Directing Effects of Phenyl Substitution in the Reaction of OH Radical with Aromatics: The Radiolytic Hydroxylation of Biphenyl

Article abstract of DOI:10.1021/j100104a025

The initial yields for formation of 2-, 3-, and 4-hydroxybiphenyl following the radiolytic oxidation of biphenyl in the presence of ferricyanide are respectively, 1.19, 1.13, and 1.55 molecules/100 eV.These yields reflect relative rates of 0.71:0.37:1 for *OH radical attack on each of the ortho, meta, and para positions of biphenyl.Comparison of the corresponiding partial rate constants to that of benzene shows that the phenyl substitution has a significant effect in directing *OH addition to the ortho and para positions of aromatic systems.Comparison with phenol shows that a phenyl substituent has only a slightly smaller effect than does OH in increasing the partial rate constant at the ortho and para positions but is substantially less effective in decreasing the rate of *OH reaction at the meta position.