Direct conversion of fructose-based carbohydrates to 5-ethoxymethylfurfural （EMF） catalyzed by Lewis acid in ethanol was investigated. It was found that BF3.（Et）20 was favorable for 5-hydroxymethylfurfural （HMF） etherification to EMF. BF3.（Et）20 combination with A1C13.6H20 with the molar ratio of 1 was an effective catalyst system for synthesis of EMF from fructose-based carbohydrates. 55.0%, 45.4% and 23.9% of EMF yields were obtained from fructose, inulin and sucrose under optimized conditions, respectively.
An efficient catalytic system consisting of vanadyl sulfate/sodium nitrite was disclosed previously for the oxidation of benzylic alcohols into aldehydes with molecular oxygen.However,the roles of catalyst components were not investigated.In this paper,we examined catalytic oxidation of benzyl alcohol as a model reaction,especially by infrared spectroscopy.The role of each component is discussed including nitrite,vanadyl,sulphate,and water.Sodium nitrite could be converted into nitrate and nitric acid.The vanadium(IV)could be smoothly oxidized into vanadium(V)under mild and acidic conditions without any organic ligands.The transformation of sulfate and bisulfate,the cessation of an induction period,and the oxidation of benzyl alcohol were closely interrelated.The multiple roles of water are discussed,including reduction of the induction period,participation in redox cycles of nitric compounds,deactivation of vanadium,and as a byproduct of oxidation.This study contributes to further development of aerobic oxidation using vanadium based catalysts.
