Solvation of Some Tetraalkylammonium Salts Investigated Conductometrically and Viscometrically in Binary Mixtures of Acetonitrile + Methanol at 298.15 K

Abstract

Abstract Molar conductances and viscosities of some tetraalkylammonium perchlorate salts (R4NClO4 where R=methyl, ethyl, propyl, butyl) have been measured in the concentration range (30–500)×10−4 M in the binary mixtures of acetonitrile (AN)+methanol (MeOH) containing 0, 20, 40, 60, 80 and 100 mol% methanol at 298.15 K. Conductance data was analyzed by the Shedlovsky equation and the viscosity data by Jones–Dole equation. The limiting ionic conductances (λ o ±) were used to calculate the solvated radii (r i ) of the ions. The A and B coefficients of the Jones–Dole equation are positive in all salts. The A coefficients are in reasonably good agreement with the limiting theoretical values (Aη) calculated using Falkenhagen–Vernon equation. The variation of the actual solvated radii (r i ) as well as the ionic B ± coefficients with solvent composition in AN+MeOH mixtures shows the preferential solvation of tetraalkylammonium ions by methanol-rich region of the mixtures. The extent of solvation of the tetraalkylammonium ions is in the order Me4N+>Et4N+>Pr4N+>Bu4N+.