1,2-DICHLOROBENZENE

Note: May contain chlorobenzene, trichlorobenzenes, 1,3-dichlorobenzene and 1,4-dichlorobenzene as impurities. CASRN: 95-50-1; DOT: 1591; molecular formula: C6H4Cl2; FW: 147.00; RTECS: CZ4500000; Merck Index: 12, 3106 Physical state, color, and odor: Clear, colorless to pale yellow liquid with a pleasant, aromatic, grassy or vegetable-type odor. At 40 °C, the lowest concentration at which an odor was detected was 200 µg/L. At 25 °C, the lowest concentration at which a taste was detected was 200 µg/L (Young et al., 1996). A detection odor threshold concentration of 4.2 mg/m3 (699 ppbv) was reported by Punter (1983). Melting point (°C): -16 to -14 (Fluka, 1988) -17.00 (Martin et al., 1979) Boiling point (°C): 180.190 (Růžička et al., 1998) Density (g/cm3): 1.3048 at 20 °C (Weast, 1986) 1.30024 at 25 °C (Kirchnerová and Cave, 1976) 1.29920 at 30.00 °C (Sekar and Naidu, 1996) Diffusivity in water (x 10-6 cm2/sec): At 25 °C: 9.4 (x = 2 x 10-7), 8.9 (x = 4 x 10-7), 8.7 (x = 8 x 10-7) (Gabler et al., 1996) Flash point (°C): 66 (NIOSH, 1997) Lower explosive limit (%): 2.2 (NIOSH, 1997) Upper explosive limit (%): 9.2 (NIOSH, 1997) Entropy of fusion (cal/mol⋅K): 12.1 (Yalkowsky and Valvani, 1980)

3.19 (Dean, 1987) Henry’s law constant (x 10-3 atm⋅m3/mol): 1.2 at 20 °C (gas stripping-GC, Oliver, 1985) 2.83 at 37 °C (Sato and Nakajima, 1979) 1.63, 1.43, 1.68, 1.57, and 2.37 at 10, 15, 20, 25, and 30 °C, respectively (EPICS, Ashworth et al.,

1988) 1.39 at 20.00 °C (inert gas stripping, Hovorka and Dohnal, 1997) 1.92 at 25 °C (gas stripping-GC, Shiu and Mackay, 1997) Ionization potential (eV): 9.06 (NIOSH, 1997) Bioconcentration factor, log BCF: 1.95 (bluegill sunfish) (Barrows et al., 1980; Veith et al., 1980) 2.43, 2.75 (Oncorhynchus mykiss, Oliver and Niimi, 1983) 3.94 (Atlantic croakers), 4.46 (blue crabs), 3.79 (spotted sea trout), 3.82 (blue catfish) (Pereira et

al., 1988) 4.17 (green alga, Selenastrum capricornutum) (Casserly et al., 1983) Soil organic carbon/water partition coefficient, log Koc: 2.255 (Willamette silt loam, Chiou et al., 1979) 2.43 (Marlette soil - B+ horizon), 2.45 (Marlette soil - A horizon) (Lee et al., 1989) 2.51 (Woodburn silt loam, Chiou et al., 1983) 2.59 (Appalachee soil, Stauffer and MacIntyre, 1986) 2.69 (peaty soil, Friesel et al., 1984) 2.70 (Piwoni and Banerjee, 1989) 3.10 (Captina silt loam), 2.90 (McLaurin sandy loam) (Walton et al., 1992) 3.02 (Tinker), 2.83 (Carswell), 2.45 (Barksdale), 2.91 (Blytheville), 3.51 (Traverse City), 3.29

(Borden), 2.85 (Lula) (Stauffer et al., 1989) 2.46 (normal soils), 2.70 (suspended bed sediments) (Kile et al., 1995) 3.29-3.49 (glaciofluvial, sandy aquifer, Nielsen et al., 1996) 2.44 (muck), 2.38 (Eustis sand) (Brusseau et al., 1990) 2.96 (decyltrimethylammonium clay), 3.20 (tetradecyltrimethylammonium clay), 3.22 (octadecyl-

