关键词: 季铵盐型离子液体, 酯化反应, 乙酸正丁酯

Abstract: 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.

Key words: quarernary ammonium acidic ionic liquids, esterification, n-butyl acetate