INVESTIGATIONS OF REACTIONS OF SELECTED AZAARENES WITH RADICALS IN WATER - 2 - CHLORINE AND BROMINE RADICALS

The halogen radicals that react with azaarenes are produced by the pho tooxidation of halogenide anions with hydroxyl and sulfate radicals an d exist as complexes of the radical and the respective halogenide anio n in the aqueous phase. The main reaction products of the reactions ar e identified, and in the case of the bromine radicals, the second orde r rate constants are determined. Oxidation takes place according to th e different redox potentials of the two reactants and is especially ob served for chlorine radicals. A typical product spectrum comparable wi th that in reactions with hydroxyl and sulfate radicals has been found . The formation of some oxidation products in reactions of bromine rad icals is in contradistinction to the oxidation potentials of the azaar enes and can be understood only by the reaction of their excited state s. The halogenation is the main reaction of the azaarenes. Halogenatio n products of both, the benzene and the pyridine/diazine rings, have b een found. The halogenation of the pyridine/diazine ring again require s the reaction of excited states. The majority of derivatives is halog enated in substitution reactions, but in the reaction of benzo[h]quino line, addition is also observed. The resonance energy per electron is responsible for the change in the halogenation mechanism from substitu tion to addition.