Four kinds of quaternary ammonium ionic liquid were prepared by one-step method. The IR and 1H NMR spectra showed that their structures were in accordance with their theoretical structure. n-Butyl acetate was synthesized with acetic acid and  n-butyl alcohol catalyzed by the 4 kinds of ionic liquids prepared under the same conditions. Their catalytic activity sequence was ［Et2NH2］［HSO4］>［Et3NH］［HSO4］> ［n-Pro3NH］［HSO4］［n-But3NH］［HSO4］

［Et2NH2］［HSO4］and ［Et3NH］［HSO4］were immiscible with the product

［n-Pro3NH］［HSO4］and ［n-But3NH］［HSO4］were miscrible with the product

the result showed the catalytic activity and polarity of ionic liquids were related to their cation structure

especially the chain length of the cation

both the catalytic activity and polarity of the ionic liquids were getting lower with the chain length increasing. The effects of reaction time

reaction temperature

molar ratio of n-butyl alcohol to acetic acid and catalyst dosage on the yield of n-butyl acetate were investigated when ［Et3NH］［HSO4］was selected as the catalyst of esterification reaction. Under the conditions of molar ratio of n(n-butyl alcohol):n(acetic acid)∶n(［Et3NH］［HSO4］) =1∶2∶0.25

reaction temperature 90℃ and reaction time 8 h

the yield of n-butyl acetate reached to 81.94%。After removal of water

n-butyl acetate and unreacted raw materials by vacuum distillation

the ionic liquid was recovered and reused 4 times

the yield of n-butyl acetate did not decreased markdely

it showed that the ionic liquid was stable during the reaction and could be reused.