The solvation of fluoride ions. I. Free energies for transfer from water to aqueous alcohol and acetonitrile mixtures

The solubilities of NaF and LiF have been measured in mixtures of water with methanol, ethanol, ethylene glycol and acetonitrile over the whole composition range. Gibbs free energies of transfer of the fluoride ion from water to the mixed and pure solvents have been calculated from the solubility data via the tetraphenylarsonium tetraphenylborate assumption. The values so obtained indicate that the fluoride ion is preferentially solvated by water as a result of its strong hydrogen-bonding capabilities. Desolvation of the fluoride ion is especially marked in acetonitrile-rich solutions.