HEPTANE

CH3H3C Note: According to Chevron Phillips Company’s (2005) Technical Data Sheet, 99.0-99.4 wt % nheptane (pure grade) contains the following components: cis-1,2-dimethylcyclopentane + methylcyclohexane (≤ 1 wt %), trans-1,2-dimethylcyclopentane (≤ 0.25 wt %), 3-methylhexane (≤ 0.25 wt %), sulfur content (≤ 1 wt %), and the largest other single impurity at a concentration of (≤ 0.15 wt %). CASRN: 142-82-5; DOT: 1206; DOT label: Flammable liquid; molecular formula: C7H16; FW: 100.20; RTECS: MI7700000; Merck Index: 12, 4694 Physical state, color, and odor: Clear, colorless, very flammable liquid with a faint, pleasant odor resembling hexane or octane. Based on a triangle bag odor method, an odor threshold concentration of 670 ppbv was reported by Nagata and Takeuchi (1990). Melting point (°C): -90.6 (Weast, 1986) Boiling point (°C): 98.40 (Tu et al., 2001) 96.30 (Vittal Prasad et al., 2001) Density (g/cm3): 0.68789 at 15.00 °C, 0.67951 at 25.00 °C, 0.67088 at 35.00 °C (Calvo et al., 1998) 0.68374 at 20.00 °C, 0.66692 at 30.00 °C (Hahn and Svejda, 1996) 0.6794 at 25.00 °C, 0.6756 at 30.00 °C, 0.6660 at 35.00 °C (Sastry and Raj, 1996) 0.6665 at 40.00 °C, 0.6577 at 50.00 °C, 0.6487 at 60.00 °C (Kahl et al., 2003) 0.6712 at 35.00 °C, 0.6623 at 45.00 °C (Sastry et al., 1999) Diffusivity in water (x 10-5 cm2/sec): 0.71 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: >14 (Schwarzenbach et al., 1993) Flash point (°C): -3.9 (NIOSH, 1997) -1 (Affens and McLaren, 1972) Lower explosive limit (%): 1.05 (NIOSH, 1997) Upper explosive limit (%): 6.7 (NIOSH, 1997) Heat of fusion (kcal/mol): 3.355 (quoted, Riddick et al., 1986)

0.901, 1.195, and 1.905 at 26.0, 35.8, and 45.0 °C, respectively (dynamic headspace, Hansen et al., 1995) Interfacial tension with water (dyn/cm): 50.2 at 25 °C (Donahue and Bartell, 1952) 51.39 at 25 °C (Jańczuk et al., 1993) 51.23 at 20 °C (Fowkes, 1980) 51.9 at 22 °C (Goebel and Lunkenheimer, 1997) 51.59 at 15.0 °C, 51.24 at 20.0 °C, 50.71 at 25.0 °C, 50.47 at 27.5 °C, 50.30 at 30.0 °C, 50.12 at

32.5 °C, 49.89 at 35.0 °C, 49.64 at 37.5 °C, 49.38 at 40.0 °C, 49.00 at 45.0 °C, 48.55 at 50.0 °C (Zeppieri et al., 2001)

49.50 at 25.00 °C (Fu et al., 2000) Ionization potential (eV): 9.90 (Franklin et al., 1969) Soil organic carbon/water partition coefficient, log Koc: Unavailable because experimental methods for estimation of this parameter for alkenes are lacking in the documented literature Octanol/water partition coefficient, log Kow: 4.73 at 25.0 °C (generator column-RPLC, Schantz and Martire, 1987) 4.66 (generator column-HPLC, Tewari et al., 1982; generator column-HPLC/GC, Wasik et al.,

1981) Solubility in organics: In methanol, g/L: 181 at 5 °C, 200 at 10 °C, 225 at 15 °C, 254 at 20 °C, 287 at 25 °C, 327 at 30

°C, 378 at 35 °C, 450 at 40 °C (Kiser et al., 1961). Miscible with many liquid hydrocarbons, e.g., pentane, hexane, etc. Solubility in water: 2.24 mg/kg at 25 °C, 2.63 mf/kf at 40.1 °C, 3.11 mg/kg at 55.7 °C (shake flask-GLC, Price, 1976) 2.93 mg/kg at 25 °C (shake flask-GC, McAuliffe, 1963, 1966) 4.39 mg/kg at 0 °C, 3.37 mg/kg at 25 °C (shake flask-GC, Polak and Lu, 1973) 35.7 µmol/L at 25.0 °C (generator column-HPLC, Tewari et al., 1982; generator column-

