多种碳正离子的结构和稳定性问题的探讨

A Discussion on the Structure and Stability of Various Carbocations

采用DFT方法计算了多种普通碳正离子、烯丙基型碳正离子以及特别稳定的α-氨基和α-羟基碳正离子的结构和能量。结果表明,普通碳正离子依靠形成超共价结构、重排和超共轭效应获得稳定,烯丙基型碳正离子依靠共轭效应获得稳定。α-羟基和α-氨基碳正离子的稳定性特别高,分别相当于或高于环丙烯碳正离子。最后,本文还建议了氨基和羟基对碳正离子的不同稳定方式。

The structures and energies of various common carbocations,allylic carbocations,and particularly stableα-amino andα-hydroxyl carbocations were calculated using DFT(density functional theory).The results showed that common carbocations are stabilized by the formation of supercovalent structures,rearrangement,and superconjugation effects,whereas allylic carbocations are stabilized by conjugate effects.The stabilities ofα-hydroxyl andα-amino carbocations are particularly high and are equivalent to or higher than that of cyclopropylene carbocation.Finally,different methods of carbocation stabilization using amino and hydroxyl groups are suggested.