氢键对水杨酸酸度影响的量子化学研究

A Quantum Chemistry Study on the Influence of Hydrogen Bond on the Acidity of Salicylic Acid

分子内氢键的形成影响羧酸的酸性,实验测定表明,水杨酸的酸性大约比苯甲酸强18倍,而其异构体——对羟基苯甲酸的酸性仅为苯甲酸的一半,已有文献从氢键形成角度定性讨论这一问题,我们采用CNDO/2法对其影响实质给予进一步的探讨,从微观角度阐述了该过程的可能机理,得到了与实验一致的结果。

The influence of intramolecular hydrogen bond and solvent water on the ionic dissociation of salicylic acid was studied by quantum chemistry CNDO/2 method. As a result of this study, we have drawn the total energy curve of the acid dissociating process and the figure of the mechanism of hydrogen migration. By discussing the charge distribution and analyzing the computing results with the energy decomposition method, we have explained the influence of hydrogen bond on the acidity of salicylic acid at the molecule and electron level.