ABSTRACT
Note: According to Chevron Phillips Company’s (2004) Technical Data Sheet, 99.0-99.3 wt % 2methylpentane contains 2,3-dimethylbutane (0.5 wt %) and 3-methylpentane (0.2 wt %). CASRN: 107-83-5; DOT: 2462; DOT label: Flammable liquid; molecular formula: C6H14; FW: 86.18; RTECS: SA2995000 Physical state, color, and odor: Clear, colorless, very flammable liquid with an odor similar to hexane. An odor threshold concentration of 8.9 ppmv was reported by Nagata and Takeuchi (1990). Melting point (°C): -153.7 (Weast, 1986) Boiling point (°C): 60.2 (Aucejo et al., 1998) Density (g/cm3): 0.653 at 20 °C (Chevron Phillips, 2004) 0.64843 at 25.00 °C (Bouzas et al., 2000; Muñoz et al., 2000) Diffusivity in water (x 10-5 cm2/sec): 0.75 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: >14 (Schwarzenbach et al., 1993) Flash point (°C): -23.3 (closed cup, Hawley, 1981) -7 (NFPA, 1984) Lower explosive limit (%): 1.2 (NFPA, 1984) Upper explosive limit (%): 7.0 (NFPA, 1984) Heat of fusion (kcal/mol): 1.498 (quoted, Riddick et al., 1986) Henry’s law constant (atm⋅m3/mol): 0.697, 0.694, 0.633, 0.825, and 0.848 at 10, 15, 20, 25, and 30 °C, respectively (EPICS, Ashworth et al., 1988) Interfacial tension with water (dyn/cm): 48.9 at 25 °C (quoted, Freitas et al., 1997)
10.04 (Lias and Liebman, 1998) Soil organic carbon/water partition coefficient, log Koc: Unavailable because experimental methods for estimation of this parameter for aliphatic hydrocarbons are lacking in the documented literature Octanol/water partition coefficient, log Kow: 2.77 (Coates et al., 1985) Solubility in organics: Soluble in acetone, alcohol, benzene, chloroform, and ether (Weast, 1986) Solubility in water: 14.0 mg/L at 23 °C (Coates et al., 1985) In mg/kg: 13.0 at 25 °C, 13.8 at 40.1 °C, 15.7 at 55.7 °C, 27.1 at 99.1 °C, 44.9 at 118.0 °C, 86.8 at
137.3 °C, 113.0 at 149.5 °C (shake flask-GLC, Price, 1976) In mg/kg: 25 at 10 °C, 19 at 20 °C, 16 at 30 °C (shake flask-GC, Howe et al., 1987) 13.8 mg/kg at 25 °C (shake flask-GC, McAuliffe, 1963, 1966) 19.45 mg/kg at 0 °C, 15.7 mg/kg at 25 °C (shake flask-GC, Polak and Lu, 1973) 14.2 mg/L at 25 °C (shake flask-GC, Leinonen and Mackay, 1973) 16.21 mg/L at 25 °C (shake flask-GC, Barone et al., 1966) Vapor density: 3.52 g/L at 25 °C, 2.98 (air = 1) Vapor pressure (mmHg): 211.8 at 25 °C (Wilhoit and Zwolinski, 1971) 338 at 36.8 °C (Aucejo et al., 1998) Environmental fate: Photolytic. When synthetic air containing gaseous nitrous acid and 2-methylpentane was exposed to artificial sunlight (λ = 300-450 nm), acetone, propionaldehyde, peroxyacetal nitrate, peroxypropionyl nitrate, and possibly two isomers of hexyl nitrate and propyl nitrate formed as products (Cox et al., 1980). Based on a photooxidation rate constant of 5.6 x 10-12 cm3/molecule⋅sec for the reaction of 2methylpentane and OH radicals, the atmospheric lifetime is 25 h (Altshuller, 1991). Chemical/Physical: Complete combustion in air yields carbon dioxide and water vapor. 2Methylpentane will not hydrolyze because it does not contain a hydrolyzable functional group. Exposure limits: ACGIH TLV: TWA and STEL for all isomers except n-hexane are 500 and 1,000 ppm, respectively (adopted). Symptoms of exposure: Inhalation of vapors may cause irritation of respiratory tract (Patnaik, 1992) Source: Schauer et al. (1999) reported 2-methylpentane in a diesel-powered medium-duty truck exhaust at an emission rate of 930 µg/km. A constituent in gasoline. Harley et al. (2000) analyzed the headspace vapors of three grades of unleaded gasoline where ethanol was added to replace methyl tert-butyl ether. The gasoline vapor concentrations of 2-methylpentane in the headspace were 9.3 wt % for regular grade, 9.8 wt % for
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 2-methylpentane was 8.6 mg/kg of pine burned. Emission rates of 2-methylpentane were not measured during the combustion of oak and eucalyptus. California Phase II reformulated gasoline contained 2-methylpentane at a concentration of 36.9 g/kg. Gas-phase tailpipe emission rates from gasoline-powered automobiles with and without catalytic converters were 6.31 and 827 mg/km, respectively (Schauer et al., 2002). Reported as an impurity (0.1 wt %) in 99.0-99.7 wt % 2,3-dimethylbutane (Chevron Phillips, 2004). Uses: Solvent; gasoline component; organic synthesis.
