1,3环己二烯与丙腈D-A反应机理研究

Study on D A Reaction Mechanisms of 1,3 Cyclohexa diene with Propionitrile

采用从头算方法在３－２１Ｇ基组上，对１，３环己二烯与丙腈ｄｉｅｌｓ－Ａｌｄｅｒ反应所有可能的反应通道进行了研究。该反应生成的ｅｘｏ和ｅｎｄｏ两种产物，它们各自存在两条分步途径和一条协同途径，共６条反应通道。计算研究表明，无论生成ｅｘｏ还是ｅｎｄｏ产物，最有利的途径为由丙腈的端位碳原子先进攻环上碳原子的分步过程。其生成两种产物的反应速控步骤的位垒分别为５０．１７和５０．６７ｋＪ／ｍｏｌ。表明ｅｘｏ和ｅｎｄｏ产物竟争生成。

Six possible Diels Alder reaction channels of 1,3 cyclohexa diene with propionitrile leading to two types of exo and endo products have been studied by using ab initio method at 3 21G level.The calculated results show that the favorite path for both exo and enso products is a stepwise process,in which the terminal carbon of propionitrile attacks the carbon in ring at the first step.The actibation barrers for the rate detdrmining steps to form exo and endo products are 50 17 and 50 67kJ/mol,respectively and the exo one is slightly lower than endo one.