CHLOROPRENE

Cl CASRN: 126-99-8; DOT: 1991; DOT label: Flammable liquid; molecular formula: C4H5Cl; FW: 88.54; RTECS: EI9625000 Physical state, color, and odor: Clear, colorless liquid with a pungent, ether-like odor. The odor threshold is 0.40 mg/m3 (CHRIS, 1984). Melting point (°C): -103 (NIOSH, 1997) Boiling point (°C): 59.4 (Weast, 1986) Density (g/cm3): 0.9583 at 20 °C (Weast, 1986) Diffusivity in water (x 10-5 cm2/sec): 0.93 at 20 °C using method of Hayduk and Laudie (1974) Flash point (°C): -20 (NIOSH, 1997) Lower explosive limit (%): 4.0 (NIOSH, 1997) Upper explosive limit (%): 20.0 (NIOSH, 1997) Henry’s law constant (x 10-2 atm⋅m3/mol): 3.20 using method of Hine and Mookerjee (1975) Ionization potential (eV): 8.79 (NIOSH, 1997) Soil organic carbon/water partition coefficient, log Koc: 1.74 (estimated, Ellington et al., 1993) Octanol/water partition coefficient, log Kow: 2.06 (estimated, Ellington et al., 1993) Solubility in organics: Soluble in acetone, benzene, and ether (Weast, 1986) Vapor density: 3.62 g/L at 25 °C, 3.06 (air = 1)

188 at 20 °C (NIOSH, 1997) 174 at 25 °C (Boublik et al., 1984) 118 at 10 °C, 200 at 20 °C, 275 at 30 °C (quoted, Verschueren, 1983) Environmental fate: Chemical/Physical. Anticipated products from the reaction of chloroprene with ozone or OH radicals in the atmosphere are formaldehyde, 2-chloroacrolein, OHCCHO, ClCOCHO, H2CCHCClO, chlorohydroxy acids, and aldehydes (Cupitt, 1980). Chloroprene will polymerize at room temperature unless inhibited with antioxidants (NIOSH, 1997). Chloroprene is resistant to hydrolysis under neutral and alkaline conditions (Carothers et al., 1931). Chloroprene is subject to hydrolysis forming 3-hydroxypropene and HCl. The reported hydrolysis half-life at 25 °C and pH 7 is 40 yr (Kollig, 1993). Exposure limits: Potential occupational carcinogen. NIOSH REL: 15-min ceiling 1 ppm (3.6 mg/m3), IDLH 300 ppm; OSHA PEL: TWA 25 ppm (90 mg/m3); ACGIH TLV: TWA 10 ppm (adopted). Symptoms of exposure: Irritation of eyes, skin, and respiratory system; dermatitis; nervousness (NIOSH, 1997). Toxicity: Acute oral LD50 for mice 260 mg/kg, rats 900 mg/kg (quoted, RTECS, 1985). Use: Manufacture of neoprene.