Kinetics and Mechanism of Oxidation of D-Penicillamine by Potassium Hexacyanoferrate(III) Ions in Aqueous Solution in the Presence of Sodium Dodecyl Sulphate and Cetyltrimethylammonium Bromide

The effect of cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulphate (SDS) on the rate of oxidation of D-penicillamine by alkaline hexacyanoferrate(III) has been studied by spectrophotometrically at different temperatures. The effect of CTAB and SDS on the rate of reaction has been observed at even below the critical micelle concentration (CMC) of the surfactants, indicating binding of the substrate with the surfactants. On the basis of the kinetic results, the mechanism of the reaction has been proposed. The kinetic data have been rationalized in terms of Manger and Portnoy's model for micellar inhibition and binding parameters (viz. binding constants, partition coefficient, free energy transfer from water to micelle, etc.); activation parameters have also been evaluated.