大学化学 >> 2015, Vol. 30 >> Issue (1): 68-71.doi: 10.3866/PKU.DXHX20150114

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从无键共振看气相中醇的酸性顺序

王文峰, 袁耀锋   

  1. 福州大学化学学院 福建福州 350108
  • 发布日期:2015-02-25
  • 通讯作者: 王文峰 E-mail:wangwf@fzu.edu.cn
  • 基金资助:

    福建省自然科学基金(No.2013J01361)

The Acidity Sequence of Alcohols in Vapor Phase in Terms of No-bond Resonance

Wang Wenfeng, Yuan Yaofeng   

  1. College of Chemistry, Fuzhou University, Fuzhou 350108, Fujian, China
  • Published:2015-02-25

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摘要：

通过比较C—O单键和C=O双键的键能,预测醇的共轭碱很容易通过无键共振形成C=O双键。由于C—C键能远小于C—H键能,所以甲基比氢原子更容易通过形成无键共振来稳定烷氧基负离子,由此导致气相中的酸性顺序为:(CH3)3COH>(CH3)2CHOH>CH3CH2OH>CH3OH。这个观点得到了量子化学计算的支持。

关键词: 键能, 无键共振, 醇, 酸性顺序

Abstract:

By comparing bond energies of C—O single bond and C=O double bond, it can be predicted that the conjugate bases of alcohols are able to form C=O double bond via no-bond resonance. Since the bond energy of C—C single bond is much lower than that of the C—H single bond, methyl group is easier to stabilize alkoxide ions via no-bond resonance compared with H atom, the acidity sequence of alcohols in vapor phase is: (CH3)3COH >(CH3)2CHOH >CH3CH2OH >CH3OH. This viewpoint has been supported by the result of quantum chemistry calculation.

Key words: Bond energy, No-bond resonance, Alcohol, Acidity sequence