Conductivity of long chain quaternary ammonium electrolytes in cyclohexane

Abstract

This work investigates the conductivity of tetraalkylammonium tetraarylborates as a function of concentration in cyclohexane. Fluorination of the tetraarylborates is found to markedly affect the association of ions in solution and hence increase the conductivity by approximately an order of magnitude. The conductivity of these solutions is comparable with other solvent–electrolyte solutions commonly used for electrochemical investigations. These electrolytes have a pronounced effect upon solution viscosity and a decrease in molar conductivity with increasing electrolyte concentration is found to be mainly due to decreased ionic mobility, although there is some evidence for quadrupole formation with tetraphenylborate electrolytes. Measurement of nuclear Overhauser effects show that there is a change in the ion pair orientation when the phenyl rings of the tetraphenylborate anions are halogenated.