A theoretical study of the effect of the substituent Z on the gas phase acidity of substituted benzoic acids ZC6H4COOH in terms of density functional theory descriptors (chemical potential, softness and Fukui function) is presented. The calculated gas phase ΔacidG° values obtained were close to the experimental ones reported in the literature. The good relationship between the ΔacidG° values and the electronegativity of ZC6H4COOH and its fragments, suggested a better importance of the inductive than polarizability contributions. The balance of inductive and resonance contributions of the substituent in the acidity of substituted benzoic acids showed that the highest inductive and resonance effects were for the -SO2CF3 and -NH2 substituents in the para- and ortho-position, respectively. The Fukui function confirmed that the electron-releasing substituent attached to the phenyl ring of benzoic acid decreased the acidity in the trend ortho > meta > para, and the electron-withdrawing substituent increased the acidity in the trend ortho < meta < para.

中文翻译：

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使用密度泛函概念分析取代苯甲酸的气相酸度

根据密度泛函理论描述符（化学势、柔软度和福井函数），对取代基 Z 对取代苯甲酸 ZC6H4COOH 气相酸度的影响进行了理论研究。获得的计算气相ΔacidG°值接近文献中报道的实验值。ΔacidG° 值与 ZC6H4COOH 及其碎片的电负性之间的良好关系表明，感应贡献比极化率贡献更重要。取代基对取代苯甲酸酸度的感应和共振贡献的平衡表明，最高的感应和共振效应分别发生在对位和邻位的 -SO2CF3 和 -NH2 取代基上。