Ion-pair formation and walden product of some s-alkylisothiouronium salts in non-aqueous solvents at 25°C

Abstract

Precise conductance measurements have been made on 11 s-alkylisothiouronium salts in dimethylformamide at 25±0.02°C. The experimental data have been analysed on the basis of Fuoss' equation [R. M. Fuoss, J. Phys. Chem. Ithaca 79, 525 (1976), correction p. 1893, ibid. 81, 1529 (1977). Proc. Natl Acad. Sci. USA 77, 34 (1980)] using the NEW SCAN and R-PRESET programs. The parameters Λ 0, K A and R have been calculated for each salt. Single anionic conductances (Br −, I − and Pi −) in both DMF and DMSO were determined using the newly developed method [H. Sadek and A. M. Hafez, Electrochim. Acta 21, 767 (1976)]. The validity of the suggested equation [H. Sadek and A. M. Hafez, Pak. J. Sci. Res. 33, 24 (1981)] which relates the Walden product with the reciprocal molecular weight is proved for electrolytic solutions in dipolar aprotic solvents. Finally cationic conductances are recorded in both DMF and DMSO at 25°C and were found to decrease as cationic size increases.