Photochemical behaviour of 1,4-dichlorobenzene in aqueous solution

Several photoproducts were identified in the direct photolysis of 1,4-dichl orobenzene (1,4-DCB) in air-saturated aqueous solution, namely 4-chlorophen ol, hydroquinone, hydroxybenzoquinone, and 2,5-dichlorophenol. In the absen ce of oxygen the latter is not formed and phenol was detected, but the unex pected formations of 4,4'-dichlorobiphenyl, 2,4,5-trichlorobiphenyl, and a terphenyl derivative are observed. Mechanisms are proposed to explain the f ormations of identified photoproducts. The phototransformation of 1,4-DCB m ay be photoinduced by NO3- or Fe-III salts. The main primary product is 2,5 -dichlorophenol, which results from a hydroxylation without dechlorination. Some other products have been identified in particular 4-chlorophenol and 2,5-dichlorobenzoquinone in the case of Fe-III salts.