Ruthenium-catalyzed dehalogenation of halogenated compounds

Water-soluble ruthenium(II) complexes are effective catalysts for the deep oxidation of chlorinated organics in the presence of hydrogen peroxide or mono-persulfate at room temperature. Reactions are conducted either in nitromethane–water two phase or in water– acetonitrile mixtures or in water alone, in the presence of a surfactant agent (if the case) with the ruthenium(II) catalysts [Ru(H2O)2(dmso)4](BF4)4, [RuCl2(dmso)4] or [RuPcS] (dmso_ dimethylsulfoxide; PcS_tetra-sulfo-phthalocyaninate). The oxidation of various chlorinated organics (chloro, bromo-, iodo- and nitro-benzene, polychlorobenzenes, polychlorophenols) was followed by monitoring the nature and the relative amounts of the final products: chlorinated substrates are often converted into hydrochloric acid and carbon dioxide. Factors such as solvent and oxidant affect the reactions, the most favorable conditions being achieved in aqueous media. Substituted benzenes are oxidized via an initial electrophilic attack followed by a series of faster steps, whereas with polychlorophenols, which are more sensitive to oxidation than substituted benzenes, the reaction is also radical in character.