trimethylammonium clay) (Deitsch et al., 1998) 3.09 (Calvert silt loam, Xia and Ball, 1999) Octanol/water partition coefficient, log Kow: 3.38 (generator column-GC, Wasik et al., 1981; generator column, Doucette and Andren, 1988) 3.40 (23 °C, shake flask-LSC, Banerjee et al., 1980; 25 °C, shake flask-GC, Watarai et al., 1980) 3.55 at 22 °C (shake flask-GC, Könemann et al., 1979) 3.433 at 25 °C (shake flask-GLC, de Bruijn et al., 1989) 3.34 (estimated from HPLC capacity factors, Hammers et al., 1982) 3.49 (shake flask-GC, Pereira et al., 1988) 3.51, 3.41, 3.29, 3.20, and 3.09 at 5, 15, 25, 35, and 45 °C, respectively (shake flask-GC, Bahadur

et al., 1997) 3.75 (Veith et al., 1980) 3.56 (generator column-HPLC, Garst, 1984) 3.45 at 25 °C (Paschke et al., 1998) 3.70 at 25 °C (dialysis-HPLC, Andersson and Schräder, 1999)

Miscible with alcohol, ether, benzene (Windholz et al., 1983), and many other organic solvents, particularly chlorinated compounds (e.g., carbon tetrachloride, methylene chloride, chloroform, 1,1,1-trichloroethane). Solubility in water: 109 mg/L at 25 °C (shake flask-GC, Boyd et al., 1998) 152.9 mg/L at 25 °C (shake flask-GC, Tam et al., 1996) 137 mg/L at 25 °C (shake flask-HPLC, Banerjee, 1984) 156 mg/L at 25 °C (shake flask-LSC, Banerjee et al., 1980) 148 mg/L at 20 °C (Chiou et al., 1979) 92.7 mg/L at 25 °C (shake flask-UV spectrophotometry, Yalkowsky et al., 1979) 0.628 mM at 25 °C (generator column-GC, Miller et al., 1984) 145 mg/L at 25 °C (Etzweiler et al., 1995) 142.3 mg/L at 30 °C (vapor equilibrium-GC, McNally and Grob, 1984) 149.4 mg/L at 30 °C (vapor equilibrium-GC, McNally and Grob, 1983) 0.017 wt % at 25 °C (shake flask-radiometry, Lo et al., 1986) 97 mg/L at 25 °C (generator column-GC, Paschke et al., 1998) In wt %: 0.005 at 0 °C, 0.0031 at 19.5 °C, 0.0017 at 40.0 °C, 0.0024 at 50.0 °C, 0.0054 at 60.5 °C,

0.0055 at 70.7 °C, 0.0091 at 80.0 °C, 0.0083 at 90.5 °C (shake flask-GC, Stephenson, 1992) 0.0162 and 0.0126 wt % at 10.0 and 20.0 °C, respectively (Schwarz and Miller, 1980) In mg/L: 134 at 20 °C, 145 at 25 °C, 171 at 30 °C, 183 at 35 °C, 194 at 40 °C, 203 at 45 °C, 223 at

55 °C, 232 at 60 °C (Klemenc and Löw, 1930) In mg/L: 127 at 5.0 °C, 132 at 15.0 °C, 149 at 25.0 °C, 162 at 35.0 °C, 204 at 45.0 °C (shake

flask-GC, Ma et al., 2001) In mg/L: 94.4 at 25 °C, 108.0 at 35 °C, 122.7 at 45 °C, 139.1 at 55.0 °C (generator column-GC,

Oleszek-Kudlak et al., 2004a) In mg/kg: 188 at 10 °C, 182 at 20 °C, 178 at 30 °C (shake flask-UV spectrophotometry, Howe et al., 1987) Vapor density: 6.01 g/L at 25 °C, 5.07 (air = 1) Vapor pressure (mmHg): 1.03 at 20 °C (Stull, 1984) 1.9 at 30 °C (quoted, Verschueren, 1983) 62 at 100 °C (quoted, Bailey and White, 1965) 1.5 at 25 °C (quoted, Mackay et al., 1982) Environmental fate: Biological. Pseudomonas sp. isolated from sewage samples produced 3,4-dichloro-cis-1,2dihydroxycyclohexa-3,5-diene. Subsequent degradation of this metabolite yielded 3,4dichlorocatechol, which underwent ring cleavage to form 2,3-dichloro-cis,cis-muconate, followed by hydrolysis to form 5-chloromaleylacetic acid (Haigler et al., 1988). When 1,2-dichlorobenzene was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum, significant biodegradation with gradual acclimation was followed by a deadaptive process in subsequent subcultures. At a concentration of 5 mg/L, 45, 66, 48, and 29% losses were observed after 7, 14, 21, and 28-d incubation periods, respectively. At a concentration of 10 mg/L, only 20, 59, 32, and 18% losses were observed after 7, 14, 21, and 28-d incubation periods, respectively (Tabak et al., 1981). Groundwater. Nielsen et al. (1996) studied the degradation of 1,2-dichlorobenzene in a shallow,

