Comparison of quantum chemical parameters and Hammett constants in correlating pKa values of substituted anilines
Comparison of quantum chemical parameters and Hammett constants in correlating pKa values of substituted anilines
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DOI：
10.1021/jo010234g
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发表时间：
2001-10-19
影响因子：
3.6
通讯作者：
Politzer, P
中科院分区：
文献类型：
--
作者：
Gross, KC;Seybold, PG;Politzer, P
历史上，Hammett常数在描述取代基对化学反应性和其他物理和化学性质的影响方面非常有效，而从量子化学计算得出的变量通常不太有效。以取代苯胺的实验pK（a）s为代表的物理化学性质，比较了5个从头算量子化学指标作为pK（a）的单参数回归描述符的有效性.所有测试的描述符表现良好的一组19个单，13个二，和4个三取代苯胺，和两个表现略好于传统的Hammett西格玛常数。在计算的量中，苯胺pK（a）s的最佳表示是由分子表面上的最小平均局部电离能产生的。
Historically, Hammett constants have been extremely effective in describing the influence of substituents on chemical reactivity and other physical and chemical properties, whereas variables derived from quantum chemical calculations have generally been less effective. Taking the experimental pK(a)s of substituted anilines as a representative physicochemical property, five ab initio quantum chemical indices are compared for effectiveness as one-parameter regression descriptors for pK(a). All of the tested descriptors performed well for a set of 19 mono-, 13 di-, and 4 trisubstituted anilines, and two performed somewhat better than the traditional Hammett sigma constants. Among the calculated quantities, the best representation of the aniline pK(a)s is produced by the minimum average local ionization energy on the molecular surface.