Catalytic oxidation of Fe(II) aqua ions with atmospheric oxygen in the presence of Pd(II) tetraaqua complex and an aromatic compound

The effect of a series of aromatic compounds (toluene, benzyl alcohol, benzonitrile, phenylacetonitrile, and o-cyanotoluene) in a concentration of 0.01 M on the oxidation of Fe(II) aqua ions with oxygen in the presence of Pd(II) tetraaqua complex at 25–70°C was revealed. In the presence of an aromatic compound, palladium black is not formed, which results in an increased yield of Fe(III) in the Pd-catalyzed oxidation of Fe(II) with oxygen in a perchloric acid medium. A scheme involving the formation of a complex of palladium species in an intermediate oxidation state with arene and molecular oxygen was suggested.