离子液体催化苯与十二烯烷基化的反应机制的研究

Reaction Mechanism of Benzene Alkylation with 1-Dodecene Catalyzed by Chloroaluminate Ionic Liquid \Cl-AlCl_(3)

采用酸性氯铝酸盐室温离子液体[BMIM]Cl-AlCl3为催化剂,进行了苯与1-十二烯烷基化反应机制相关信息的实验研究. 结果表明,与AlCl3和HF催化不同,碳链重排在0～5.0℃时未被抑制;异构体的分布随温度的变化幅度不大;产物中内异构体的比例仍占优势;在5.0～75.0℃实验温度范围内没有显现烷基化产物的异构化作用. 据此推断,反应仍遵循碳正离子机理,碳链重排速率大于亲电取代的烷基化过程速率,不同异构体的生成反应可视作平行反应.

Reaction scheme information for alkylation of benzene with 1-dodecene was investigated using the \Cl-AlCl_(3) room temperature ionic liquids synthesized in our laboratory as biphasic catalysts. The experimental results show that the rearrangement of alkyl chain is not prohibited within 0~5℃ compared with AlCl_(3) and HF catalysis. The predominance of rearranged products indicates that the alkyl carbonium ion is formed. Besides, the isomerization of products is not detected in the temperature range of 0~75℃. It is believed that the reaction proceeds by way of carbonium ions mechanism. Moreover, the rate of alkyl rearrangement is faster than that of electrophilic alkylation between benzene and carbonium ions. Thus, the formation of different isomers from 2-to 6-LAB can be regarded as parallel reactions.