2-CHLOROPHENOL

CASRN: 95-57-8; DOT: 2020 (liquid); 2021 (solid); DOT label: Poison; molecular formula: C6H5ClO; FW: 128.56; RTECS: SK2625000; Merck Index: 12, 2206 Physical state, color, and odor: Pale amber liquid with a slight phenolic, floral, or musty-type odor. At 40 °C, the average and lowest odor concentrations detected were 0.36 and 0.088 µg/L, respectively. At 25 °C, the average taste threshold concentration and the lowest concentration at which a taste was detected were 0.97 and 0.94 µg/L, respectively (Young et al., 1996). Melting point (°C): 9.00 (Ma et al., 1993) 7.0 (Stull, 1947) Boiling point (°C): 174.9 (Weast, 1986) 174.5 (Hays et al., 1936) Density (g/cm3): 1.2634 at 20 °C (Weast, 1986) 1.257 at 25 °C (quoted, Krijgsheld and van der Gen, 1986a) Diffusivity in water (x 10-5 cm2/sec): 0.503 (ceff = 70 µM) at 4.0 °C; 0.929 (ceff = 70 µM), 0.923 (ceff = 70 µM), and 0.924 (ceff = 140

µM) at 25.0 °C; 1.654 (ceff = 270 µM) at 50.0 °C (Niesner and Heintz, 2000) Dissociation constant, pKa: 8.56 at 25 °C (quoted, Rosés et al., 2000) 8.30 (Hoigné and Bader, 1983) Flash point (°C): 64 (NFPA, 1984) Entropy of fusion (cal/mol⋅K): 10.58 (Poeti et al., 1982) Heat of fusion (kcal/mol): 2.57 (Tsonopoulos and Prausnitz, 1971) Henry’s law constant (x 10-6 atm⋅m3/mol): 6.44 at 20 °C (Sheikheldin et al., 2001)

9.28 (Franklin et al., 1969) Bioconcentration factor, log BCF: 2.33 (bluegill sunfish, Barrows et al., 1980; Veith et al., 1980) Soil organic carbon/water partition coefficient, log Koc: 1.71 (Brookstone clay loam, Boyd, 1982) 3.69 (fine sediments), 3.60 (coarse sediments) (Isaacson and Frink, 1984) 2.00 (coarse sand), 1.36 (loamy sand) (Kjeldsen et al., 1990) Kd = <0.1 mL/g on a Cs+-kaolinite (Haderlein and Schwarzenbach, 1993) Octanol/water partition coefficient, log Kow: 2.16 at 23 °C (shake flask-LSC, Banerjee et al., 1980; Veith et al., 1980) 2.25 (Menges et al., 1990) 2.17 (Hansch and Leo, 1979) 2.19 (quoted, Leo et al., 1971) 2.15 at 25 °C (shake flask-UV spectrophotometry, Fujita et al., 1964) 2.29 at 20 °C (shake flask-GLC, Kishino and Kobayashi, 1994) 1.56 (estimated from HPLC capacity factors, Eadsforth, 1986) Solubility in organics: Soluble in ethanol, benzene, ether (Weast, 1986), and caustic alkaline solutions (Windholz et al., 1983) Solubility in water: 28,500 mg/L at 20 °C (quoted, Verschueren, 1983) 24,650 mg/L at 20 °C (Mulley and Metcalf, 1966) 22,000 mg/L at 25 °C (Roberts et al., 1977) 11,350 mg/L at 25 °C (shake flask-LSC, Banerjee et al., 1980) 0.2 M at 25 °C (Caturla et al., 1988) 20.838, 22.660, and 24.007 g/L at 15.4, 24.6, and 34.5 °C, respectively (shake flask-

conductimetry, Achard et al., 1996) Vapor density: 5.25 g/L at 25 °C, 4.44 (air = 1) Vapor pressure (mmHg at 25 °C): 1.42 (quoted, Howard, 1989) 2.25 (quoted, Nathan, 1978) Environmental fate: Biological. Chloroperoxidase, a fungal enzyme isolated from Caldariomyces fumago, reacted with 2-chlorophenol yielding traces of 2,4,6-trichlorophenol, 2,4-and 2,6-dichlorophenols (Wannstedt et al., 1990). When 2-chlorophenol was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum, significant biodegradation with rapid adaptation was observed. At concentrations of 5 and 10 mg/L, 86 and 83% biodegradation, respectively, were observed after 7 d (Tabak et al., 1981). Biodegradation rates of 10 and 8 µmol/L⋅d were reported for chlorophenol in saline water and acclimated sulfidogenic sediment cultures (Häggblom and Young, 1990). In activated sludge inoculum, 95.6% COD removal was achieved in 6 h. The average rate of

