大学化学 >> 2023, Vol. 38 >> Issue (11): 267-275.doi: 10.3866/PKU.DXHX202303055

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多种碳正离子的结构和稳定性问题的探讨

王文峰(), 袁耀锋   

  • 收稿日期:2023-03-16 录用日期:2023-06-01 发布日期:2023-06-21
  • 通讯作者: 王文峰 E-mail:wangwf@fzu.edu.cn
  • 基金资助:
    教育部2022年度基础学科拔尖计划2.0研究课题(2022114)

A Discussion on the Structure and Stability of Various Carbocations

Wenfeng Wang(), Yaofeng Yuan   

  • Received:2023-03-16 Accepted:2023-06-01 Published:2023-06-21
  • Contact: Wenfeng Wang E-mail:wangwf@fzu.edu.cn

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摘要：

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。

关键词: 碳正离子, 超共轭效应, 超共价结构, 密度泛函理论计算

Abstract:

The structures and energies of various common carbocations, allylic carbocations, and particularly stable α-amino and α-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 of α-hydroxyl and α-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.

Key words: Carbocation, Hyperconjugation effect, Super covalent structure, DFT calculation