Solvation of ions. XIX. Thermodynamic properties for transfer of single ions between protic and dipolar aprotic solvents

Abstract

Standard molar free energies, enthalpies and entropies of transfer of some uni-univalent electrolytes from water to methanol, N-methylformamide, formamide, dimethyl sulphoxide, N,N-dimethyl- formamide, propylene carbonate, sulpholane, N-methylpyrrolidone and acetonitrile are presented. They have been divided into the corresponding thermodynamic properties for single ions by means of extrathermodynamic assumptions. Changes in the chemistry of anions on transfer from protic to dipolar aprotic solvents are mainly a function of enthalpy changes. There is a substantial loss of entropy on transferring both anions and cations from water to non-aqueous solvents. Entropies of transfer can be interpreted in terms of ordering and disordering solvent molecules and a uniquely extensive water structure. Evidence for solvation of the first and second kind in water is presented. Enthalpies of transfer from water are exothermic for cations but endothermic for many anions.