Free energies of transfer of ions from water to butan-1-ol

Abstract

The solubilities of 30 1:1 electrolytes in butan-1-ol are reported. Combination of these data and ion-pair association for the electrolytes in butan-1-ol yield solubility (ion-activity) products from which free energies of solution of the ionic species M⁺+ X^– have been calculated. Using the corresponding data in water, the free energies of transfer of M⁺+ X^– from water to butan-1-ol are obtained.

Single-ion free energy of transfer values for 12 cations and 5 anions were calculated by using Parker's convention. These results are compared with those obtained previously for transfer to methanol, ethanol and propan-1-ol.

For the single ions, an increase in the free energy of transfer is observed along the series of alcohols. The hydrophobic ions, however, do not show a regular pattern with regard to their free energy of transfer.

Single-ion partition coefficients from pure water to the pure solvent have been calculated, and the implications of these data on the extraction of M⁺+ X^– from water to butan-1-ol are discussed.