Collect. Czech. Chem. Commun. 1980, 45, 2201-2214

Quantum-chemical study of dissociation of meta and para substituted benzoic acids at all-valence-electrons level

Ivan Danihela and Josef Kuthanb

a Department of Organic Chemistry and Biochemistry, Šafárik University, 041 67 Košice
b Department of Organic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6


Relative differences of electronic energies of meta and para substituted benzoate anions II and the parent acids I have been correlated with the substituent empirical parameters type σ and with pKX values of ionization of the acids I. The energies obtained by the EHT method only give linear correlation in the para substituted series of the studied compounds, whereas the analogous CNDO/2 energies lead to homogenous correlation for both meta and para substituents X. Effects of π and σ electrons are discussed as well as effects of electronic repulsion and attraction on the resulting microscopic substitution effect.