymethylfurfural (5-EMF). Yields of 5-EMF were as high as 77% and 43% from inulin and sucrose, respectively, in the mixed solvent system of ethanol-[BMIM][HSO(4)1 for 30 min reaction time at 130 degrees C. The ionic liquid could be perfectly recycled with a single pretreatment of activated carbon for 24 h. Based on the characterization with H-1 NMR and ATR-FTIR, the mechanism for the hydrogen sulfate ionic liquid promoted conversion of inulin into 5-EMF through stabilization of 5-hydroxymethylfurfural (5-HMF) with the C-2 hydrogen of the ionic liquid. Hydrogen sulfate ionic liquid as additive allows efficient conversion of carbohydrates into biofuels and as homogeneous catalysts, they can be easily reactivated and recycled with activated carbon treatment. (C) 2017 Elsevier B.V. All rights reserved.