ABSTRACT

CASRN: 110-83-8; DOT: 2256; DOT label: Flammable liquid; molecular formula: C6H10; FW: 82.15; RTECS: GW2500000; Merck Index: 12, 2796 Physical state, color, and odor: Clear, colorless liquid with a sweet odor. Odor threshold concentration is 0.18 ppm (quoted, Amoore and Hautala, 1983). Melting point (°C): -103.5 (Weast, 1986) Boiling point (°C): 83 (Weast, 1986) Density (g/cm3): 0.81096 at 20 °C, 0.80609 at 25 °C (Dreisbach, 1959) 0.7823 at 50 °C (Windholz et al., 1983) Diffusivity in water (x 10-5 cm2/sec): 0.88 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: >14 (Schwarzenbach et al., 1993) Flash point (°C): -20 (BASF, 1997a) Heat of fusion (kcal/mol): 0.787 (Dean, 1987) Henry’s law constant (x 10-2 atm⋅m3/mol): 3.85 at 25 °C (Nielsen et al., 1994) Ionization potential (eV): 8.72 (Franklin et al., 1969) 9.18 (Collin and Lossing, 1959) 9.20 (Rav-Acha et al., 1987) 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: 2.86 (Hansch and Leo, 1979)

Soluble in acetone, alcohol, benzene, and ether (Weast, 1986). Solubility in water: 130 mg/L at 25 °C (shake flask-gravimetric, McBain and Lissant, 1951) 213 mg/kg at 25 °C (shake flask-GC, McAuliffe, 1966) 281, 286 mg/kg at 23.5 °C (elution chromatography, Schwarz, 1980) Based on an average reported value of 1.21 x 10-4 lb. mole/ft3 at 25 °C, the solubility is 0.16 wt %

(vapor pressure apparatus, Farkas, 1965) In 1 mM nitric acid: 4.95, 3.46, and 2.49 mM at 30, 35, and 40 °C, respectively (Natarajan and

Venkatachalam, 1972) Vapor density: 3.36 g/L at 25 °C, 2.84 (air = 1) Vapor pressure (mmHg): 67 at 20 °C (NIOSH, 1997) 88.8 at 25 °C (estimated using Antoine equation, Dreisbach, 1959) Environmental fate: Biological. Cyclohexene biodegrades to cyclohexanone (Dugan, 1972; Verschueren, 1983). Photolytic. The following rate constants were reported for the reaction of cyclohexene with OH radicals in the atmosphere: 6.80 x 10-11 cm3/molecule⋅sec (Atkinson et al., 1979), 6.75 x 10-11 cm3/molecule⋅sec at 298 K (Sabljić and Güsten, 1990), 5.40 x 10-11 cm3/molecule⋅sec at 298 K (Rogers, 1989), 1.0 x 10-10 cm3/molecule⋅sec at 298 K (Atkinson, 1990); with ozone in the gasphase: 1.69 x 10-16 cm3/molecule⋅sec at 298 K (Japar et al., 1974), 2.0 x 10-16 at 294 K (Adeniji et al., 1981), 1.04 x 10-16 cm3/molecule⋅sec (Atkinson et al., 1983), 1.04 x 10-16 at 298 K (Atkinson and Carter, 1984); with NO3 in the atmosphere: 5.26 x 10-13 cm3/molecule⋅sec (Sabljić and Güsten, 1990); 5.3 x 10-13 cm3/molecule⋅sec at 298 K (Atkinson, 1990), and 5.28 x 10-13 cm3/molecule⋅sec at 295 K (Atkinson, 1991). Cox et al. (1980) reported a rate constant of 6.2 x 10-11 cm3/molecule⋅sec for the reaction of gaseous cyclohexene with OH radicals based on a value of 8 x 10-12 cm3/molecule⋅sec for the reaction of ethylene with OH radicals. Chemical/Physical. Gaseous products formed from the reaction of cyclohexene with ozone were (% yield): formic acid (12), carbon monoxide (18), carbon dioxide (42), ethylene (1), and valeraldehyde (17) (Hatakeyama et al., 1987). In a smog chamber experiment conducted in the dark at 25 °C, cyclohexane reacted with ozone. The following products and their respective molar yields were: oxalic acid (6.16%), malonic acid (6.88%), succinic acid (0.63%), glutaric acid (5.89%), adipic acid (2.20%), 4-hydroxybutanal (2.60%), hydroxypentanoic acid (1.02%), hydroxyglutaric acid (2.33%), hydroxyadipic acid (1.19%), 4-oxobutanoic acid (6.90%), 4oxopentanoic acid (4.52%), 6-oxohexanoic acid (4.16%), 1,4-butandial (0.53%), 1,5-pentanedial (0.44%), 1,6-hexanedial (1.64%), and pentanal (17.05%). Grosjean et al. (1996) investigated the atmospheric chemistry of cyclohexene with ozone and an ozone-nitrogen oxide mixture under ambient conditions. The reaction of cyclohexene and ozone in the dark yielded pentanal and cyclohexanone. The sunlight irradiation of cyclohexene with ozonenitrogen oxide yielded the following carbonyls: formaldehyde, acetaldehyde, acetone, propanal, butanal, pentanal, and a C4 carbonyl. Cyclohexene reacts with chlorine dioxide in water forming 2-cyclohexen-1-one (Rav-Acha et al., 1987). Exposure limits: NIOSH REL: TWA 300 ppm (1,015 mg/m3), IDLH 2,000 ppm; OSHA PEL: TWA 300 ppm; ACGIH TLV: TWA 300 ppm (adopted).