ACETONITRILE

CASRN: 75-05-8; DOT: 1648; DOT label: Flammable liquid and poison; molecular formula: C2H3N; FW: 41.05; RTECS: AL7700000; Merck Index: 12, 68 Physical state, color, and odor: Colorless liquid with an ether-like or pungent odor of vinegar. A detection odor threshold concentration of 1,950 mg/m3 (1,161 ppmv) was experimentally determined by Dravnieks (1974). An odor threshold concentration of 13 ppmv was reported by Nagata and Takeuchi (1990). Melting point (°C): -41.0 (Stull, 1947) -45.7 (Weast, 1986) Boiling point (°C): 81.5 (Nagata and Tamura, 1996a) Density (g/cm3): 0.7820 at 20.00 °C, 0.7712 at 30.00 °C, 0.7603 at 40.00 °C, 0.7492 at 50.00 °C (Ku and Tu, 1998) 0.77662 at 25.00 °C (Nagata and Tamura, 1996a) 0.77669 at 25.00 °C (Lu et al., 2001) Diffusivity in water (x 10-5 cm2/sec): 1.23 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: 29.1 (quoted, Riddick et al., 1986) Flash point (°C): 5.6 (open cup, NIOSH, 1997) 12.8 (Windholz et al., 1983) Lower explosive limit (%): 3.0 (NFPA, 1984) Upper explosive limit (%): 16 (NIOSH, 1994) Heat of fusion (kcal/mol): 1.952 (quoted, Riddick et al., 1986) Henry’s law constant (x 10-5 atm⋅m3/mol): 2.04 at 25 °C (Snider and Dawson, 1985) 2.02 at 25 °C (static headspace-GC, Bebahani et al., 2002) 1.85 at 25 °C (Hamm et al., 1984) 1.89 at 25 °C (Benkelberg et al., 1995) 2.93 at 25 °C (static headspace-GC, Welke et al., 1998)

al., 2002)

7.30 at 5 °C, 8.90 at 10 °C, 11.6 at 15 °C, 14.6 at 20 °C, 17.6 at 25 °C (headspace-GC, Ji and Evans, 2007)

Ionization potential (eV): 12.20 ± 0.01 (Lias, 1998) Soil organic carbon/water partition coefficient, log Koc: Although experimental methods for estimation of this parameter for nitriles are lacking in the documented literature, an estimated value of -0.714 was reported by Ellington et al. (1993). Its miscibility in water and low Koc, and Kow values suggest that acetonitrile adsorption to soil will be nominal (Lyman et al., 1982). Octanol/water partition coefficient, log Kow: -0.34 (shake flask-GLC, Hansch and Anderson, 1967) -0.54 at room temperature (shake flask-GLC, Tanii and Hashimoto, 1984) Solubility in organics: Miscible with acetamide solutions, acetone, carbon tetrachloride, chloroform, 1,2-dichloroethane, ether, ethyl acetate, methanol, methyl acetate, and many unsaturated hydrocarbons (Windholz et al., 1983). Immiscible with many saturated hydrocarbons (quoted, Keith and Walters, 1992). Solubility in water: Miscible (quoted, Riddick et al., 1986). A saturated solution in equilibrium with its own vapor had a concentration of 139.1 g/L at 25 °C (Kamlet et al., 1987). Vapor density: 1.68 g/L at 25 °C, 1.42 (air = 1) Vapor pressure (mmHg): 73 at 20 °C (NIOSH, 1994) 88.8 at 25 °C (Banerjee et al., 1990) 87.02 at 25.00 °C (GC, Hussam and Carr, 1985) 86.6 at 25 °C (Hoy, 1970) 100 at 27.0 °C (Stull, 1947) 112.10 at 30 °C, 172.09 at 40 °C, 256.75 at 50 °C, 372.61 at 60 °C (equilibrium cell, Van Ness

and Kochar, 1967) 171.2 at 40 °C, 721.8 at 80 °C (Wilding et al., 2002a) 306.3 at 55.00 °C (Nagata and Tamura, 1996a) 984 at 90.00 °C (Harris et al., 2003) Environmental fate: Biological. Resting cell suspensions of the soil methylotroph Methylosinus trichosporium OB3b rapidly metabolized acetonitrile via oxygen insertion into the C-H bond generating the intermediate formaldehyde cyanohydrin. The latter compound loses hydrogen cyanide yielding formaldehyde which is then oxidized to formate (HCO2H) and bicarbonate ion (Castro et al., 1996). Photolytic. A rate constant of 4.94 x 10-14 cm3/molecule⋅sec at 24 °C was reported for the vaporphase reaction of acetonitrile and OH radicals in air (Harris et al., 1981). Reported rate constants for the reaction of acetonitrile and OH radicals in the atmosphere and in water are 1.90 x 10-14 and

acetonitrile in the atmosphere is estimated to range from 6 to 17 months (Arijs and Brasseur, 1986). Chemical/Physical. The estimated hydrolysis half-life of acetonitrile at 25 °C and pH 7 is >150,000 yr (Ellington et al., 1988). No measurable hydrolysis was observed at 85 °C at pH values 3.26 and 6.99. At 66.0 °C (pH 10.42) and 85.5 °C (pH 10.13), the hydrolysis half-lives based on first-order rate constants were 32.2 and 5.5 d, respectively (Ellington et al., 1987). The presence of hydroxide or hydronium ions facilitates hydrolysis transforming acetonitrile to the intermediate acetamide which undergoes hydrolysis forming acetic acid and ammonia (Kollig, 1993). Acetic acid and ammonia formed react quickly forming ammonium acetate. At an influent concentration of 1,000 mg/L, treatment with GAC resulted in an effluent concentration of 28 mg/L. The adsorbability of the carbon used was 194 mg/g carbon (Guisti et al., 1974). Burns with a luminous flame (Windholz et al., 1983), releasing toxic fumes of hydrogen cyanide. Exposure limits: NIOSH REL: TWA 20 ppm (34 mg/m3), IDLH 500 ppm; OSHA PEL: TWA 40 ppm (70 mg/m3); ACGIH TLV: TWA 40 ppm, STEL 60 ppm. Symptoms of exposure: Inhalation may cause nausea, vomiting, asphyxia, and tightness of the chest. Symptoms of ingestion may include gastrointestinal pain, vomiting, nausea, stupor, convulsions, and weakness (Patnaik, 1992). An irritation concentration of 875.00 mg/m3 in air was reported by Ruth (1986). Toxicity: EC50 (24-h), EC50 (48-h), LC50 (24-h), and LC50 (48-h) values for Spirostomum ambiguum were 7.35, 6.32, 17.2, and 15.2 g/L, respectively (Nałecz-Jawecki and Sawicki, 1999). LC50 (inhalation) for cats 18 gm/cm3, guinea pigs 5,655 ppm/4-h, mice 2,693 ppm/1 h, rabbits 2,828 ppm/4-h (quoted, RTECS, 1985). Acute oral LD50 in guinea pigs 177 mg/kg, rats 2,730 mg/kg, mice 269 mg/kg (quoted, RTECS, 1985). Uses: Preparation of acetamidine, acetophenone, α-naphthaleneacetic acid, thiamine; dyeing and coating textiles; extracting fish liver oils, fatty acids, and other animal and vegetable oils; recrystallizing steroids; solvent for polymers, spinning fibers, casting and molding plastics; manufacture of pharmaceuticals; chemical intermediate for pesticide manufacture; catalyst.