CYCLOPENTENE

CASRN: 142-29-0; DOT: 2246; molecular formula: C5H8; FW: 68.12; RTECS: GY5950000 Physical state, color, and odor: Clear, colorless, watery, very flammable liquid with a characteristic sweet, petroleum-like odor. Melting point (°C): -135.08 (Dreisbach, 1959) Boiling point (°C): 44.2 (Weast, 1986) Density (g/cm3): 0.77199 at 20 °C, 0.76653 at 25 °C (Dreisbach, 1959) Diffusivity in water (x 10-5 cm2/sec): 0.95 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: >14 (Schwarzenbach et al., 1993) Flash point (°C): -30 (Acros Organics, 2002) Heat of fusion (kcal/mol): 0.804 (Dean, 1987) Henry’s law constant (x 10-2 atm⋅m3/mol): 6.3 at 25 °C (Hine and Mookerjee, 1975) Ionization potential (eV): 9.01 (Franklin et al., 1969) 9.27 (Collin and Lossing, 1959) Soil organic carbon/water partition coefficient, log Koc: Unavailable because experimental methods for estimation of this parameter for alicyclic hydrocarbons are lacking in the documented literature Octanol/water partition coefficient, log Kow: 2.45 using method of Hansch et al. (1968) Solubility in organics: Soluble in alcohol, benzene, ether, and petroleum (Weast, 1986) Solubility in water: 535 mg/kg at 25 °C (shake flask-GC, McAuliffe, 1966)

titration, Natarajan and Venkatachalam, 1972)

Vapor density: 2.78 g/L at 25 °C, 2.35 (air = 1) Vapor pressure (mmHg): 380 at 25 °C (estimated using Antoine equation, Dreisbach, 1959) Environmental fate: Biological. Cyclopentene may be oxidized by microbes to cyclopentanol, which may oxidize to cyclopentanone (Dugan, 1972). Photolytic. The following rate constants were reported for the reaction of cyclopentene with OH radicals in the atmosphere: 6.39 x 10-11 cm3/molecule⋅sec (Atkinson et al., 1983), 4.99 x 10-11 cm3/molecule⋅sec at 298 K (Rogers, 1989), 4.0 x 10-10 cm3/molecule⋅sec (Atkinson, 1990) and 6.70 x 10-11 cm3/molecule⋅sec (Sabljić and Güsten, 1990); with ozone in the atmosphere: 8.13 x 10-16 at 298 K (Japar et al., 1974) and 9.69 x 10-16 cm3/molecule⋅sec at 294 K (Adeniji et al., 1981); with NO3 in the atmosphere: 4.6 x 10-13 cm3/molecule⋅sec at 298 K (Atkinson, 1990) and 5.81 x 10-13 cm3/molecule⋅sec at 298 K (Sabljić and Güsten, 1990). Chemical/Physical. Gaseous products formed from the reaction of cyclopentene with ozone were (% yield): formic acid (11), carbon monoxide (35), carbon dioxide (42), ethylene (12), formaldehyde (13), and butanal (11). Particulate products identified include succinic acid, glutaraldehyde, 5-oxopentanoic acid, and glutaric acid (Hatakeyama et al., 1987). At elevated temperatures, rupture of the C-C bond occurs forming molecular hydrogen and cyclopentadiene (95% yield) as the principal products (Rice and Murphy, 1942). Toxicity: Acute oral LD50 for rats is 1,656 mg/kg (quoted, RTECS, 1985). Source: Schauer et al. (2001) measured organic compound emission rates for volatile organic compounds, gas-phase semi-volatile organic compounds, and particle-phase organic compounds from the residential (fireplace) combustion of pine, oak, and eucalyptus. The gas-phase emission rate of cyclopentene was 7.8 mg/kg of pine burned. Emission rates of cyclopentene were not measured during the combustion of oak and eucalyptus. California Phase II reformulated gasoline contained cyclopentene at a concentration of 1,120 mg/kg. Gas-phase tailpipe emission rates from gasoline-powered automobiles with and without catalytic converters were 480 and 31,700 µg/km, respectively (Schauer et al., 2002). Given that cyclopentene is prepared from cyclohepentanol, the latter may be present as an impurity. Uses: Cross-linking agent; organic synthesis; solvent; extracting agent.