Soil. In laboratory microcosm experiments kept under aerobic conditions, half-lives of 7.2 and 1.7 d were reported for 2-chlorophenol in an acidic clay soil (<1% organic matter) and slightly basic sandy loam soil (3.25% organic matter) (Loehr and Matthews, 1992). In a nonsterile clay loam soil, a loss of 91% was reported when 2-chlorophenol was incubated in a nonsterile clay loam at 0 °C. Nondetectable levels of 2-chlorophenol was reported in sediments obtained from a stream at 20 °C after 10 to 15 d (Baker et al., 1980). Surface Water. Hoigné and Bader (1983) reported 2-chlorophenol reacts with ozone at a rate constant of 1,100/M⋅sec at the pH range of 1.8 to 4.0. Photolytic. Monochlorophenols exposed to sunlight (UV radiation) produced catechol and other hydroxybenzenes (Hwang et al., 1986). Titanium dioxide suspended in an aqueous solution and irradiated with UV light (λ = 365 nm) converted 2-chlorophenol to carbon dioxide at a significant rate (Matthews, 1986). In a similar experiment, irradiation of an aqueous solution containing 2chlorophenol and titanium dioxide with UV light (λ >340 nm) resulted in the formation of chlorohydroquinone and trace amounts of catechol. Hydroxylation of both of these compounds forms the intermediate hydroxyhydroquinone, which degrades quickly to unidentified carboxylic acids and carbonyl compounds (D’Oliveira et al., 1990). Irradiation of an aqueous solution at 296 nm and pH values from 8 to 13 yielded different products. Photolysis at a pH nearly equal to the dissociation constant (undissociated form) yielded pyrocatechol. At an elevated pH, 2-chlorophenol is almost completely ionized; photolysis yielded cyclopentadienic acid (Boule et al., 1982). Irradiation of an aqueous solution at 296 nm containing hydrogen peroxide converted 2-chlorophenol to catechol and 2-chlorohydroquinone (Moza et al., 1988). In the dark, nitric oxide (10-3 vol %) reacted with 2-chlorophenol forming 4-nitro-2chlorophenol and 6-nitro-2-chlorophenol at yields of 36 and 30%, respectively (Kanno and Nojima, 1979). Chemical/Physical. Wet oxidation of 2-chlorophenol at 320 °C yielded formic and acetic acids (Randall and Knopp, 1980). Wet oxidation of 2-chlorophenol at elevated pressure and temperature yielded the following products: acetone, acetaldehyde, formic, acetic, maleic, oxalic, muconic, and succinic acids (Keen and Baillod, 1985). Chemical oxidation of mono-, di-, and trichlorophenols using Fenton’s reagent were investigated by Barbeni et al. (1987). To a 70-mL aqueous solution containing 2-chlorophenol thermostated at 25.0 °C was added ferrous sulfate and hydrogen peroxide solution (i.e., OH radicals). Concentrations of 2-chlorophenol were periodically determined with time. Though 2chlorophenol degraded quickly, the rate was slower when compared to 3-chlorophenol. The investigators reported that the oxidations of chlorophenols probably proceeds via a hydroxylated compound, followed by ring cleavage yielding aldehydes before mineralizing to carbon dioxide and chloride ions. At a given hydrogen peroxide concentration, when the ferrous ion concentration is increased, the reaction rate also increased when the hydrogen peroxide concentration is constant. Ferric ions alone with hydrogen peroxide did not decrease the concentration of chlorophenols indicating that OH radicals were not formed. The volatilization half-lives of 2-chlorophenol in stirred and static water maintained at 23.8 °C were 1.35 and 1.60 h, respectively (Chiou et al., 1980). In an aqueous phosphate buffer solution at 27 °C, a reaction rate 9.2 x 106/M⋅sec was reported for the reaction with singlet oxygen (Tratnyek and Hoigné, 1991). 2-Chlorophenol will not hydrolyze to any reasonable extent (Kollig, 1993). At influent concentrations of 1.0, 0.1, 0.01, and 0.001 mg/L, the GAC adsorption capacities were 51, 20, 7.9, and 3.1 mg/g, respectively (Dobbs and Cohen, 1980). Toxicity: EC50 (48-h) for Daphnia magna 3.91 mg/L (Keen and Baillod, 1985). EC50 (24-h) for Daphnia pulex 21.0 mg/L (Shigeoka et al., 1988).