Catalysis and inhibition of the iodide reduction of peracids by surfactants: partitioning of reactants, product and transition state between aqueous and micellar pseudophases

Abstract

A multiple micellar pseudophase model of kinetics in aqueous surfactant solutions is described. The model has been developed using the transition state pseudoequilibrium constant approach. The advantage of this approach is that no assumptions are made about the nature of the micelle pseudophases. The kinetics of the reduction of pernonanoic and 3-chloroperbenzoic acids by iodide in SDS, Brij-35 and Triton X-100 are reported. The results are used to obtain the micellar association constants of the peracids and also the apparent (virtual) micellar association constants of the transition states. These are compared with the micellar association constants of the parent acids, obtained by pH titration. The association constants are discussed in terms of micellar catalysis and inhibition. Ratios of association constants indicate the relationship between initial, transition and final states.