Effects of pH and organic co-solvents on the oxidation of naphthalene with peroxosulfate catalyzed by iron(III) tetrakis(p-sulfonatophenyl)porphyrin

Abstract

The oxidation of naphthalene was investigated in a biomimetic catalytic system using KHSO 5 and iron(III) tetrakis(p-sulfonatophenyl)porphyrin ( FeTPPS ) in order to elucidate the influence of solution forms, such as buffer pH and co-solvent types, on the reaction. 1,4-naphthoquinone was the main byproduct and the efficiency of oxidation, particularly 1,4-naphthoquinone formation, was influenced by pH and the type of co-solvent used. The most efficient conversion of 1,4-naphthoquinone was observed at an acidic pH (= 3). At higher pH , the formation of μ-oxo species ( OFe 2( TPPS )2) leads to a decrease of the percentage of naphthalene oxidized. In addition, the organic co-solvents (methanol, ethanol, 2-propanol and acetonitrile) influenced the amounts of naphthalene conversion. The amounts of 1,4-naphthoquinone formed were related to the electron donating character of the organic co-solvents.