Conductance behavior of 1∶1 electrolytes in N,N-dimethylmethanesulfonamide

The conductances of eleven 1:1 salts have been measured at 50°C in N,N-dimethylmethanesulfonamide (DMMSA) for electrolyte concentrations of 1.2–55.0×10^–4 mol-dm^–3. The conductance data were analyzed using the equation of Lee and Wheaton. Calculations for different values of the distance parameter R indicate that all salts studied are only slightly associated in DMMSA. Association was somewhat greater for the trimethylphenylammonium halides than for the tetraalkylammonium salts. Ionic limiting molar conductances were estimated using the tris (isopentyl) butylammonium tetraphenylborate approximation. The markedly smaller value for _o (Na⁺) compared to the values for _o (Br^–) and _o (I^–) indicates that the sodium ion is probably more extensively solvated than the halide ion. In general, it appears that DMMSA (dielectric constant=80.31 at 50°C) is similar in its solvent properties to dipolar aprotic heterocyclic solvents such as 2-cyanopyridine and 3-methyl-2-oxazolidone which have similar dielectric constants.