Chlorobiphenyls

Mizutani and coworkers57a confirmed the presence of polychloro(methylsulfonyl)biphenyls (159-170) as sulfur-containing metabolites of chlorobiphenyls (Cl-BP) in the feces of mice based on both GLC-mass spectrometry and chemical derivatization. In some cases comparison with authentic samples (161 and 162) was also made. When preparing 161 and 162,2,5-dichloro-3-(methylsulfonyl)aniline, 2,5-dichloro-l-iodo-3-(methylsulfonyl)benzene and 2,2, 5,5 -tetrachloro-3,3 -bis(methyl-sulfonyl)biphenyl were also obtained and their four peak El mass spectra reported572. Similar data were given for the corresponding 4-substituted intermediates, which were involved in the preparation of 162. Also 2,4, 5-trichloro-2 -(methylsulfonyl)-biphenyl was prepared and its four peak mass spectra given. Metabolites 163 and 164 were also identified by comparison with the authentic standards. 

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... 

The degradation of 4-chlorobiphenyl by Sphingomonas paucimobilis strain BPSl-3 formed the intermediates 4-chlorobenzoate and 4-chlorocatechol. Fission products from the catechol reacted with NH4+ to produce chloropyridine carboxylates (Davison et al. 1996) (Figure 2.2c). 

Adriaens P (1994) Evidence for chlorine migration dnring oxidation of 2-chlorobiphenyl by a type 11 metha-notroph. Appl Environ Microbiol 60 1658-1662. 

Hurtubise Y, D Barriault, M Sylvestre (1998) Involvement of the terminal oxygenase P subunit in the biphenyl dioxygenase reactivity pattern towards chlorobiphenyls. J Bacterial 180 5828-5835. 

Blasco R, M Mallavarapu, R-M Wittich, KN Timmis, DH Pieper (1997) Evidence that formation of protoanemonin from metabolites of 4-chlorobiphenyl degradation negatively affects the survival of 4-chlorobiphenyl-cometabolizing microorganisms. Appl Environ Microbiol 63 434. 

Shields MS, SW Hooper, GS Sayler (1985) Plasmid-mediated mineralization of 4-chlorobiphenyl. J Bacterial 163 882-889. 

Sondossi M, M Sylvestre, D Ahmad (1992) Effects of chlorobenzoate transformation on the Pseudomonas testosteroni biphenyl and chlorobiphenyl degradation pathway. Appl Environ Microbiol 58 485-495. 

Sylvestre M (1980) Isolation method for bacterial isolates capable of growth on p-chlorobiphenyl. Appl Environ Microbiol 39 1223-1224. 

FIGURE 9.6 Aerobic degradation of (a) biphenyl by biphenyl-2,3-dioxygenase, (b) a polychlorinated 4 -chlorobiphenyl. 

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). 

Ahmad D, R Masse, M Sylvestre (1990) Cloning, physical mapping and expression in Pseudomonas putida of 4-chlorobiphenyl transformation genes from Pseudomonas testosteroni strain B-356 and their homology to the genomic DNA from other PCB-degrading bacteria. Gene 86 53-61. 

Chavez EP, H Liinsdorf, CA Jerez (2004) Growth of polychlorinated-biphenyl-degrading bacteria in the presence of biphenyl and chlorobiphenyls generates oxidative stress and massive accumulation of inorganic polyphosphate. Appl Environ Microbiol 70 3064-3072. 

Furukawa K, T Miyazaki (1986) Cloning of a gene cluster encoding biphenyl and chlorobiphenyl degradation in Pseudomonas pseudoalcaligenes. J Bacterial 166 392-398. 

Sylvestre M (1995) Biphenyl/chlorobiphenyls catabolic pathway of Comamonas testosteroni B-356 prospect for use in bioremediation. Int Biodet Biodeg 35 189-211. 

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