Solvation of protons in anhydrous H2SO4 as the main factor determining its superacidic properties

Research paper by V. B. Kazanskii, V. N. Solkan

Indexed on: 01 Jan '00Published on: 01 Jan '00Published in: Kinetics and Catalysis


The energies of solvation of H3SO4+ cations and HSO4- anions by a sulfuric acid molecule in the gas phase are calculated at the 6–31++G** level using the GAMESS program. The energy of additional solvation of the resulting complexes with liquid sulfuric acid was modeled within the framework of the PCM continuum model. The results obtained enable almost quantitative description of the energy of self-dissociation of 100% liquid sulfuric acid. The energy of proton solvation by 100% sulfuric acid calculated in a similar way was ∼20 kcal/mol lower than the heat of proton hydration in aqueous solutions. This result explains the superacidic properties of anhydrous H2SO4.