Conductance of 1∶1 electrolytes in methyl acetate

The electrolytic conductances of NaClO₄, NaB(C₆H₅)₄, (n-C₄H₉)₄NClO₄ and (n-C₄H₉)₄NPF₆ have been measured in methyl acetate at 25°C. A dominating feature of these electrolyte solutions is, as expected, strong ion pairing. In addition it is found that the formation of triple ions makes an important contribution to the overall molar conductivities. The data suggest that there are strong ion-solvent interactions leading to structure-enhanced (after Diamond) ion association and triple ion formation which has an exact analogy in the phenomena of salting-in. The effects of increasing solution permittivity and viscosity are discussed, particularly in regard to comparing two models of treating conductivity data. The first model includes ion pairs and triple ions, and the second model ignores triple ion formation ascribing the anomalous increase in molar conductivities to a decrease in the ion association equilibrium constant caused by increasing solution permittivity.