1,4-DICHLOROBENZENE

Cl Note: May contain chlorobenzene, trichlorobenzenes, 1,2-dichlorobenzene and 1,3-dichlorobenzene as impurities. CASRN: 106-46-7; DOT: 1592; molecular formula: C6H4Cl2; FW: 147.00; RTECS: CZ4550000; Merck Index: 12, 3107 Physical state, color, and odor: Colorless to white crystals with a penetrating, sweet, mothball or almond-like odor. At 40 °C, the average odor threshold concentration and the lowest concentration at which an odor was detected were 18 and 4.5 µg/L, respectively. Similarly, at 25 °C, the average taste threshold concentration and the lowest concentration at which a taste was detected were 32 and 11 µg/L, respectively (Young et al., 1996). A detection odor threshold concentration of 73 µg/m3 (121 ppbv) was reported by Punter (1983). Melting point (°C): 52.7 (Plato and Glasgow, 1969) 53.10 (Martin et al., 1979) Boiling point (°C): 173.864 (Růžička et al., 1998) Density (g/cm3): 1.2475 at 20 °C (Weast, 1986) Diffusivity in water (x 10-6 cm2/sec): At 25 °C: 9.9 (x = 2 x 10-7), 9.3 (x = 4 x 10-7) (Gabler et al., 1996) Flash point (°C): 65.6 (NIOSH, 1997) Lower explosive limit (%): 2.5 (NIOSH, 1997) Entropy of fusion (cal/mol⋅K): 12.6 (Plato and Glasgow, 1969) 13.3 (Ueberreiter and Orthman, 1950) 13.4 (Yalkowsky and Valvani, 1980) 13.12 (van der Linde et al., 2005)

4.100 (DSC, Plato and Glasgow, 1969) 4.34 (Wauchope and Getzen, 1972) 4.54 (Miller et al., 1984) 4.28 (van der Linde et al., 2005) Henry’s law constant (x 10-3 atm⋅m3/mol): 3.1 (Pankow and Rosen, 1988) 2.72 at 25 °C (gas stripping-UV spectrophotometry, Warner et al., 1987) 1.5 at 20 °C (gas stripping-GC, Oliver, 1985) 2.12, 2.17, 2.59, 3.17, and 3.89 at 10, 15, 20, 25, and 30 °C, respectively (EPICS, Ashworth et al.,

1988) 1.86 at 20.00 °C (inert gas stripping, Hovorka and Dohnal, 1997) 2.41 at 25 °C (gas stripping-GC, Shiu and Mackay, 1997) 1.88 at 25 °C (continuous flow sparger, Sproule et al., 1991) Ionization potential (eV): 8.95 (quoted, Horvath, 1982) Bioconcentration factor, log BCF: 2.71, 2.86, 2.95 (rainbow trout, Oliver and Niimi, 1985) 2.00, 1.70, and 2.75 for algae, fish, and activated sludge, respectively (Freitag et al., 1985) 1.78 (bluegill sunfish, Veith et al., 1980) 2.33 determined for rainbow trout during a 4-d exposure under static test conditions (Neely et al.,

1974) 3.91 (Atlantic croakers), 4.53 (blue crabs), 4.09 (spotted sea trout), 3.51 (blue catfish) (Pereira et

al., 1988) 2.47 (Jordanella floridae, Devillers et al., 1996) 2.04 (fathead minnow, Carlson and Kosian, 1987) 3.26 (Poecilia reticulata, Könemann and van Leeuwen, 1980) 1.89 (wet weight based) and -0.60 (lipid based) for Gambusia affinis (Chaisuksant et al., 1997) 2.90, 3.36, 3.43, 3.60, 3.73, and 3.79 for olive, holly, grass, ivy, mock orange, and pine leaves,

respectively (Hiatt, 1998) Soil organic carbon/water partition coefficient, log Koc: 2.44 (Woodburn silt loam, Chiou et al., 1983) 2.48 (Garyling soil), 2.85 (average using five soils) (Hutzler et al., 1983) 2.60 (Lincoln sand, Wilson et al., 1981) 2.63 (Friesel et al., 1984) 2.78, 2.87, 3.14 (Schwarzenbach and Westall, 1981) 2.92 (humic acid polymers, Chin and Weber, 1989) 2.96 (Eerd soil, Loch et al., 1986) 2.82 (Apison soil), 2.93 (Fullerton soil), 2.45 (Dormont soil) (Southworth and Keller, 1986) 3.29, 3.38, 3.53 (glaciofluvial, sandy aquifer, Nielsen et al., 1996) 3.27 (Lake Oostvaarders plassen sediment, Ter Laak et al., 2005) 2.57 (sandy soil, Van Gestel and Ma, 1993) Average Kd values for sorption of 1,4-dichlorobenzene to corundum (α-Al2O3) and hematite

(α-Fe2O3) were 0.00451 and 0.0105 mL/g, respectively (Mader et al., 1997) Octanol/water partition coefficient, log Kow: 3.35 at 25 °C (modified shake-flask-UV spectrophotometry, Sanemasa et al., 1994)

generator column-HPLC/GC, Wasik et al., 1981)

