Solubility of electrolytes in 1,2-dichloroethane and 1,1-dichloroethane, and derived free energies of transfer

The solubility of 27 1:1 electrolytes in 1,2-dichloroethane and 25 1:1 electrolytes in 1,1-dichloroethane has been determined. Combination of the solubility values with association constants, and correction for activity coefficients by the extended Debye–Huckel theory, yields standard free energies of solution of the ionic species (M++ X–). From like data in water, free energies of transfer from water to the dichloroethanes have been calculated and have been split into single-ion values through the assumption that ΔGt°(Ph4P+, Ph4As+)=ΔGt°(Ph4B–). It is shown that the free energy of anions (Cl–, Br–, I– and ClO4–) in the dichloroethanes is much higher in value than in water and in dipolar approtic solvents (DMSO, DMF and MeCN). The free energy of most cations (Na+, K+, Rb+, Cs+, Me4N+, Et4N+, Pr4N+ and Bu4N+) is also higher in value in the dichloroethanes than in the dipolar approtic solvents. Both anions and cations are invariably higher in free energy by ∼1 kcal mol–1 in 1,1-dichloroethane than in 1,2-dichloroethane. It is concluded that the (Ph4P+, Ph4As+)=(Ph4B–) assumption yields single-ion free energies of transfer to or from the dichloroethanes that are chemically reasonable.