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本文利用同位素取代法考察了离子液体催化苯与烯烃烷基化反应机理.首先进行了Et3NHCl-AlCl3催化氘代苯与1-十二烯烃的反应,通过GC-MS及NMR分析产物结构,根据分析结果,在反应过程中一个D原子从苯环转移到侧链的1-碳.由此推断离子液体催化苯与长链烯烃的烷基化反应机理为:反应由Lewis酸AlCl3引发;AlCl3吸引1-十二烯烃的π电子向1-碳转移,形成碳正离子;碳正离子进一步与苯反应形成不稳定的σ络合物,σ络合物苯环上的sp3杂化碳相连的D+转移到侧链的负电1-C上取代AlCl3,生成产物2-十二烷基苯.
In this paper, the mechanism of alkylation of benzene with olefins catalyzed by ionic liquid was investigated by using isotopic substitution method. The reaction of deuterated benzene with 1-dodecene was catalyzed by Et3NHCl-AlCl3. The product structure was analyzed by GC-MS and NMR. As a result, one D atom was transferred from the benzene ring to the 1-carbon of the side chain during the reaction.It was concluded that the mechanism of alkylation of benzene with long-chain alkene by ionic liquid was as follows: the reaction was initiated by Lewis acid AlCl3; AlCl3 attracted 1 - dodecene π-electron transfer to the 1-carbon, the formation of carbon positive ions; carbon positive ions further react with benzene to form unstable σ complex, σ complex benzene ring sp3 hybrid carbon linked D + transfer Substituting AlCl3 for the side-chain negatively charged 1-C yields the product 2-dodecylbenzene.