3.38 (Chiou et al., 1977; generator column-HPLC/GC, Wasik et al., 1981; Miller et al., 1984) 3.62 at 22 °C (shake flask-GC, Könemann et al., 1979) 3.444 at 25 °C (shake flask-GLC, de Bruijn et al., 1989; shake flask-HPLC, Brooke et al., 1990) 3.355 at 25 °C (shake flask-HPLC, Brooke et al., 1990) 3.40 (Campbell and Luthy, 1985) 3.47 (shake flask-GC, Pereira et al., 1988) 3.42, 3.35, 3.23, 3.12, and 3.03 at 5, 15, 25, 35, and 45 °C, respectively (shake flask-GC, Bahadur

et al., 1997) Solubility in organics: Soluble in ethanol, acetone, ether, benzene, carbon tetrachloride, ligroin (U.S. EPA, 1985), carbon disulfide, and chloroform (Windholz et al., 1983) Solubility in water: 42 mg/L at 25 °C (shake flask-GC, Boyd et al., 1998) 65.3 mg/L at 25 °C (shake flask-HPLC, Banerjee, 1984) 74 mg/L at 25 °C (shake flask-LSC, Banerjee et al., 1980) 77 mg/kg at 30 °C (shake flask-interferometer, Gross and Saylor, 1931) 76 mg/L solution at 25 °C (shake flask-UV spectrophotometry, Andrews and Keefer, 1950) 87.15 mg/L at 25 °C (shake flask-GC, Aquan-Yuen et al., 1979) 80 mg/L at 25 °C (Gunther et al., 1968) 90.6 mg/L at 25 °C (shake flask-UV spectrophotometry, Yalkowsky et al., 1979) 0.21 mM at 25 °C (generator column-GC, Miller et al., 1984) 94.4 mg/L at 30 °C (vapor equilibrium-GC, McNally and Grob, 1984) 92.13 mg/L at 30 °C (vapor equilibrium-GC, McNally and Grob, 1983) In mg/kg: 77.8 at 22.2 °C, 83.4 at 24.6 °C, 86.9 at 25.5 °C, 92.6 at 30.0 °C, 102 at 34.5 °C, 121 at

38.4 °C, 159 at 47.5 °C, 173 at 50.1 °C, 210 at 59.2 °C, 218 at 60.7 °C, 230 at 65.1 °C, 237 at 65.2 °C, 281 at 73.4 °C (shake flask-UV spectrophotometry, Wauchope and Getzen, 1972)

In mg/kg: 98 at 10 °C, 89 at 20 °C, 81 at 30 °C (shake flask-UV spectrophotometry, Howe et al., 1987) 581.6 µmol/kg at 25.0 °C (shake flask-UV spectrophotometry, Vesala, 1974) 48.6, 63.0, 81.4, 104.5, and 130 mg/L at 5, 15, 25, 35, and 45 °C, respectively (generator column-

GC, Shiu et al., 1997) 156 and 163 mg/L at 55 and 65 °C, respectively (Klemenc and Löw, 1930) As mole fraction: 1.51 x 10-5 at 20 °C (shake flask-RPLC, Hafkenscheid and Tomlinson, 1981) Vapor pressure (mmHg at 25 °C): 0.4 (quoted, Standen, 1964) 0.7 (quoted, Mackay et al., 1982) Environmental fate: Biological. In activated sludge, <0.1% degraded (mineralized) to carbon dioxide after 5 d (Freitag et al., 1985). When 1,4-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, 55, 61, 34, and 16% losses were observed after 7, 14, 21, and 28-d incubation periods, respectively. At a concentration of 10 mg/L, only 37, 54, 29, and 0% losses were observed after 7, 14, 21, and 28-d incubation periods, respectively (Tabak et al., 1981). Spiess et al. (1995) isolated Xanthobacter flavus from sludge from the river Mulde near

