OCTANE

Note: According to Chevron Phillips Company’s (2004) Technical Data Sheet, 97.0-98.5 wt % octane typically contains 1.5 wt % isooctanes, <1 ppm sulfur content, and trace amounts of isononanes. CASRN: 111-65-9; DOT: 1262; DOT label: Flammable liquid; molecular formula: C8H18; FW: 114.23; RTECS: RG8400000; Merck Index: 12, 6847 Physical state, color, and odor: Clear, colorless, flammable liquid with a gasoline-like odor. An odor threshold concentration of 1.7 ppmv was reported by Nagata and Takeuchi (1990). Melting point (°C): -56.84 (Ralston et al., 1944) Boiling point (°C): 125.84 (Fuangfoo et al., 1999) 125.66 (Stephenson and Malanowski, 1987) Density (g/cm3): 0.70651 at 15.00 °C, 0.69847 at 25.00 °C, 0.69031 at 35.00 °C (Calvo et al., 1998) 0.7026 at 20.00 °C, 0.6986 at 25.00 °C (Nhaesi and Asfour, 2000) 0.69848 at 25.00 °C, 0.68628 at 40.00 °C (Comelli et al., 1996) 0.6906 at 35.00 °C (Aminabhavi and Patil, 1997) 0.68628 at 40.00 °C (Comelli et al., 1996) Diffusivity in water (x 10-5 cm2/sec): 0.66 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: >14 (Schwarzenbach et al., 1993) Flash point (°C): 13.4 (NIOSH, 1997) 48 (Affens and McLaren, 1972) Lower explosive limit (%): 1.0 (NIOSH, 1997) Upper explosive limit (%): 6.5 (NIOSH, 1997) 4.7 (Sax and Lewis, 1987) Entropy of fusion (cal/mol⋅K): 22.27 (Parks et al., 1930) 22.9 (Huffman et al., 1931) 22.91 (Finke et al., 1954)

4.802 (Parks et al., 1930) 4.936 (Huffman et al., 1931) 4.957 (Finke et al., 1954) Henry’s law constant (atm⋅m3/mol): 4.45 at 25 °C (Jönsson et al., 1982) Interfacial tension with water (dyn/cm): 50.2 at 25 °C (Donahue and Bartell, 1952) 51.68 at 20 °C (Fowkes, 1980) 50.81 at 20 °C (Harkins et al., 1920) 52.5 at 22 °C (Goebel and Lunkenheimer, 1997) 51.09 at 25 °C (Jańczuk et al., 1993) 52.27 at 10.0 °C, 52.01 at 15.0 °C, 51.64 at 20.0 °C, 51.16 at 27.5 °C, 51.00 at 25.0 °C, 50.74 at

30.0 °C, 50.48 at 32.5 °C, 50.22 at 35.0 °C, 50.09 at 37.5 °C, 49.84 at 40.0 °C, 49.45 at 45.0 °C, 48.95 at 50.0 °C, 48.58 at 55.0 °C, 48.32 at 60.0 °C (Zeppieri et al., 2001)

Ionization potential (eV): 9.80 (Lias, 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: 4.00 (Coates et al., 1985) 5.24 at 25 °C (generator column-RPLC, Schantz and Martire, 1987) 5.18 at 25 °C (generator column-HPLC, Tewari et al., 1982; generator column-HPLC/GC, Wasik

et al., 1981) Solubility in organics: In methanol, g/L: 122 at 5 °C, 136 at 10 °C, 152 at 15 °C, 167 at 20 °C, 184 at 25 °C, 206 at 30 °C, 230 at 35 °C, 260 at 40 °C (Kiser et al., 1961) Solubility in water: In mg/kg: 0.431 at 25 °C, 0.524 at 40.1 °C, 0.907 at 69.7 °C, 1.12 at 99.1 °C, 4.62 at 121.3 °C,

8.52 at 136.6 °C, 11.8 at 149.5 °C (shake flask-GLC, Price, 1976) 0.66 mg/kg at 25 °C (Coates et al., 1985; shake flask-GC, McAuliffe, 1963, 1966) 1.35 mg/kg at 0 °C, 0.85 mg/kg at 25 °C (shake flask-GC, Polak and Lu, 1973) 0.884 mg/L at 20 °C, 1.66 mg/L at 70 °C (Burris and MacIntyre, 1986) 9.66 µmol/L at 25.0 °C (generator column-HPLC, Tewari et al., 1982; generator column-

HPLC/GC, Wasik et al., 1981) 0.493 and 0.88 mg/L at 25 °C (shake flask-fluorescence, Mackay and Shiu, 1981) 0.02 mL/L at 16 °C (shake flask-turbidimetric, Fühner, 1924) 0.090 mL/L of water containing 0.1 wt % sodium naphthenate (Baker, 1980) 1.25 mg/L (shake flask-GC, Coutant and Keigley, 1988) In mole fraction (x 107): 2.6, 1.4, and 2.9 at 5.0, 25.0, and 45.0 °C, respectively (Nelson and de

