Conductance studies of tetra-alkylammonium bromides in 2-methoxyethanol at 25 °C

Abstract

Conductance measurements are reported for six symmetrical tetra alkylammonium halides, R4NBr (R = ethyl to heptyl) and two ‘reference electrolyte’, viz. tetrabutylammonium tetrabutylborate (Bu4NBBu4) and tetrabutylammonium tetraphenylborate (Bu4NBPh4) in 2-methoxyethanol (ME) at 25 °C. The data have been analysed by the 1978 Fuoss conductance equation in terms of the limiting molar conductivity, Λ0, the association constant, KA, and the association distance, R. The limiting ion conductances have been determined from the appropriate division of the Λ0-values of Bu4NBBu4 and Bu4NBPh4. The results indicate that all these salts are highly associated in this solvent medium. The KA values are generally found to decrease with increasing cationic size from Et4N+ to heptyl4N+ but decreases sharply for Pr4NBr. The individual limiting ion conductance (λ0±) obtained separately from the two reference electrolytes are in good agreement with each other, suggesting that any one of them can be used as a reference electrolyte in ME. The Walden products and the Stokes radii of the ions have been evaluated. The values indicate that R4N+ ions are poorly solvated in this solvent medium.