ABSTRACT
Biological. A mixed culture of soil bacteria or a Pseudomonas sp. transformed 1,2,3,4tetrachlorobenzene to 2,3,4,5-tetrachlorophenol (Ballschiter and Scholz, 1980). After incubation in sewage sludge for 32 d under anaerobic conditions, 1,2,3,4-tetrachlorobenzene did not biodegrade (Kirk et al., 1989). The half-life of 1,2,3,4-tetrachlorobenzene in an anaerobic enrichment culture was 26.4 h (Beurskens et al., 1993). Potrawfke et al. (1998) reported that a pure culture of Pseudomonas chlororaphis RW71 mineralized 1,2,3,4-tetrachlorobenzene as a sole source of carbon and energy. Intermediate biodegradation products identified were tetrachlorocatechol, tetrachloromuconic acid, 2,3,5-trichlorodienelactone, 2,3,5-trichloro-4-hydroxymuconic acid. In an enrichment culture derived from a contaminated site in Bayou d’Inde, LA, 1,2,4,5tetrachlorobenzene underwent reductive dechlorination yielding 1,2,4-trichlorobenzene. The maximum dechlorination rate, based on the recommended Michaelis-Menten model, was 208 nM/d (Pavlostathis and Prytula, 2000). Photolytic. Irradiation (λ ≥285 nm) of 1,2,3,4-tetrachlorobenzene (1.1-1.2 mM/L) in an acetonitrile-water mixture containing acetone (0.553 mM/L) as a sensitizer gave the following products (% yield): 1,2,3-trichlorobenzene (9.2), 1,2,4-trichlorobenzene (32.6), 1,3-dichlorobenzene (5.2), 1,4-dichlorobenzene (1.5), 2,2′,3,3′,4,4′,5-heptachlorobiphenyl (2.52), 2,2′,3,3′,4,5,6′- heptachlorobiphenyl (1.22), 10 hexachlorobiphenyls (3.50), five pentachlorobiphenyls (0.87), dichlorophenyl cyanide, two trichloroacetophenones, trichlorocyanophenol, (trichlorophenyl)acetonitriles, and 1-(trichlorophenyl)-2-propanone (Choudhry and Hutzinger, 1984). Without acetone, the identified photolysis products (% yield) included 1,2,3-trichlorobenzene (7.8), 1,2,4trichlorobenzene (26.8), 1,2-dichlorobenzene (0.5), 1,3-dichlorobenzene (0.7), 1,4-dichloro-benzene (30.4), 1,2,3,5-tetrachlorobenzene (2.26), 1,2,4,5-tetrachlorobenzene (0.72), 2,2′,3,3′,4,4′,5heptachlorobiphenyl (<0.01), and 2,2′,3,3′,4,5,6′-heptachlorobiphenyl (<0.01) (Choudhry and Hutzinger, 1984). The sunlight irradiation of 1,2,3,4-tetrachlorobenzene (20 g) in a 100-mL borosilicate glass-stoppered Erlenmeyer flask for 56 d yielded 4,280 ppm heptachlorobiphenyl (Uyeta et al., 1976). When an aqueous solution containing 1,2,3,4-tetrachlorobenzene and a nonionic surfactant micelle (Brij 58, a polyoxyethylene cetyl ether) was illuminated by a photoreactor equipped with 253.7-nm monochromatic UV lamps, no photoisomerization was observed. However, based on photodechlorination of other polychlorobenzenes under similar conditions, it was suggested that tri-and dichlorobenzenes, chlorobenzene, benzene, phenol, hydrogen, and chloride ions are likely to form. The half-life for this reaction, based on the first-order photodecomposition rate of 5.24 x 10-3/sec, is 2.2 min (Chu and Jafvert, 1994). Toxicity: EC50 (48-h) for Daphnia magna 280 µg/L (Marchini et al., 1999), Pseudokirchneriella subcapitata 0.76 mg/L (Hsieh et al., 2006). LC50 (chronic 28-d) for Brachydanio rerio 410 µg/L (van Leeuwen et al., 1990). LC50 (14-d) for Poecilia reticulata 803 µg/L (Könemann, 1981). LC50 (96-h) for fathead minnows 1.1 mg/L (Veith et al., 1983), Poecilia reticulata 365 µg/L (van Hoogen and Opperhuizen, 1988). LC50 259 and 345 mg/L (soil porewater concentration) for earthworm (Eisenia andrei) and 237 and 497 mg/L (soil porewater concentration) for earthworm (Lumbricus rubellus) (Van Gestel and Ma, 1993). Acute oral LD50 for rats 1,167 mg/kg (quoted, RTECS, 1985). Uses: Dielectric fluids; organic synthesis.
