Benzenethiols: pK a Values Measured in Solutions Against Quantum Chemically Computed Gaseous-Phase Proton Affinities

By the PM3 method, standard entropies, heats, and free energies of formation have been computed for 27 benzenethiols and anions formed at their heterolytic dissociation. The enthalpies and free energies of proton affinity (PA) for the benzenethiolate anions have been calculated. It has been found that the benzenethiols' pK a quantities measured by different authors in water-acetone, water-ethanol, and methanol media correlate linearly with the PA values. The dependences established allow one to a priori predict the protolytic properties of the benzenethiol series compounds.