Oxidative degradation of L(+)arabinose by chromium(VI) in absence and presence of sodium dodecyl sulphate and TX-100 micelles

The chromic acid oxidation of L(+) arabinose in the absence and presence of surfactants has an induction period followed by autoacceleration. The rates of the oxidation have been determined spectrophotometrically. Due to precipitation, the effect of cetyltrimethylammonium bromide (CTAB) can not be studied whereas the oxidation rate increased with increase in sodium dodecyl sulphate (SDS) and octylphenoxypolyethoxy ethanol (TX-100, non-ionic) concentrations. Micellar catalysis has been traced to partitioning of the arabinose and chromic acid species between the aqueous and micellar pseudo-phases. Micellar binding/association constants and activation parameters were evaluated and discussed. A mechanism consistent with the results obtained is also proposed. The addition of ammonium, lithium and sodium bromides in SDS micelles resulted in rate decrease.