Kinetic treatment of the reaction of m-chloroperbenzoic acid and iodide in mixed anionic/non-ionic micelles

Abstract

Catalysis and inhibition of the title reaction in mixed micelles of Brij-35 and SDS is described. The kinetics are treated using a combined multiple micellar pseudophase model and transition state pseudoequilibrium constant approach that was previously used for the catalysis and inhibition of the reaction of peracids and iodide in non-ionic and anionic micelles, respectively (D. M. Davies, N. D. Gillitt and P. M. Paradis, J. Chem. Soc., Perkin Trans. 2, 1996, 659). In the present mixed micellar system the following factors are taken into account: (i) the mole ratio of the surfactants in the mixed micelle, which is the relevant quantity for the micellar kinetics and is different from the stoichiometric mole ratio of the surfactants; (ii) non-ideal mixing of the surfactants, which also influences the composition of the mixed micelle; (iii) the ideal behaviour of the apparent molar volume of micellized surfactant in mixed micelles; and (iv) deviations from ideality of the partitioning of reactants and transition state between mixed micelles and the bulk aqueous phase. Logarithms of micellar association constants of the reactants and transition state in the two surfactants have been obtained, together with parameters closely related to the excess Gibbs function associated with the deviations from ideality described by (iv). The relationship between the parameters that describe non-ideal mixing of the surfactants in (ii) and the deviations from ideality in (iv) is discussed.