摘要:
本文以正丁醚/水和环己烷/水分配系数的对数差值A作为酸性指数,以氯仿/水和四氯化碳/水分配系数的对数差值B作为碱性指数来度量苯系物的Lewis酸碱性,阐明A,B两指数的物理意义,并表征其相互作用的lewis酸、碱间的分子作用力的大小.定量分析其与Kamlet等人提出的溶剂化显色参数π*,α,β间的关系,研究了各种分子间力对酸、碱性的相对贡献,氢键的贡献是主要的,其次是偶极作用的贡献,色散力引起的贡献很小以至可以忽略不计.比较研究显示该酸碱参数能够有效的代替溶剂化参数用于LSER研究之中.
Abstract:
A new approach to the quantification of the Lewis acidity and basicity of benzene and its derivatives was presented in this paper. The logarithm difference values of partition coefficients of the compounds in butyl ester/water and in cyclohexane/water system were used for the measurement of the Lewis acidity,while the logarithm difference values of partition coefficients in trichloromethane/water and tetrachloromethane/water system were used for the measurement of the lewis basicity. The physical meaning of the parameters A and B was then interpreted, which expressed the interaction magnitude of molecular force between Lewis acid and Lewis base. By means of quantitative analysis with the solvatochromic parameters π*,α,β it is found that there is a good correlation between them,which showed clearly the relative contribution of various molecular forces to Lewis acidity and basicity, that hydrogen bonding play a major contribution for Lewis acidity and basicity.while the inductive force is minor,and the contribution of dispersion is so small that can be neglected. Comparing with solvatochromic parameters,it is found that these parameters can be used in LSER research successfully.
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