Preparation and catalytic properties of 1-(3-sulfonic group) propyl-3-methyl imidazolium phosphotungstate

A novel environmental friendly catalyst, 1-(3-sulfonic group) propyl-3-methyl imidazolium phosphotungstate ([MIMPS]₃PW₁₂O₄₀) for synthesis of 2-butoxyethyl acetate (BAC) from 2-butoxyethanol and acetic acid was prepared from N-methylimidazolium, 1,3-propanesultone and phosphotungstic acid by a two-step method and was characterized by XRD, FTIR and TG-DSC. The [MIMPS]₃PW₁₂O₄₀ catalyst existed in Keggin structure, possessed eight molecules of crystalline-water and was thermally stable. Under the optimum reaction conditions for synthesis of BAC: reaction temperature 120°C, reaction time 2.0 h, mole ratio of 2-butoxyethanol to acetic acid 1.2:1, mass ratio of catalyst to reactants 0.04and mass ratio of cyclohexane as water entrainer to reactants 0.3, the yield of BAC was 99.3%. The catalyst could be separated easily. After the catalyst was reused 9 times, yield of BAC remained at 86.8%. The product was identified by FTIR and no any by-product was observed.