Inter- and Intramolecular Redox Reactions of Substituted Phenylperoxyl Radicals in Aqueous Solutions

Substituted phenylperoxyl radicals (XC{sub 6}H{sub 4}OO{sup .}) were produced from 4-bromoanisole, 4-bromophenol, and 4-bromo-N, N-dimethylaniline (XC{sub 6}H{sub 4}Br) in irradiated aqueous alcohol solutions. The process involves reductive debromination of these compounds by reaction with solvated electrons and subsequent reaction of the substituted phenyl radicals (XC{sub 6}H{sub 4}{sup .}) with O{sub 2}. The rate constants for reaction of 4-MeOC{sub 6}H{sub 4}{sup .} with O{sub 2} and with several alcohols and for reactions of 4-MeOC{sub 6}H{sub 4}OO{sup .} with various reductants are determined. The 4-MeOC{sub 6}H{sub 4}OO{sup .} radical decays with a second-order rate law and partially yields the 4-MeOC{sub 6}H{sub 4}O{sup .} radical. On the other hand, 4-HOC{sub 6}H{sub 4}OO{sup .} undergoes an intramolecular electron transfer, through its deprotonated form, {sup -}OC{sub 6}H{sub 4}OO{sup .}, to yield the 4-HOOC{sub 6}H{sub 4} O{sup .} radical. Me{sub 2}NC{sub 6}H{sub 4}OO{sup .} undergoes both intramolecular transformation and radical-radical processes, but its protonated form, Me{sub 2}HN{sup +}C{sub 6}H{sub 4}OO{sup .}, undergoes mainly radical-radical reactions. 20 refs., 3 figs., 1 tab.