Preferential solvation of ions in mixed solvents—III. Conductance studies of some 1:1 electrolytes in N,N-dimethylformamide + methanol mixtures at 25°C.

Abstract Equivalent conductances of Bu 4 NNO 3 ,AgNO 3 and KI in methanol (MeOH) and those of Bu 4 NBPh 4 ,Bu 4 NNO 3 , Bu 4 NI, Agno 3 and KI in several N,N -dimethylformamide + methanol (DMF + MeOH) mixtures over the entire solvent composition range have been measured at 25°C.The conductance data in all the cases have been analysed by the Shedlovsky method.Evaluation of limiting ion conductances (λ 0 i ) and hence the solvated radii ( r i ) of ions in DMF + MeOH mixtures shows a homoselective preferential solvation of Bu 4 NBPh 4 , Bu 4 NNO 3 and Bu 4 NI with the cation Bu 4 N + and the anions Ph 4 B − , NO − 3 and I − all being selectively solvated by MeOH. AgNO 3 and KI, on the other hand, are heteroselectively preferentially solvated with Ag + and K + being preferentially solvated by DMF and NO − 3 and I − preferentially solvated by MeOH.