ABSTRACT
CYCLOPENTANE Synonyms: BRN 1900195; Cyclopentamethylene; EINECS 206-016-6; EINECS 270-696-0; NSC 60213; Pentamethylene; UN 1146.
Note: According to Chevron Phillips Company’s (2004) product literature, 99.0-99.5% cyclopentane contains the following compounds: n-pentane (0.2 wt %), 2,2-dimethylbutane (0.1 wt %), and methylcyclopentane (0.2 wt %). CASRN: 287-92-3; DOT: 1146; DOT label: Flammable liquid; molecular formula: C5H10; FW: 70.13; RTECS: GY2390000; Merck Index: 12, 2809 Physical state and color: Colorless, mobile, flammable liquid with an odor resembling cyclohexane. Melting point (°C): -93.9 (Weast, 1986) Boiling point (°C): 49.20 (Cheng et al., 1997) Density (g/cm3): 0.76512 at 0.00 °C, 0.7620 at 5.00 °C, 0.75532 at 10.00 °C, 0.75027 at 15.00 °C, 0.74502 at 20.00
°C, 0.73863 at 25.00 °C, 0.73197 at 30.00 °C (Ma et al., 2003) Diffusivity in water (x 10-5 cm2/sec): 0.93 at 20 °C (Witherspoon and Bonoli, 1969) 1.04 at 25 °C (Bonoli and Witherspoon, 1968) Dissociation constant, pKa: ≈ 44 (Gordon and Ford, 1972) Flash point (°C): -37.2 (NIOSH, 1997) Lower explosive limit (%): 1.1 (NIOSH, 1997) Upper explosive limit (%): 8.7% (NIOSH, 1997) Heat of fusion (kcal/mol): 0.1455 (quoted, Riddick et al., 1986) Henry’s law constant (atm⋅m3/mol): 0.164, 0.240, and 0.300 at 27.9, 35.8, and 45.0 °C, respectively (dynamic headspace, Hansen et al., 1995) Interfacial tension with water (dyn/cm at 20 °C): 28 (CHRIS, 1984)
10.53 ± 0.05 (Franklin et al., 1969) 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: 3.00 (Leo et al., 1975) Solubility in organics: Miscible with ether and other hydrocarbon solvents (Windholz et al., 1983), such as pentane,
hexane, and cyclohexane. In methanol, g/L: 680 at 5 °C, 860 at 10 °C, 1,400 at 15 °C. Miscible at higher temperatures (Kiser
et al., 1961). Solubility in water: In mg/kg: 160 at 25 °C, 163 at 40.1 °C, 180 at 55.7 °C, 296 at 99.1 °C, 372 at 118.0 °C, 611 at
137.3 °C, 792 at 153.1 °C (shake flask-GLC, Price, 1976) 156 mg/kg at 25 °C (shake flask-GC, McAuliffe, 1963, 1966) 164 mg/L at 25 °C, 128 mg/L in artificial seawater (34.5 parts NaCl per 1,000 parts water) at 25
°C (Groves, 1988) Vapor density: 2.87 g/L at 25 °C, 2.42 (air = 1) Vapor pressure (mmHg): 400 at 31.0 °C (estimated, Weast, 1986) Environmental fate: Biological. Cyclopentane 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 octane and OH radicals in the atmosphere: 3.7 x 10-12 cm3/molecule⋅sec at 300 K (Hendry and Kenley, 1979); 5.40 x 10-12 cm3/molecule⋅sec (Atkinson, 1979); 4.83 x 10-12 cm3/molecule⋅sec at 298 K (DeMore and Bayes, 1999); 6.20 x 10-12, 5.24 x 10-12, and 4.43 x 10-12 cm3/molecule⋅sec at 298, 299, and 300 K, respectively (Atkinson, 1985), 5.16 x 10-12 cm3/molecule⋅sec at 298 K (Atkinson, 1990), and 5.02 x 10-12 cm3/mol·sec at 295 K (Droege and Tilly, 1987). Chemical/Physical. Cyclopentane will not hydrolyze because it has no hydrolyzable functional group. Complete combustion in air yields carbon dioxide and water. At elevated temperatures, rupture of the ring occurs forming ethylene and presumably allene and hydrogen (Rice and Murphy, 1942). Exposure limits: NIOSH REL: 600 ppm (1,720 mg/m3); ACGIH TLV: TWA 600 ppm (adopted). Symptoms of exposure: Exposure to high concentrations may produce depression of central nervous system. Symptoms include excitement, loss of equilibrium, stupor, and coma (Patnaik, 1992). Source: Component of high octane gasoline (quoted, Verschueren, 1983). Harley et al. (2000) analyzed the headspace vapors of three grades of unleaded gasoline where ethanol was added to
% in the headspace vapors for regular, mid-, and premium grades. Schauer et al. (1999) reported cyclopentane in a diesel-powered medium-duty truck exhaust at an emission rate of 410 µg/km. California Phase II reformulated gasoline contained cyclopentane at a concentration of 4.11 g/kg. Gas-phase tailpipe emission rates from gasoline-powered automobiles with and without catalytic converters were 0.78 and 85.4 mg/km, respectively (Schauer et al., 2002). Uses: Solvent for cellulose ethers and paints; azeotropic distillation agent; motor fuel; extractions of fats and wax; shoe industry; organic synthesis.
