Mild and Efficient Oxidation of Alcohols with NaIO4 Catalyzed by a Manganese Porphyrin-polyoxometalate Hybrid Material

Efficient and selective oxidation of alcohols with NaIO4 catalyzed by an organic-inorganic hybrid material in which manganese(III)5,10,15,20-tetrakis(4-aminophenyl)porphyrin chloride, MnIII(TAPP)Cl, is covalently linked to a Lindqvist structure of polyoxometalate, Mo6O192-, at room temperature is reported. The effect of various parameters such as catalyst amount, solvent and oxidant were studied. The catalyst, MnP-POM, showed high activity not only in the oxidation of benzylic and linear alcohols but also in the oxidation of secondary alcohols and their corresponding ketones were obtained in good yields. A good selectivity observed in the case of cinnamyl alcohol and the only alcoholic group is oxidized and no epoxide was obtained. The MnP-POM catalyst is stable under the reaction conditions and While, the homogeneous MnIII(TAPP)Cl cannot recover even one time, the hybrid catalyst can be filtered and reused several times without significant loss of its initial activity. Covalent linkage of the MnIII(TAPP)Cl to the POM provide way of stabilizing the metalloporphyrin against deactivation during the catalytic cycles