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正碳离子是重要的有机化学反应中间产物,而氢原子移位则是正碳离子异构化的主要反应途径。本文利用量子化学方法对丙基伯正碳离子和仲正碳离子的结构和生成热进行了研究,优化了丙基伯正碳离子和仲正碳离子的结构,计算得到了这两种正碳离子的能量。结果表明,丙基伯正碳离子的生成热为214.4kcal/mol,丙基仲正碳离子的生成热为197.3kcal/mol,伯正碳离子的生成热比仲正碳离子的生成热高17.1kcal/mol,表明丙基伯正碳离子能够通过氢原子移位转变为丙基仲正碳离子。以丙基伯正碳离子和仲正碳离子的结构为起点进行过渡态搜索,得到了丙基伯正碳离子通过氢原子移位转化为丙基仲正碳离子,从而进行正碳离子重排反应的过渡态,并通过振动方式分析,对过渡态进行了确认。计算得到的丙基正碳离子通过氢原子移位进行重排反应的能垒为3.5kcal/mol,表明丙基伯正碳离子很容易转化为仲正碳离子。
Carbanion is an important intermediate of organic chemical reaction, while hydrogen atom shift is the main reaction pathway of isomerization of carbon ion. In this paper, the structures and the heats of propyl primary carbon and secondary carbon are studied by quantum chemical method, and the structures of propyl primary carbon and secondary carbon are optimized. The two kinds of carbon Ion energy. The results showed that the progenitive heat of propycalcium ion is 214.4 kcal / mol and the progeny of propyric carbon ion is 197.3 kcal / mol. The heat of formation of primary cations is 17.1 kcal / mol, indicating propyl pristine carbon ions can be shifted by hydrogen atoms into propyl n-carbon ions. A transition state search was carried out starting from the structure of propyl basic carbon and quaternary carbon ions to obtain the ortho-carbon rearrangement of propyl primary carbon ions by the shift of hydrogen atoms to propyl secondary carbon ions Reaction transition state, and by vibration analysis, the transition state was confirmed. The calculated energy barrier for rearrangement of propyl-carbon ions by hydrogen atom shift is 3.5 kcal / mol, indicating that propyl primary-carbon ions can easily be converted into meta-carbon ions.