Collect. Czech. Chem. Commun. 1988, 53, 665-670

A contribution to gas phase ionization of para-hydroxybenzoic acid: An LCAO-MO-SCF treatment

Stanislav Böhm and Josef Kuthan

Department of Organic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6


By means of the ab initio MO calculations using the STO-3G basis set augmented with diffuse p functions accompanied by semi-empirical MNDO calculations, it is demonstrated that the carboxylic group ionization in the isodesmy (A), X = p-OH, is energetically preferred to the phenolic group ionization in the process (B). The reasons of the earlier incorrect interpretations regarding the gas phase acidity of p-hydroxybenzoic acid (a,s-II) are discussed.