Abstract: The distribution of products from glucose catalyzed by extremely low sulfuric acid(≤0.1%)in ethanol and ethanol/co-solvent medium was investigated.The results showed that ethyl levulinate (EL) was the main product in the liquid with a yield of 40.46% under the reaction conditions of glucose concentration 20 g/L, reaction temperature 200 ℃, sulfuric acid concentration 0.1% and reaction time 120 min.The influence of nine kinds of ethanol/solvent system was compared, and the effect of using n-hexane as a co-solvent was further investigated.Moreover, the effect of using n-hexane as a co-solvent was investigated, and similar results of the distribution of products were obtained compared with the results in pure ethanol system.The addition of n-hexane could not increase the yield of EL effectively, but it can improve the concentration of intermediate of 5-ethoxymethylfurfural(EMF).It also can prevent EMF of further hydration to form EL.Ethyl glucoside(EG)was easily obtained from glucose with lower or higher reaction temperature accompanied with shorter reaction time.Increment of the reaction temperature and reaction time has positive effect on generation of EL.The byproducts, such as levulinic acid (LA)and 5-hydroxymethylfurfural(HMF), was accounting for a minority part of the product during the reaction process.According to the distribution of products, a reaction pathway for the extremely low sulfuric acid catalyzed conversion of glucose in ethanol/n-hexane medium was proposed.

Key words: glucose, ethyl levulinate, extremely low sulfuric acid, co-solvent