ABSTRACT
CH3 CASRN: 526-73-8; DOT: 2325; DOT label: Combustible liquid; molecular formula: C9H12; FW: 120.19; RTECS: DC3300000 Physical state, color, and odor: Clear, colorless, flammable liquid with an aromatic odor similar to propylbenzene, ethylbenzenes, or xylenes. Melting point (°C): -25.4 (Weast, 1986) Boiling point (°C): 176.1 (Weast, 1986) Density (g/cm3): 0.8944 at 20 °C (Weast, 1986) Diffusivity in water (x 10-5 cm2/sec): 0.74 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: >14 (Schwarzenbach et al., 1993) Flash point (°C): 48 (Dean, 1987) 53 (90.5% solution, NFPA, 1984) Lower explosive limit (%): 0.8 (NIOSH, 1997) Upper explosive limit (%): 6.6 (NIOSH, 1997) Heat of fusion (kcal/mol): 1.955 (Dean, 1987) Henry’s law constant (x 10-3 atm⋅m3/mol): 3.18 at 25 °C (approximate - calculated from water solubility and vapor pressure) Ionization potential (eV): 8.42 (Lias, 1998) Soil organic carbon/water partition coefficient, log Koc: 2.80 (Schwarzenbach and Westall, 1981)
ow 3.55 (generator column-HPLC/GC: Wasik et al., 1981, Tewari et al., 1982, Doucette and Andren,
1988) 3.66 (Camilleri et al., 1988; estimated from HPLC capacity factors, Hammers et al., 1982) Solubility in organics: Soluble in acetone, alcohol, benzene, and ether (Weast, 1986) Solubility in water: 75.2 mg/L at 25.0 °C; 48.6 mg/L in artificial seawater (salinity = 34.5 g/kg) at 25.0 °C (shake
flask-GC, Sutton and Calder, 1975) 545 µmol/L at 25.0 °C (generator column-HPLC, Tewari et al., 1982; generator column-
HPLC/GC, Wasik et al., 1981) 498, 520, 597, and 702 µmol/L at 15.0, 25.0, 35.0, and 45.0 °C, respectively (Sanemasa et al.,
1982) Vapor density: 4.91 g/L at 25 °C, 4.15 (air = 1) Vapor pressure (mmHg): 1.51 at 25 °C (quoted, Mackay et al., 1982) Environmental fate: Photolytic. Glyoxal, methylglyoxal, and biacetyl were produced from the photooxidation of 1,2,3-trimethylbenzene by OH radicals in air at 25 °C (Tuazon et al., 1986a). The rate constant for the reaction of 1,2,3-trimethylbenzene and OH radicals at room temperature was 1.53 x 10-11 cm3/molecule⋅sec (Hansen et al., 1975). A rate constant of 1.49 x 10-8 L/molecule⋅sec was reported for the reaction of 1,2,3-trimethylbenzene with OH radicals in the gas phase (Darnall et al., 1976). Similarly, a room temperature rate constant of 3.16 x 10-11 cm3/molecule⋅sec was reported for the vapor-phase reaction of 1,2,3-trimethylbenzene with OH radicals (Atkinson, 1985). At 25 °C, a rate constant of 2.69 x 10-11 cm3/molecule⋅sec was reported for the same reaction (Ohta and Ohyama, 1985). 2,3-Butanedione was the only products identified from the OH radical-initiated reaction of 1,2,4-trimethylbenzene in the presence of nitrogen dioxide. The amount of 2,3butanedione formed decreased with increased concentration of nitrogen dioxide (Bethel et al., 2000). Chemical/Physical. 1,2,3-Trimethylbenzene will not hydrolyze because it does not contain a hydrolyzable group (Kollig, 1993). Exposure limits: NIOSH REL: TWA 25 ppm (125 mg/m3); ACGIH TLV: TWA for mixed isomers 25 ppm (adopted). Symptoms of exposure: Skin, eye, and respiratory irritant. Source: Detected in distilled water-soluble fractions of 87 octane gasoline (0.30 mg/L), 94 octane gasoline (0.81 mg/L), Gasohol (0.80 mg/L), No. 2 fuel oil (0.22 mg/L), diesel fuel (0.09 mg/L), and military jet fuel JP-4 (0.19 mg/L) (Potter, 1996). Thomas and Delfino (1991) equilibrated contaminant-free groundwater collected from Gainesville, FL with individual fractions of three individual petroleum products at 24-25 °C for 24 h. The aqueous phase was analyzed for organic compounds via U.S. EPA approved test method 602. Average 1,2,3-trimethylbenzene concentrations detected in water-soluble fractions of unleaded gasoline, kerosene, and diesel fuel were 1.219, 0.405, and 0.118 mg/L, respectively.
