Micellar Effects upon the reactions of Complex Ions in Solution

Article abstract of DOI:10.1039/ft9908600507

The binding of the substrates cis-²⁺ (en = 1,2-diaminoethane, B = alkylamines, imidazole, N-methylimidazole) to the micillar surface of sodium dodecyl sulphate resulted in the retardation of their dissociative aquation rates, the effect being sensitive to the hydrophobicity of the nonlabile amine ligand B.A contrastingly small rate acceleration for the corresponding ethanolamine and propan-2-ol amine complexes was observed under similar conditions.Triton X-100 (0.02 <*> _T/mol dm^-3 <*> 0.1) had virtually no effect on the aquation rates of such complexes except for cis-²⁺, in which case a small rate retardation was also observed.The rates of base hydrolysis of the cobalt(III)substrates were strongly retarded by the anionic micelles of SDS; the neutral micelles of Triton X-100 were effective in decelerating the rate of base hydrolysis of the cyclohexylamine complex cis-²⁺ only.The pseudo-phase ion-exchange equilibrium model satisfactorily explained the binding of the cationic substrates to the anionic micellar pseudophase of SDS.The values of the ion-exchange equilibrium constant and the relative base hydrolysis rates (k^W/k^M) indicated that both micellar binding and retardation of hydrolysis are governed by hydrophobic and electrostatic interactions.

Full text of DOI:10.1039/ft9908600507

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