energy. Degradation products identified using GC/MS were 3,6-dichloro-cis-1,2-dihydroxycyclohexa-3,5-diene, 3,6-dichlorocatechol, 3,5-dichloromuconic acid, 2-chloromaleylacetic acid, and 2-chloroacetoacrylic acid. Surface Water. Estimated half-lives of 1,4-dichlorobenzene (1.5 µg/L) from an experimental marine mesocosm during the spring (8-16 °C), summer (20-22 °C), and winter (3-7 °C) were 18, 10, and 13 d, respectively (Wakeham et al., 1983). Groundwater. Nielsen et al. (1996) studied the degradation of 1,4-dichlorobenzene in a shallow, glaciofluvial, unconfined sandy aquifer in Jutland, Denmark. As part of the in situ microcosm 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 1,4-dichlorobenzene concentrations with time. The experimentally determined first-order biodegradation rate constant and corresponding half-life following a 22-d lag phase were 0.05/d and 13.86 d, respectively. Under anaerobic conditions, 1,4-dichlorobenzene in a plume of contaminated groundwater was found to be very persistent (Barber, 1988). Photolytic. Under artificial sunlight, river water containing 2 to 5 ppm of 1,4-dichlorobenzene photodegraded to chlorophenol and phenol (Mansour et al., 1989). A carbon dioxide yield of 5.1% was achieved when 1,4-dichlorobenzene adsorbed on silica gel was irradiated with light (λ >290 nm) for 17 h (Freitag et al., 1985). Irradiation of 1,4-dichlorophenol in air containing nitrogen oxides gave 2,5-dichlorophenol (major product), 2,5-dichloronitrobenzene, 2,5-dichlorophenol, and 2,5-dichloro-4-nitrophenol (Nojima and Kanno, 1980). The sunlight irradiation of 1,4dichlorobenzene (20 g) in a 100-mL borosilicate glass-stoppered Erlenmeyer flask for 56 d yielded 1,860 ppm 2′,4,5′-trichlorobiphenyl (Uyeta et al., 1976). When an aqueous solution containing 1,4-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 1,2-and 1,3dichlorobenzene as the principal products. The half-life for this reaction, based on the first-order photodecomposition rate of 1.34 x 10-3/sec, is 8.6 min (Chu and Jafvert, 1994). A room temperature rate constant of 3.2 x 10-13 cm3/molecule⋅sec was reported for the vapor-phase reaction of 1,4-dichlorobenzene with OH radicals (Atkinson, 1985). Chemical/Physical. Anticipated products from the reaction of 1,4-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 more than 900 yr (Ellington et al., 1988). At influent concentrations of 1.0, 0.1, 0.01, and 0.001 mg/L, GAC adsorption capacities at pH 5.1 were 121, 41, 14, and 4.6 mg/g, respectively (Dobbs and Cohen, 1980). Exposure limits: Potential occupational carcinogen. NIOSH REL: IDLH 150 ppm; OSHA PEL: TWA 75 ppm (450 mg/m3); ACGIH TLV: TWA 10 ppm (adopted). Symptoms of exposure: Repeated inhalation of high concentrations of vapors may cause headache, weakness, dizziness, nausea, vomiting, diarrhea, loss of weight, and injury to kidney and liver (Patnaik, 1992). An irritation concentration of 240.00 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%

16 EC50 (96-h) and EC50 (3-h) concentrations that inhibit the growth of 50% of Selenastrum capricornutum population are 1.6 and 5.2 mg/L, respectively (Calamari et al., 1983). EC50 (48-h) for Pseudokirchneriella subcapitata 3.17 mg/L (Hsieh et al., 2006). IC50 (24-h) for Daphnia magna 1.6 mg/L (Calamari et al., 1983). LC50 (14-d) for Poecilia reticulata 4 mg/L (Könemann, 1981). LC50 (96-h) for fathead minnows 4.0 mg/L (Veith et al., 1983), bluegill sunfish (Lepomis machrochirus) 4.3 mg/L, fathead minnows 30 mg/L (Spehar et al., 1982) and 34.5 mg/L (Curtis et al., 1978), Cyprinodon variegatus 7.4 ppm using natural seawater (Heitmuller et al., 1981). LC50: 17.8 and 51 mg/L (soil porewater concentration) for the earthworm Eisenia andrei and 26 and 229 mg/L (soil porewater concentration) for the earthworm Lumbricus rubellus (Van Gestel and Ma, 1993). LC50 (72-h) for Cyprinodon variegatus 7.4 ppm (Heitmuller et al., 1981). LC50 (48-h) for fathead minnows 35.4 mg/L, grass shrimp 129 mg/L (Curtis et al., 1979), Daphnia magna 11 mg/L (LeBlanc, 1980), 2.2 mg/L (Canton et al., 1985), Salmo gairdneri 1.18 mg/L, Brachydanio rerio 4.25 mg/L (Calamari et al., 1983), Cyprinodon variegatus 7.2 ppm (Heitmuller et al., 1981). LC50 (24-h) for Daphnia magna 42 mg/L (LeBlanc, 1980), fathead minnows 35.4 mg/L (Curtis et al., 1979), fathead minnows 34.0 mg/L (Curtis et al., 1978), Cyprinodon variegatus 7.5 to 10 ppm (Heitmuller et al., 1981). Acute oral LD50 for mice 2,950 mg/kg, rats 500 mg/kg, rabbits 2,830 mg/kg (quoted, RTECS, 1985). Heitmuller et al. (1981) reported a NOEC of 5.6 ppm. Drinking water standard (final): MCLG: 75 µg/L; MCL: 75 µg/L. In addition, a DWEL of 4 mg/L was recommended (U.S. EPA, 2000). Uses: Moth and bird repellent; general insecticide, fumigant and germicide; space odorant; manufacture of 2,5-dichloroaniline and dyes; pharmacy; agriculture (fumigating soil); disinfectant, urinal deodorizer, air freshener, and chemical intermediate in the manufacture of 1,2,4trichlorobenzene and polyphenylene sulfide.