高等学校化学学报 ›› 1997, Vol. 18 ›› Issue (7): 1081.

• 论文 • 上一篇    下一篇

α-V、Ⅵ主族正离子取代的甲苯和苯乙酮系列中碳-氢键均裂及异裂能量的研究

程津培, 刘博, 鲁云, 米江林, 还振威   

  1. 南开大学化学系, 天津 300071
  • 收稿日期:1997-02-05 出版日期:1997-07-24 发布日期:1997-07-24
  • 通讯作者: 程津培, 男, 48岁, 教授.博士导师.
  • 作者简介:程津培, 男, 48岁, 教授.博士导师.
  • 基金资助:

    国家自然科学基金

Homolytic and Heterolytic C-H Bond Dissociation Energies of a-V (or Ⅵ)-Group Cation-substituted Toluenes and Acetophenones

CHENG Jin-Pei, LIU Bo, LU Yun, MI Jiang-Lin, HUAN Zhen-Wei   

  1. Department of Chemistry, Nankai University, Tianjin 300071
  • Received:1997-02-05 Online:1997-07-24 Published:1997-07-24

摘要: 合成了α-位有第V、Ⅵ主族元素杂正离子取代基的甲苯系列(1)和苯乙酮系列(2)共11个Ylide前体化合物,用重迭指示剂法首次测定了其在二甲亚矾(DMSO)溶剂中的酸性解离常数PKa,同时结合碳负离子(即Ylide)氧化电位的测定,通过热力学循环估测了它们的气相均裂键能(BDE). 根据这些PKa和BDE数据,对16个Ylide前体化合物的C-H键的均裂能和异裂能进行了比较,并讨论了a-杂正离子取代基对相关的Ylide和类-Ylide自由基的热力学稳定性的影响及结构效应.

关键词: PKa, 均裂键能, 热力学稳定性, Ylide, 自由基

Abstract: Eleven α-V (or Ⅵ)-group cation-substituted toluenes (1) and acetophenones (2)were synthesized.The equilibrium acidities (PKa) of these compounds were determined indimethyl sulfoxide solution by the "Overlapping Indicator Method" and the homolytic C-Hbond dissociation energies (BDE) were derived from a thermodynamic cycle combining PKawith oxidation potential of carbanion.The effects of the a-positively charged groups on thethermodynamic stabilities of sixteen Ylide carbanions and the corresponding Ylide-like radi-cals and the remote structral effect have been discussed.

Key words: PKa, Homolytic bond dissociation energy, Thermodynamic stability, Ylide, Radical

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