Transfer and partition free energies of 1 : 1 electrolytes in the water–dichloromethane solvent system at 298.15 K

Abstract

Solubility data at 298.15 K for 1 : 1 electrolytes in dichloromethane are reported. The results are used for the calculation of the transfer free energies for these electrolytes from water to dichloromethane. These data are compared with partition free energies as obtained from distribution ratios of these electrolytes in the mutually saturated solvent system. Except for Et₄NCl, where large differences are observed between transfer and partition data, agreement between ΔG^°_t and ΔG^°_p values for 1 : 1 electrolytes in the water–dichloromethane solvent system is found. This finding leads to the conclusion that in the partition of 1 : 1 electrolytes in this solvent system, most of the ions are unhydrated in the dichloromethane phase. Single-ion ΔG^°_t values for five anions and nine cations based on the Ph₄As Ph₄B convention are calculated. Single-ion ΔG^°_t values derived from experimental data are compared with corresponding values derived from theoretical considerations. Discrepancies of ca. 1 kcal mol^–1 or higher are observed for some ions.