己内酰胺功能化离子液体的合成及其催化酯化性能的研究

Synthesis and Catalytic Esterification Performance of Caprolactam Task-Specific Ionic Liquids

以价格低廉的己内酰胺为原料,制备和表征了4种己内酰胺功能化离子液体:1-(3-磺丙基)己内酰胺硫酸氢盐([C3SO3HCP]HSO4)、1-(3-磺丙基)己内酰胺对甲苯磺酸盐([C3SO3HCP]PTSA)、1-(3-磺丙基)己内酰胺磷酸氢盐([C3SO3HCP]H2PO4)、1-(3-磺丙基)己内酰胺四氟硼酸盐([C3SO3HCP]BF4).以乙酸和乙醇的酯化反应考察4种酸性离子液体的催化活性,并与3种具有不同氮杂环的SO3H-功能化离子液体和浓硫酸相对照.结果表明:当n(C2H5OH)∶n(CH3COOH)=1∶1.5,催化剂[C3SO3HCP]HSO4用量为酸醇总质量的5%,反应温度80℃,反应时间6 h,酯收率可达93.8%,离子液体经真空干燥重复使用10次后,仍具有较高的催化活性,而且对奥氏体316 L不锈钢试样的腐蚀率不到浓硫酸的1/6.还考察了以[C3SO3HCP]HSO4为催化剂催化合成系列乙酯也获得了较高的酯收率,且离子液体均能与酯产物自动分相.与传统硫酸催化酯化相比,此类离子液体催化酯化具有生产成本低、过程清洁、腐蚀率低、使用周期长等优点,具有替代传统浓硫酸催化醇酸酯化反应的潜力.

Four kinds of caprolactam task-specific ionic liquids（TSILs）, 1-（3-sulfopropyl）caprolactam hydrogen sulfate, 1-（3-sulfopropyl）caprolactam p-toluene sulfonate, 1-（3-sulfopropyl）caprolactam phosphate sulfonate, 1-（3-sulfopropyl）caprolactam tetrafluoroborate, were prepared and characterized with low price caprolactam as raw material. The catalytic activities of these acidic ionic liquids were investigated by the esterification of acetic acid with ethanol and were compared with 3 kinds of SO3H-functionalized ionic liquids with different nitrogen heterocycles and concentrated sulfuric acid. The results showed that under the optimized conditions [n（C2H5OH）∶n（CH3COOH）=1∶1.5], catalyst amount of 5%（w） based on acetic acid and ethanol., reaction temperature 80 ℃ and reaction time 6 h）, the yield of ethyl acetate was up to 93.8%. The ionic liquids dried in vacuum till remained high activity after reused for 10 times, and the corrosion rates of the 316 L austenitic stainless steel plates immersed in the systems with these ionic liquids were less than one sixth of that with sulfuric acid. Finally, the yields of series of ethyl esters were also high with [C3SO3HCP]HSO4 as catalyst, and the ionic liquids can form split-phases with ester product. Compared with the traditional sulfuric acid catalytic esterification, catalytic esterification of such ionic liquid has the advantages of low production cost, clean process, low corrosion rate, long useage cycle, and has the potential of replacing the traditional sulfuric acid in catalytic esterification reaction.