Aromatic Oxidation with Peroxydiphosphate Catalyzed by Metal Ions

Article abstract of DOI:10.1021/jo00323a025

Aqueous potassium peroxydiphosphate brings about aromatic ring hydroxylation of benzene and toluene in modest yields in the presence of suitable metal ion oxidants, notably cupric ion.The acidity function (-H_O) of the reaction solution for the optimum conditions is -1.5-0, i.e., 0.05-1 M H(+), on the basis of a plot of total product yield vs. -H_O.The selectivity of ring hydroxylation increases with decreasing acidity of the aqueous solution and with increasing concentration of Cu(2+).But the reverse is true for the total product yield under these conditions.Our observations are consistent with a scheme by which the radical H2PO4 oxidizes the aromatic to a radical cation, similar to the mechanism suggested for aromatic hydroxylation by sulfate radical SO4(-).