ABSTRACT
HS CH3 Note: According to Chevron Phillips Company (1995) product literature, 99-99.7% ethyl mercaptan contains isopropyl mercaptans (0.1 wt %) and trace amounts of n-propyl mercaptan and tert-butyl mercaptan as impurities. CASRN: 75-08-1; DOT: 2363; DOT label: Flammable liquid; molecular formula: C2H6S; FW: 62.13; RTECS: KI9625000; Merck Index: 12, 3771 Physical state, color, and odor: Colorless liquid with a strong, disagreeable, skunk-like or rotten egg odor. Extremely flammable liquid or gas. An experimentally determined odor threshold concentration of 1 ppbv was reported by Leonardos et al. (1969). Katz and Talbert (1930) reported experimental detection odor threshold concentrations in the range 0.66-7.6 µg/m3 (0.26 to 3.0 ppbv). Melting point (°C): -144.4 (Weast, 1986) Boiling point (°C): 35 (Weast, 1986) Density (g/cm3): 0.8391 at 20 °C (Weast, 1986) 0.83147 at 25 °C (Windholz et al., 1983) Diffusivity in water (x 10-5 cm2/sec): 1.05 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: 10.50 at 20 °C (Danehy and Noel, 1960) 10.61 at 25 °C (quoted, Danehy and Parameswaran, 1968) Flash point (°C): -48.7 (NIOSH, 1997) Lower explosive limit (%): 2.8 (NIOSH, 1997) Upper explosive limit (%): 18.0 (NIOSH, 1997) Heat of fusion (kcal/mol): 1.189 (Dean, 1987) Henry’s law constant (x 10-3 atm⋅m3/mol): 3.57 at 25 °C (Przyjazny et al., 1983)
26.12 (Harkins et al., 1920) Ionization potential (eV): 9.285 ± 0.005 (Franklin et al., 1969) Soil organic carbon/water partition coefficient, log Koc: Unavailable because experimental methods for estimation of this parameter for mercaptans are lacking in the documented literature. However, its high solubility in water suggests its adsorption to soil will be nominal (Lyman et al., 1982). Octanol/water partition coefficient, log Kow: 1.49 using method of Hansch et al. (1968) Solubility in organics: Soluble in acetone, alcohol, and ether (Weast, 1986) Solubility in water: 6.76 g/L at 20 °C (quoted, Windholz et al., 1983) Vapor density: 2.54 g/L at 25 °C, 2.14 (air = 1) Vapor pressure (mmHg): 440 at 20 °C, 640 at 30 °C (quoted, Verschueren, 1983) 527.2 at 25 °C (Wilhoit and Zwolinski, 1971) Environmental fate: Biological. Ethyl mercaptan did not degrade in anaerobic sediments and sludges nor in anaerobic freshwater conditions (van Leerdam et al., 2006). Photolytic. A second-order rate constant of 1.21 x 10-12 cm3/molecule⋅sec was reported for the reaction of ethyl mercaptan and NO3 radicals in the atmosphere at 297 K (Atkinson, 1991). Chemical/Physical. In the presence of nitric oxide, ethyl mercaptan reacted with OH radicals forming ethyl thionitrite. The rate constant for this reaction is 2.7 x 10-11 at 20 °C (MacLeod et al., 1984). Exposure limits: NIOSH REL: 15-min ceiling 0.5 ppm (1.3 mg/m3), IDLH 500 ppm; OSHA PEL: ceiling 10 ppm (25 mg/m3); ACGIH TLV: TWA 0.5 ppm (adopted). Symptoms of exposure: May produce irritation of the nose and throat, headache, and fatigue (Patnaik, 1992) Toxicity: Acute oral LD50 for rats 682 mg/kg (quoted, RTECS, 1985). Uses: Odorant for natural gas; manufacturing of plastics, antioxidants, pesticides; adhesive stabilizer; chemical intermediate.
