Twenty-five 2,2'-disubstituted N-phenylbenzenesulfonamides (2-X-C6H4SO2NHC6H4-Y-2') were synthesised and their purity checked by elemental analysis. This set of model substrates involved all possible combinations of methoxy, methyl, hydrogen, chloro, and nitro substituents. The dissociation constants of the sulfonamides were determined by potentiometric titration in methanol, pyridine, dimethyl sulfoxide, N,N-dimethylformamide, acetone, and acetonitrile. The dissociation constants pKHA obtained were correlated with various sets of substituent constants describing electronic and steric effects of the substituents, and the statistically treated data were used to discuss the contribution of the substituent effects in the dissociation and the difference between the effects transmitted from the two rings. A linear regression model explaining 99% of the variability of experimental data in all the solvents has been found and discussed. Moreover, the experimental data were also interpreted by the methods using latent variables, the principal component analysis (PCA) and conjugated deviation analysis (CDA), and two latent variables were shown to be statistically significant in the description of dissociation. The first obviously describes common action of electronic and steric effects of substituents; the other probably concerns a combined effect of substituent and solvent on the position of acid-base equilibrium.
二十五种2,2'-二取代N-苯基苯磺酰胺(2-X-C6H4SO2NHC6H4-Y-2')被合成,并通过元素分析检查其纯度。这组模型底物涉及甲氧基、甲基、氢、氯和硝基取代基的所有可能组合。苯磺酰胺的解离常数通过在甲醇、吡啶、二甲基亚砜、N,N-二甲基甲酰胺、丙酮和乙腈中的电位滴定确定。所得到的解离常数pKHA与描述取代基电子和立体效应的各种取代基常数相关联,统计处理的数据用于讨论取代基效应在解离中的贡献以及从两个环传递的效应之间的差异。已找到并讨论了一个线性回归模型,解释了在所有溶剂中实验数据变异性的99%。此外,实验数据还通过使用潜在变量的方法进行解释,主成分分析(PCA)和共轭偏差分析(CDA),并且显示两个潜在变量在描述解离中具有统计显著性。第一个明显描述了取代基的电子和立体效应的共同作用;另一个可能涉及取代基和溶剂对酸碱平衡位置的联合影响。