HPLC/GC, Wasik et al., 1981) 2.19-2.66 mg/L at 25 °C (shake flask-fluorescence, Mackay and Shiu, 1981) 0.07 mL/L at 15.5 °C (shake flask-turbidimetric, Fühner, 1924) 2.9 mg/L (shake flask-GC, Coutant and Keigley, 1988) 70 mg/kg at 25 °C (shake flask-turbidimetric, Stearns et al., 1947) In mole fraction (x-7): 3.51, 3.63, 4.78, 4.07, and 4.32 at 4.3, 13.5, 25.0, 35.0, and 45.0 °C,

respectively (shake flask-GC, Nelson and de Ligny, 1968) In mole fraction (x 10-6): 0.474 at 32.7 °C, 0.915 at 70.4 °C, 2.08 at 100.7 °C, 4.00 at 131.0 °C, 8.8

at 151.3 °C, 17.63 at 170.5 °C, and 17.42 at 170.6 °C (equilibrium cell-HPLC, Marche et al., 2003)

5 x 10-7 in seawater at 25 °C (mole fraction, shake flask-GC, Krasnoshchekova and Gubergrits, 1973)

Vapor density: 4.10 g/L at 25 °C, 3.46 (air = 1)

35 at 20 °C (quoted, Verschueren, 1983) 46 at 25 °C (Milligan, 1924) 45.61 at 25.00 °C (del Rio et al., 2001) 44.69 at 25.00 °C (GC, Hussam and Carr, 1985) 14.8, 25.0, 45.7, 73.8, and 114.9 at 4.3, 13.5, 25.0, 35.0, and 45.0 °C, respectively (Nelson and de

Ligny, 1968) 58.6 at 30.00 °C, 141.5 at 50.00 °C (Carmona et al., 2000) 92.3 at 40.00 °C (Rhodes et al., 1997) Environmental fate: Biological. Heptane may biodegrade in two ways. The first is the formation of heptyl hydroperoxide, which decomposes to 1-heptanol followed by oxidation to heptanoic acid. The other pathway involves dehydrogenation to 1-heptene, which may react with water forming 1heptanol (Dugan, 1972). Microorganisms can oxidize alkanes under aerobic conditions (Singer and Finnerty, 1984). The most common degradative pathway involves the oxidation of the terminal methyl group forming the corresponding alcohol (1-heptanol). The alcohol may undergo a series of dehydrogenation steps forming heptanal followed by oxidation forming heptanoic acid. The acid may then be metabolized by β-oxidation to form the mineralization products, carbon dioxide and water (Singer and Finnerty, 1984). Hou (1982) reported hexanoic acid as a degradation product by the microorganism Pseudomonas aeruginosa. Photolytic. The following rate constants were reported for the reaction of hexane and OH radicals in the atmosphere: 7.15 x 10-12 cm3/molecule⋅sec (Atkinson, 1990). Photooxidation reaction rate constants of 7.19 x 10-12 and 1.36 x 10-16 cm3/molecule⋅sec were reported for the reaction of heptane with OH and NO3, respectively (Sabljić and Güsten, 1990). Based on a photooxidation rate constant 7.15 x 10-12 cm3/molecule⋅sec for heptane and OH radicals, the estimated atmospheric lifetime is 19 h in summer sunlight (Altshuller, 1991). Chemical/Physical. Complete combustion in air yields carbon dioxide and water vapor. Heptane will not hydrolyze because it has no hydrolyzable functional group. Exposure limits: NIOSH REL: TWA 85 ppm (350 mg/m3), 15-min ceiling 440 ppm (1,800 mg/m3), IDLH 750 ppm; OSHA PEL: TWA 500 ppm (2,000 mg/m3); ACGIH TLV: TWA 400 ppm, STEL 500 ppm (adopted). Symptoms of exposure: May cause nausea and dizziness and may impart a gasoline-like taste (Patnaik, 1992) Toxicity: LD50 (24-h) for goldfish 4 mg/L (quoted, Verschueren, 1983). LD50 (intravenous) for mice 222 mg/kg (quoted, RTECS, 1985). Source: Schauer et al. (1999) reported heptane in a diesel-powered medium-duty truck exhaust at an emission rate of 470 g/km. Identified as one of 140 volatile constituents in used soybean oils collected from a processing plant that fried various beef, chicken, and veal products (Takeoka et al., 1996). 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 heptane was 28.9 mg/kg of pine burned. Emission rates of heptane were not measured during the combustion of oak and eucalyptus. California Phase II reformulated gasoline contained heptane at a concentration of 9,700 mg/kg.