%0 Journal Article
%T Kinetic Treatment of the Reaction of Fructose and N-Bromosuccinimide in Cationic/Anionic/Nonionic Micelles
%A Minu Singh
%J Journal of Soft Matter
%D 2014
%R 10.1155/2014/791563
%X The kinetics of oxidation of fructose by N-bromosuccinimide in acidic medium in the absence and presence of cationic, anionic, and nonionic surfactants has been measured iodometrically under pseudo-first-order condition. The oxidation kinetics of fructose by N-bromosuccinimide shows a first-order dependence on N-bromosuccinimide, fractional order dependence on fructose, and negative fractional order dependence on sulfuric acid. The kinetics is treated using Berezin¡¯s micellar model that was previously used for the catalysis and inhibition of the reaction. The determined stoichiometric ratio was 1£¿:£¿1 (fructose£¿:£¿N-bromosuccinimide). The variation of Hg(OAC)2 and succinimide (reaction product) has insignificant effect on reaction rate. Effects of surfactants, added acrylonitrile, added salts, and solvent composition variation have been studied. Activation parameters for the reaction have been evaluated from Arrhenius plot by studying the reaction at different temperatures. The rate law has been derived on the basis of obtained data. A plausible mechanism has been proposed from the results of kinetic studies, reaction stoichiometry, and product analysis. 1. Introduction It is well known that aqueous charged interphases play an important role in the enhancement of the rate of chemical reactions [1¨C5]. Micelles act as microreactors which both speed and inhibit the rates of a wide variety of uni- and bimolecular reactions and shift the equilibrium constants of many indicators [6¨C15]. Aggregate effects on chemical reactivity are generally interpreted by using pseudophase models which treat micelles and water as separate reaction media, that is, separate phases or pseudophases. This approach has been successfully applied to a wide range of chemical reactions in micellar solution, including mixed micelle, and in other types of association colloids, such as microemulsions and vesicle. Surfactant aggregates affect chemical reactivity primarily by binding or excluding reactants and only secondarily by changing the free energy of activation [16¨C19]. Considerable attention has centred on N-bromosuccinimide (NBS) because of its versatile behaviour as mild oxidant, halogenating agent, and N-anions, which acts both as bases and nucleophiles. NBS is well-known analytical reagent, and the mechanistic aspects of its reactions have been documented [20¨C25]. As a part of our mechanistic studies of oxidation of substrate by the NBS, I report the kinetics of oxidation of D-fructose by NBS in the micellar region. Fructose, or fruit sugar, is a simple monosaccharide found in
%U http://www.hindawi.com/journals/jsmat/2014/791563/