Thermodynamics of transfer of Ph4C; scaled-particle theory and the Ph4As+/Ph4B− assumption for single ions

Free energies of transfer of Ph 4 C from acetonitrile to 20 other solvents have been calculated from literature data. The contribution of the cavity term to the total free energy has been obtained from scaled-particle theory and Sinanoglu-Reisse-Moura Ramos theory. It is shown that there is little connection between the cavity term and the total free energy of transfer, and that there must be, in general, a large interaction term. If the latter is important for transfer of Ph 4 C, we argue that it must also be important for transfer of the ions Ph 4 As + and Ph 4 B − . Previous suggestions that the interaction term is zero for transfer of these two ions are thus seen to be unreasonable. We also show, for six solvents, that the interaction term for Ph 4 C is very large in terms of enthalpy and entropy, and that scaled-particle theory seems not to apply to transfers of Ph 4 C between pure organic solvents.The free energy, enthalpy, and entropy of transfer of Ph 4 As + = Ph 4 B − have been calculated by dividing the total transfer values into neutral and electrostatic contributions; reasonable agreement is obtained between calculated and observed values.