季铵盐型离子液体催化合成乙酸正丁酯

一步法制备了4种季铵盐型离子液体，并用FT-IR和¹H NMR表征结构。结果表明所合成的离子液体符合其理论结构；以它们为催化剂进行了乙酸正丁酯的合成研究，在相同条件下乙酸正丁酯的产率顺序为［Et₂NH₂］［HSO₄］>［Et₃NH］［HSO₄］>［n-Pro₃NH］［HSO₄］>［n-But₃NH］［HSO₄］，并且［Et₂NH₂］［HSO₄］和［Et₃NH］［HSO₄］与产物不互溶，而［n-Pro₃NH］［HSO₄］和［n-But₃NH］［HSO₄］与产物互溶，表明季铵盐离子液体的催化活性和极性都随阳离子链长度的增加而降低。以三乙胺硫酸为催化剂考察了反应时间、反应温度、醇酸摩尔比和离子液体用量对乙酸正丁酯产率的影响规律，结果表明：在n(正丁醇)∶n(乙酸)∶n(离子液体)=1∶2∶0. 25，反应时间8 h，反应温度 90℃的条件下乙酸正丁酯的产率达到81. 94%。采用减压蒸馏，除去离子液体相中的水、乙酸正丁酯和未反应的原料，将离子液体进行循环使用4次，结果表明乙酸正丁酯的产率没有明显下降，说明离子液体的稳定性和循环使用性较好。

Quarernary ammonium acidic ionic liquids as esterification catalyst for synthesis of n-butyl acetate

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.