Quantitative Evaluation of Dissociation Mechanisms in Phenolphthalein and the Related Compounds

Abstract

Computational chemistry programs were evaluated as aids to teaching qualitative analytical chemistry. Computational chemical calculations can predict absorption spectra, thus enabling the modeling of indicator dissociation mechanisms by different computational chemical programs using a personal computer. An updated MNDO program among 51 programs was found to be the best predictor to explain the dissociation mechanisms of isobenzofuranones and sulfonephthaleins. Unknown dissociation constants were predicted from atomic partial charges instead of Hammett's constants.