酸解離定数, 電子状態
An acid dissociation constant (pKa) is an index for quantitatively expressing the strength of the acid. The pKa values are used not only in the field of an organic chemistry, but also in various fields e.g., biology, pharmacodynamics, pharmaceutical design, and toxicity studies, etc.. This value is a very important physical quantity in dealing with the chemical substance. However, it is very difficult for predicting theoretically of the pKa value of the molecule with having a complicated structure. The purpose of this study is developing a new method for predicting the pKa value using the electronic theory. Strength of the acid is determined by the stability of the anionic structure when those molecules are deprotonated. In other words, if the anionic structure is stable, it means a much stronger acidity. In this study, by using the DV-Xα molecular orbital method about several acid molecules with the different of the value of pKa, it was compared the changes in the spatial distribution of the wave function during the process of the deprotonation.
