For the toluidine isomers, amino group acidity represents a characteristic feature of these compounds in their electric neutral state. As demonstrated by theoretical calculations based on the quantum chemistry composite G4 method and density functional theory, the CH acidity of the methyl group is hidden under NH acidity. The transformation of toluidines into their mono- and bi-oxidised states significantly increases the acidity of the methyl group. This study indicates that the presence or absence of these deprotonated species in reaction mixtures will determine the CN or CC coupling toluidine products. In agreement with published synthetic approaches for aniline dyes, such as mauveine and fuchsine, the results obtained explain the alternative reaction pathways occurring during the oxidation of toluidine isomers.

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关于甲苯胺异构体的 NH 和 CH 酸度：某些苯胺染料合成的理论描述和实际结果

对于甲苯胺异构体，氨基酸度代表了这些化合物在电中性状态下的特征。基于量子化学复合G4方法和密度泛函理论的理论计算表明，甲基的CH酸性隐藏在NH酸性之下。甲苯胺转化为单氧化态和双氧化态显着增加了甲基的酸度。该研究表明，反应混合物中这些去质子化物质的存在与否将决定 CN 或 CC 偶联甲苯胺产物。与已发表的苯胺染料（如紫红色和品红）的合成方法一致，所得结果解释了甲苯胺异构体氧化过程中发生的替代反应途径。