ABSTRACT
Cl CH3 CASRN: 74-87-3; DOT: 1063; DOT label: Flammable gas; molecular formula: CH3Cl; FW: 50.48; RTECS: PA6300000; Merck Index: 12, 6121 Physical state, color, and odor: Colorless, liquefied compressed gas, with a sweet, ethereal odor. Volatile flammable gas. An experimentally determined odor threshold concentration of >100 ppmv was reported by Leonardos et al. (1969). Melting point (°C): -97.1 (Weast, 1986) -97.6 (McGovern, 1943) Boiling point (°C): -24.22 (Dreisbach, 1959) -23.76 (McGovern, 1943) Density (g/cm3 at 20 °C): 0.9214 (quoted, Riddick et al., 1986) Diffusivity in water (x 10-5 cm2/sec): 1.49 at 25 °C (quoted, Hayduk and Laudie, 1974) Flash point (°C): -50 (NFPA, 1984) Lower explosive limit (%): 8.1 (NIOSH, 1997) Upper explosive limit (%): 17.4 (NIOSH, 1997) Heat of fusion (kcal/mol): 1.537 (quoted, Riddick et al., 1986) Henry’s law constant (x 10-3 atm⋅m3/mol): 7.69 at 20 °C (McConnell et al., 1975; Pearson and McConnell, 1975) 8.33 at 25 °C (EPICS, Gossett, 1987) 9.41 (Glew and Moelwyn-Hughes, 1953) 6.6 (low ionic strength, Pankow and Rosen, 1988) 10.64 at 25 °C; in seawater: 3.9, 4.6, and 5.3 at 0, 3, and 6 °C, respectively (Moore et al., 1995) In seawater: 5.22 at 5 °C, 6.36 at 10 °C, 8.72 at 15 °C, 9.35 at 20 °C, 11.20 at 25 °C (Moore,
2000) Interfacial tension with water (dyn/cm at 20 °C): 28.3 (quoted, Freitas et al., 1997)
11.33 (Gibson, 1977) Soil organic carbon/water partition coefficient, log Koc: 0.78 (Jury et al., 1990) Octanol/water partition coefficient, log Kow: 0.91 (Hansch et al., 1975) Solubility in organics: Miscible with chloroform, ether, glacial acetic acid (U.S. EPA, 1985), and other chlorinated hydrocarbons including carbon tetrachloride. Solubility in water: 7.4 g/kg at 30 °C (McGovern, 1943) 6,450 to 7,250 mg/L at 20 °C (Pearson and McConnell, 1975) 5,350 mg/L at 25.01 °C (Glew and Moelwyn-Hughes, 1953) 4,800 mg/L at 25 °C (quoted, Standen, 1964) In mmol/atm: 167 at 10.2 °C, 97.9 at 23.5 °C, 71.4 at 36.9 °C, 69.1 at 37.4 °C, 45.2 at 59.2 °C
(Boggs and Buck, 1958) Vapor density: 2.06 g/L at 25 °C, 1.74 (air = 1) Vapor pressure (mmHg): 3,756 at 20 °C (McConnell et al., 1975) 4,028 at 25 °C (quoted, Nathan, 1978) 4,962 at 30 °C, 7,313 at 50 °C (Hsu et al., 1964) 4,309.7 at 30 °C (quoted, Howard, 1989) Environmental fate: Biological. Enzymatic degradation of methyl chloride yielded formaldehyde (Vogel et al., 1987). Photolytic. Reported photooxidation products via OH radicals include formyl chloride, carbon monoxide, hydrogen chloride, and phosgene (Spence et al., 1976). In the presence of water, formyl chloride hydrolyzes to HCl and carbon monoxide, whereas phosgene hydrolyzes to hydrogen chloride and carbon monoxide (Morrison and Boyd, 1971). Methyl chloride reacts with OH radicals in the atmosphere at a rate of 8.5 x 10-14 cm3/sec with a lifetime of 135 d (Cox et al., 1976). Chemical/Physical. The estimated hydrolysis half-life at 25 °C and pH 7 is 0.93 yr (Mabey and Mill, 1978). The evaporation half-life of methyl chloride (1 mg/L) from water at 25 °C using a shallow-pitch propeller stirrer at 200 rpm at an average depth of 6.5 cm was 27.6 min (Dilling, 1977). Exposure limits: Potential occupational carcinogen. NIOSH REL: IDLH 2,000 ppm; OSHA PEL: TWA 100 ppm, ceiling 200 ppm, 5-min/3-h peak 300 ppm; ACGIH TLV: TWA 50 ppm, STEL 100 ppm (adopted). Symptoms of exposure: Inhalation of vapors may cause headache, dizziness, drowsiness, nausea, vomiting, convulsions, coma, and respiratory failure (Patnaik, 1992). An irritation concentration of 1,050.00 mg/m3 in air was reported by Ruth (1986).
