Inter- and intramolecular redox reactions of substituted phenylperoxyl radicals in aqueous solutions

Substituted phenylperoxyl radicals (XC₆H₄OO^·)were produced from 4-bromoanisole, 4-bromophenol, and 4-bromo-N, N-dimethylaniline (XC₆H₄Br) 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 (XC₆H₄^·) with O₂. The rate constants for reaction of 4-MeOC₆H₄^· with O₂ and with several alcohols and for reactions of 4-MeOC₆H₄OO^· with various reductants are determined. The 4-MeOC₆H₄OO^· radical decays with a second-order rate law and partially yields the 4-MeOC₆H₄O^· radical. On the other hand, 4-HOC₆H₄OO^· undergoes an intramolecular electron transfer, through its deprotonated form, ^-OC₆H₄OO^·, to yield the 4-HOOC₆H₄ O^· radical. Me₂NC₆H₄OO^· undergoes both intramolecular transformation and radical-radical processes, but its protonated form, Me₂HN⁺C₆H₄OO^·, undergoes mainly radical-radical reactions.