study, a cylinder that was open at the bottom and screened at the top was installed through a cased borehole approximately 5 m below grade. Five liters of water was aerated with atmospheric air to ensure aerobic conditions were maintained. Groundwater was analyzed weekly for approximately 3 months to determine 1,2-dichlorobenzene concentrations with time. The experimentally determined first-order biodegradation rate constant and corresponding half-life following a 13-d lag phase were 0.06/d and 11.55 d, respectively. Photolytic. Titanium dioxide suspended in an aqueous solution and irradiated with UV light (λ = 365 nm) converted 1,2-dichlorobenzene to carbon dioxide at a significant rate (Matthews, 1986). The sunlight irradiation of 1,2-dichlorobenzene (20 g) in a 100-mL borosilicate glass-stoppered Erlenmeyer flask for 56 d yielded 2,270 ppm 2,3′,4′-trichlorobiphenyl (Uyeta et al., 1976). When an aqueous solution containing 1,2-dichlorobenzene (190 µM) and a nonionic surfactant micelle (Brij 58, a polyoxyethylene cetyl ether) was illuminated by a photoreactor equipped with 253.7-nm monochromatic UV lamps, photoisomerization took place yielding 1,3-and 1,4dichlorobenzene as the principal products. The half-life for this reaction, based on the first-order photodecomposition rate of 1.35 x 10-3/sec, is 8.6 min (Chu and Jafvert, 1994). Chemical/Physical. Anticipated products from the reaction of 1,2-dichlorobenzene with ozone or OH radicals in the atmosphere are chlorinated phenols, ring cleavage products, and nitro compounds (Cupitt, 1980). Based on an assumed base-mediated 1% disappearance after 16 d at 85 °C and pH 9.70 (pH 11.26 at 25 °C), the hydrolysis half-life was estimated to be >900 yr (Ellington et al., 1988). When 1,2-dichlorobenzene in hydrogen-saturated deionized water was exposed to a slurry of palladium catalyst (1%) at room temperature, benzene formed via the intermediate chlorobenzene. The reaction rate decreased in the order of MCM-41 (mesoporous oxide having a silicon: aluminum ratio of 35) > alumina > Y (dealuminated zeolite having a silicon:aluminum ratio of 15). It appeared the reaction rate was directly proportional to the surface area of the support catalyst used (Schüth and Reinhard, 1997). At influent concentrations of 1.0, 0.1, 0.01, and 0.001 mg/L, the GAC adsorption capacities at pH 5.5 were 129, 47, 17, and 64 mg/g, respectively (Dobbs and Cohen, 1980). Exposure limits: NIOSH REL: ceiling 50 ppm (300 mg/m3), IDLH 200 ppm; OSHA PEL: ceiling 50 ppm; ACGIH TLV: TWA 25 ppm, ceiling 50 ppm (adopted). Symptoms of exposure: Lacrimation, depression of central nervous system, anesthesia, and liver damage (Patnaik, 1992). An irritation concentration of 150.00 mg/m3 in air was reported by Ruth (1986). Toxicity: Concentrations that reduce the fertility of Daphnia magna in 2 wk for 50% (EC50) and 16% (EC16) of the population are 0.55 and 0.37 mg/L, respectively (Calamari et al., 1983). EC50 (96-h) and EC50 (3-h) concentrations that inhibit the growth of 50% of Selenastrum capricornutum population are 2.2 and 10.0 mg/L, respectively (Calamari et al., 1983). EC50 (48-h) for Daphnia magna 1.15 mg/L (Marchini et al., 1999), Pseudokirchneriella subcapitata 3.28 mg/L (Hsieh et al., 2006). IC50 (24-h) for Daphnia magna 0.78 mg/L (Calamari et al., 1983). LC50 (contact) for earthworm (Eisenia fetida) 21 µg/cm2 (Neuhauser et al., 1985). LC50 (14-d) for Poecilia reticulata 5.85 mg/L (Könemann, 1981). LC50 (96-h) for bluegill sunfish 5.6 mg/L (Spehar et al., 1982), fathead minnows 57 mg/L, grass shrimp 9.4 mg/L (Curtis et al., 1979), Cyprinodon variegatus 9.7 ppm using natural seawater (Heitmuller et al., 1981). LC50 (72-h) for Cyprinodon variegatus 9.7 ppm (Heitmuller et al., 1981).