A Comparative Study of Bu₄NBr, NaBPh₄, Ph₄PCl, and Ph₄AsCl in Water and Methanol at 25 °C: Partial Molal Volumes, Heat Capacities, and Viscosities

Abstract

The apparent molal volumes [Formula: see text] and heat capacities [Formula: see text] of Bu 4 NBr, NaBPh 4 , Ph 4 PCl, and Ph 4 AsCl have been measured in water and methanol at 25 °C in the concentration range 0.01–0.2 M. The viscosity of aqueous NaBPh 4 and Ph 4 AsCl have also been measured at 25 °C and in the same concentration range. Individual ionic values have been estimated for most of these properties. A comparison of these values for the quaternary ions BU 4 N + , [Formula: see text], Ph 4 P + , Ph 4 As + illustrates sizable differences in the solute–solvent interactions of alkyl and aryl substituted ions. Some specificity is also suggested in the solvation of the tetraphenyl ions, as shown by a comparison of the properties which should reflect directly the size of the ions [Formula: see text]and also in (H 2 O → CH 3 OH) transfer functions.