Micellar catalysis on picolinic acid promoted hexavalent chromium oxidation of glycerol

Under pseudo-first-order conditions, monomeric Cr(VI) was found to be kinetically active in the absence of picolinic acid (PA), whereas in the PA-promoted path, the Cr(VI)–PA complex undergoes nucleophilic attack by the substrate to form a ternary complex which subsequently experiences redox decomposition, leading to glyceraldehydes and Cr(IV)–PA complex. The uncatalyzed path shows a second-order dependence on [H+], whereas the PA-catalyzed path shows zero-order dependence on [H+]. Both the uncatalyzed and PA-catalyzed path show a first-order dependence on [glycerol]T and [Cr(VI)]T. The PA-catalyzed path is first order in [PA]T. All these observations remain unaltered in the presence of externally added surfactants. The effect of the cationic surfactant cetyl pyridinium chloride (CPC) and anionic surfactant sodium dodecyl sulfate (SDS) on the PA-catalyzed path have been studied. CPC inhibits, whereas SDS accelerates the reaction. Here, SDS is a catalyst for glyceraldehydes production and at the same time ...