OXIDATION OF 2,6-DI-TERT-BUTYLPHENOL BY MOLECULAR-OXYGEN CATALYZED BY TETRASODIUM PHTHALOCYANINATOCOBALT(II)TETRASULFONATE BOUND TO A POLYMER COLLOID

Crosslinked cationic latexes based on polystyrene, poly[styrene-co-(methyl methacrylate)] and poly(methyl methacrylate) were prepared by an emulsion polymerization process using 2 mol-% of a quaternary ammonium surfactant monomer. Phthalocyaninatocobalt(II)tetrasulfonate (CoPcTs) bound to these latexes were found to enhance the rate of autoxidation of 2,6-ditert-butylphenol in water. All CoPcTs-latex catalysts were more active than the water soluble CoPcTsNa4. The styrene latex bound with CoPcTs was the most active catalyst. The reaction products were identified as the oxidative coupling products 3,3',5,55'-tetra-tert-butyl-4,4'-dioxo-1,1'-bicyclohexadienylidene (DPQ) and 2,6-di-tert-butyl-1,4-benzoquinone (BQ). The ratio DPQ/BQ was found to be affected by the nature of microenvironment. The rate of autoxidation catalyzed by CoPcTs bound to the styrene latex was found to be zero order with respect to the phenol concentration. The reaction rates increase with pH in the range 7-9. The rate of autoxidation increases with increasing concentration of CoPcTs from 1,0.10(-6) to 2,5.10(-5) mol/L and then it levels off. At constant concentration of CoPcTs in the reaction mixture, the rate as a function of the weight of latex shows a maximum. The rate shows a linear dependence on partial pressure of dioxygen. Recycling of the latex catalyst results in a reduced activity after successive runs.