Reductive transformations of halophenols on illuminated ferrocyanide ions

The reductive decomposition of several halogenated pollutants (2,4,5-trichlorophenol, 2,5 and 3,4-dichlorophenol, 2-and 4-chlorophenol, 4-bromophenol and 4-fluorophenol) was evaluated by adopting illuminated ferrocyanide ions as source for hydrated electrons; in these conditions, the photogenerated solvated electrons interact with substances present in solution so reducing them. The constant rates of halophenols with hydrated electrons achieved with ferrocyanide system show a good correlation with the data estimated by adopting pulse radiolysis, so that it could be adopted as an alternative to the pulse radiolysis in evaluating the reactivity of organic compounds toward hydrated electrons. Furthermore, it permits to pursue the fate of initial molecule through the intermediates identification. As an example, a detailed study about the intermediates produced from 3,4-dichlorophenol and 2,4,5-trichlorophenol is presented and a pattern of reaction pathways accounting for the recognized intermediates is proposed.