Separation of viscosity B coefficients into ionic contributions. Part 1.—Tetrabutylammonium tetrabutylborate and tetraphenylphosphonium tetraphenylborate in dimethylsulphoxide

Abstract

The relative viscosities and densities of solutions of tetrabutylammonium tetrabutylborate, tetrabutyl-ammonium bromide, tetraphenylphosphonium tetraphenylborate and tetraphenylphosphonium bromide in dimethylsulphoxide have been measured at 25 and 35 °C. Viscosity B coefficients and apparent molar volumes at infinite dilution have been determined for these salt systems. Two independent values of the viscosity B coefficient for the bromide ion have been obtained with the aid of van der Waals volumes for the various ionic species. A new set of ionic B coefficients for the alkali-metal halides in dimethylsulphoxide have been calculated and compared with the results of earlier work. A generalised division of the ionic B coefficient into contributory factors is proposed and applied to some of the results. Ion–solvent interactions are also discussed in terms of the transition-state treatment of viscous flow.