Ion association and solvation behavior of tetraalkylammonium iodides in binary mixtures of dichloromethane + N,N-dimethylformamide probed by a conductometric study

• Published in: Physical chemistry chemical physics : PCCP 2010-11, Vol.12 (43), p.14534-14542
• Main Authors: Bhattacharjee, Arijit, Roy, Mahendra Nath
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c0cp00532k

Precise measurements on electrical conductances of tetraalkylammonium iodides, R 4 NI (R = n-butyl to n-heptyl), in different mass% (0-100) of dichloromethane (DCM) + N , N -dimethylformamide (DMF) at 298.15 K have been performed. Limiting molar conductances ( Λ 0 ), association constants ( K A ) and co-sphere diameter ( R ) for ion-pair formation in the mixed solvent mixtures have been evaluated using the Fuoss conductance-concentration equation. However, the deviation of the conductometric curves ( Λ versus √ c ) from linearity for the electrolytes in 100 mass% of DCM indicated triple ion formation, and therefore corresponding conductance data have been analyzed by the Fuoss-Kraus theory of triple ions. Limiting ionic molar conductances λ ± 0 have been calculated by the reference electrolyte method along with a numerical evaluation of ion pair and triple ion formation constants ( K P K A and K T ). The results have been interpreted in terms of ion-solvent interactions and structural changes in the mixed solvents. Precise measurements on electrical conductances of tetraalkylammonium iodides in different mass% (0-100) of dichloromethane (DCM) + N , N -dimethylformamide (DMF) at 298.15 K have been performed