Micellar Catalysis on 1,10-Phenanthroline Promoted Chromic Acid Oxidation of Dimethyl Sulfoxide to Dimethyl Sulfone in Aqueous Media at Room Temperature

Abstract

The monomeric species of Cr(VI) was found to be kinetically active in the absence of 1,10-phenanthroline (phen) under pseudo-first order conditions, whereas in the 1,10-phenanthroline promoted path, the Cr(VI)-phenanthroline complex undergoes a nucleophilic attack by dimethyl sulfoxide (DMSO) to form a ternary complex which subsequently undergoes a redox decomposition leading to dimethyl sulfone and Cr(III)-phenanthroline complex. A detailed study was done to investigate the effect of cationic surfactant N-cetylpyridinium chloride (CPC), anionic surfactant sodium dodecyl sulphate (SDS) and neutral surfactant (TX-100) on the phen promoted chromic acid oxidation of DMSO in aqueous media at 30°C. The aggregation and morphology of the micelles formed by the surfactants were studied by optical microscope and Transmission Electron Microscope (TEM). 1,10-phenanthroline in association with SDS micelle exhibited almost 70-fold rate enhancements compared to the uncatalyzed reaction path.