Ligny, 1968) 10-7 at 25 °C (mole fraction, shake flask-GC, Krasnoshchekova and Gubergrits, 1973) In mole fraction (x 10-6): 0.122 at 29.9 °C, 0.120 at 30.3 °C, 0.239 at 69.2 °C, 0.352 at 70.0 °C,

165.1 °C, 6.82 at 165.4 °C, 13.37 at 183.0 °C (equilibrium cell-HPLC, Marche et al., 2003)

0.615 mg/L at 25 °C (Jönsson et al., 1982) 660 µg/L at 25 °C (shake flask-GC, Tolls et al., 2002) In mmol/L: 7.55 at 10.3 °C, 6.87 at 24.8 °C, 6.84 at 24.9 °C, 8.13 at 34.9 °C, 8.20 at 39.9 °C, 8.67

at 44.7 °C (saturation column-GC, Sarraute et al., 2004) Vapor density: 4.67 g/L at 25 °C, 3.94 (air = 1) Vapor pressure (mmHg): 26.0 at 36.98 °C (Plesnar et al., 1996) 9.4 at 18.1 °C, 10.9 at 20.7 °C, 13.6 at 24.6 °C, 16.0 at 27.4 °C, 18.1 at 29.6 °C (Dejoz et al.,

1996b) 14.14 at 25 °C (Wilhoit and Zwolinski, 1971) 10.37 at 20 °C, 118.4 at 70 °C (Burris and MacIntyre, 1986) 13.60 at 25.00 °C (GC, Hussam and Carr, 1985) 4.2, 14.0, and 39.8 at 5.0, 25.0, and 45.0 °C, respectively (Nelson and de Ligny, 1968) Environmental fate: Biological. n-Octane may biodegrade in two ways. This first is the formation of octyl hydroperoxide, which decomposes to 1-octanol followed by oxidation to octanoic acid. The other pathway involves dehydrogenation to 1-octene, which may react with water giving 1-octanol (Dugan, 1972). 1-Octanol was reported as the biodegradation product of octane by a Pseudomonas sp. (Riser-Roberts, 1992). 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-octanol). The alcohol may undergo a series of dehydrogenation steps forming an aldehyde (octanal) then a fatty acid (octanoic acid). The fatty acid may then be metabolized by β-oxidation to form the mineralization products, carbon dioxide and water (Singer and Finnerty, 1984). Photolytic. The following rate constants were reported for the reaction of octane and OH radicals in the atmosphere: 5.1 x 10-12 cm3/molecule⋅sec at 300 K (Hendry and Kenley, 1979); 1.34 x 10-12 cm3/molecule⋅sec (Greiner, 1970); 8.40 x 10-12 cm3/molecule⋅sec (Atkinson et al., 1979), 8.42 x 10-12 cm3/molecule⋅sec at 295 K (Darnall et al., 1978). Photooxidation reaction rate constants of 8.71 x 10-12 and 1.81 x 10-18 cm3/molecule⋅sec were reported for the reaction of octane with OH and NO3, respectively (Sabljić and Güsten, 1990). Surface Water. Mackay and Wolkoff (1973) estimated an evaporation half-life of 3.8 sec from a surface water body that is 25 °C and 1 m deep. Chemical/Physical. Complete combustion in air produces carbon dioxide and water vapor. Octane will not hydrolyze because it does not contain a hydrolyzable functional group. Exposure limits: NIOSH REL: TWA 75 ppm (350 mg/m3), 15-min ceiling 385 ppm (1,800 mg/m3), IDLH 1,000 ppm; OSHA PEL: TWA 500 ppm (2,350 mg/m3); ACGIH TLV: TWA 300 ppm (adopted). Symptoms of exposure: Irritates mucous membranes. Narcotic at high concentrations (Patnaik, 1992). An irritation concentration of 1,450.00 mg/m3 in air was reported by Ruth (1986). Source: Schauer et al. (1999) reported octane in a diesel-powered medium-duty truck exhaust at an emission rate of 260 µg/km. Identified as one of 140 volatile constituents in used soybean oils collected from a processing

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 octane was 1.7 mg/kg of pine burned. Emission rates of octane were not measured during the combustion of oak and eucalyptus. California Phase II reformulated gasoline contained octane at a concentration of 6.38 g/kg. Gasphase tailpipe emission rates from gasoline-powered automobiles with and without catalytic converters were 1.07 and 131 mg/km, respectively (Schauer et al., 2002). Uses: Solvent; rubber and paper industries; calibrations; azeotropic distillations; occurs in gasoline and petroleum naphtha; organic synthesis.