4-Hydroxy 4/-chlorobiphenyl

Bergman et al. 1994). All major -ortho-VCBs are transformed to 4-hydroxy-chlorobiphenyl metabolites, retained in plasma or blood. Changes in residue patterns, including actual increases over time, indicating possible dechlorination products were observed by Wolff et al. (1992). Brown (1994) further suggested that humans were capable of very slow PCB dechlorination. 

For polychlorinated biphenyls (PCBs), rate constants were highly dependent on the number of chlorine atoms, and calculated atmospheric lifetimes varied from 2 d for 3-chlorobiphenyl to 34 d for 236-25 pentachlorobiphenyl (Anderson and Hites 1996). It was estimated that loss by hydroxy-lation in the atmosphere was a primary process for the removal of PCBs from the environment. It was later shown that the products were chlorinated benzoic acids produced by initial reaction with a hydroxyl radical at the 1-position followed by transannular dioxygenation at the 2- and 5-positions followed by ring fission (Brubaker and Hites 1998). Reactions of hydroxyl radicals with polychlorinated dibenzo[l,4]dioxins and dibenzofurans also play an important role for their removal from the atmosphere (Brubaker and Hites 1997). The gas phase and the particulate phase are in equilibrium, and the results show that gas-phase reactions with hydroxyl radicals are important for the... 

A rearrangement (NIH shift) occurred during the transformation of 2-chlorobiphenyl to 2-hydroxy-3-chlorobiphenyl by a methanotroph, and is consistent with the formation of an intermediate arene oxide (Adriaens 1994). The occurrence of such intermediates also offers plausible mechanisms for the formation of nitro-containing metabolites that have been observed in the degradation of 4-chlo-robiphenyl in the presence of nitrate (Sylvestre et al. 1982). 

Recently, the PCB-biodegradative capabilities of methanotrophs have been demonstrated (Adriaens, 1994). In this study, 2-CB was oxidized by a methanotrophic culture (CSC1) to a hydroxylated chlorobiphenyl intermediate identified as 2-hydroxy-3-chlorobiphenyl. This intermediate indicated that the metabolite was formed via a concerted oxidation involving an arene oxide which rearranges spontaneously via an NIH shift. No studies have shown, however, that methanotrophs can degrade more highly chlorinated PCBs, and their utility for bioremediation processes does not seem promising. 

AI3-03271 2-Biphenyloi, 3-chloro- Caswell No. 211 2-Ch oro-6-phenylphenol 2-Hydroxy-3-chlorobiphenyl 2-Phenyl-6-ohlorophenol 3-Chloro-(1,1 -biptienyl)-2-ol 3-Chloro-2-biphenylol 3-Chlorobiphenyl-iol 6-Chloro-2-phenylphenol Dowoide 31 Dowdde 32 EPA Pesticide Chemical Code 062210 NSC 2500, Used as an antiseptic and fungicide. Registered by EPA as an antimicrobial and disinfectant (cancelled). Yellow, viscous liquid mp = 6 bp = 317 318" (dec) 1,24 insoluble in H2O, soluble in alkali and in most organic solvents. Dow Chem. U.S.A. 

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