Free energies of transfer of some single ions from ethylene glycol to its isodielectric mixtures with acetonitrile at 25 °C

Free energies of transfer (ΔG t 0 ) of the reference electrolyte Ph 4 AsBPh 4 (Ph = phenyl) from ethylene glycol to its approximately isodielectric mixtures with acetonitrile have been determined at 25 °C from the measurement of the solubilities of KPi, Ph 4 AsPi, and KBPh (Pi = picrate) in these solvents. Using the assumption values for the individual ions K + , Pi − , Ph 4 As + , and Ph 4 s − have been estimated. These, in conjunction with previously determined values of ΔG t 0 for MCl (M = Li, Na, K, Rb, Cs, and H), KBr and KI have provided ΔG t 0 values for Cl − , Br − , I − , and M + ions. Ionic ΔG t 0 's have been interpreted in terms of specific ion-solvent interactions. The contrasting behaviour of ethylene glycol and acetonitrile in ion-solvation is shown to be characteristic of the protic and dipolar aprotic solvent types respectively.