The effect of N-tetradecyl-N,N-dimethylamine oxide micelles on the kinetics of the electron transfer reaction of Ce(IV) with substituted malonic acids

Abstract

The kinetics of the oxidation of malonic acid and (its substituted compounds, methyl-, ethyl-, butyl- and benzyl-malonic acid) by ceric ions has been studied at 20.0 °C in the absence and the presence of the surfactant N-tetradecyl-N,N-dimethylamine oxide (C14DMAO). The addition of increasing amounts of C14DMAO influences the rate of the redox process to an extent that significantly depends on the hydrophobicity of the reducing species. The reactivity data together with the estimated binding constants and the standard transfer free energies of the malonic acids from water to the micelles suggest that the malonic acid is confined to the aqueous pseudo-phase while for the other solutes the binding occurs in the palisade layer of micelles. © 2009 Elsevier B.V. All rights reserved.