ABSTRACT
CH3H3C CASRN: 108-67-8; DOT: 2325; DOT label: Combustible liquid; molecular formula: C9H12; FW: 120.19; RTECS: OX6825000; Merck Index: 12, 5967 Physical state, color, and odor: Colorless liquid with a peculiar odor. An odor threshold concentration of 170 ppbv was reported by Nagata and Takeuchi (1990). Melting point (°C): -44.7 (Weast, 1986) -52.7 (quoted, Verschueren, 1983) Boiling point (°C): 164.5-164.6 °C (Rintelen et al., 1937) Density (g/cm3): 0.8652 at 20 °C (Weast, 1986) 0.86104 at 25.00 °C, 0.84873 at 30.00 °C (Deng et al., 2006) 0.86110 at 25.00 °C, 0.84880 at 40.00 °C (Comelli et al., 1996) Diffusivity in water (x 10-5 cm2/sec): 0.73 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: >14 (Schwarzenbach et al., 1993) Flash point (°C): 44 (Dean, 1987) 50 (NFPA, 1984) Heat of fusion (kcal/mol): 1.892-2.274 (Dean, 1987) Henry’s law constant (x 10-3 atm⋅m3/mol): 5.00 at 22 °C (dynamic stripping cell-MS, Karl et al., 2003) 4.741 at 22 °C (SPME-GC, Saraullo et al., 1997) 4.03, 4.60, 5.71, 6.73, and 9.63 at 10, 15, 20, 25, and 30 °C, respectively (EPICS, Ashworth et al.,
1988) Interfacial tension with water (dyn/cm at 20 °C): 38.70 (Demond and Lindner, 1993) Ionization potential (eV): 8.40 (Lias, 1998)
oc 2.82 (Schwarzenbach and Westall, 1981) Octanol/water partition coefficient, log Kow: 3.41 (Campbell and Luthy, 1985) 3.42 (shake flask-GC, Chiou et al., 1982; Hansch and Leo, 1979) 3.78 (Hammers et al., 1978) 3.88 (average of four values, generator column-HPLC, Garst, 1984) Solubility in organics: Miscible with alcohol, benzene, ether (Windholz et al., 1983), and trimethylbenzene isomers. Solubility in water: 48.2 mg/L at 25.0 °C (shake flask-GC, Sutton and Calder, 1975) 640 µmol/L at 25.0 °C (shake flask-UV spectrophotometry, Andrews and Keefer, 1950a) 97.7 mg/L at 25 °C (shake flask-GC, Chiou et al., 1982) 282 µmol/L in 0.5 M NaCl at 25 °C (Wasik et al., 1984) 383, 415, 455, and 485 µmol/L at 15.0, 25.0, 35.0, and 45.0 °C, respectively (Sanemasa et al.,
1982) <200 mg/L at 25 °C (residue-volume method, Booth and Everson, 1948) In mg/kg: 107 at 10 °C, 109 at 20 °C, 112 at 30 °C (shake flask-GC, Howe et al., 1987) 328 µmol/kg at 25.0 °C (shake flask-UV spectrophotometry, Vesala, 1974) 8.55 x 10-6 at 25 °C (mole fraction, inert gas stripping-GC, Li et al., 1993) Vapor density: 4.91 g/L at 25 °C, 4.15 (air = 1) Vapor pressure (mmHg): 0.6 at 10 °C, 3.8 at 30 °C, 11.5 at 30 °C (Rintelen et al., 1937) 0.44 at 0 °C, 0.93 at 10 °C, 1.86 at 20 °C, 3.51 at 30 °C, 6.33 at 40 °C, 11.0 at 50 °C, 18.3 at 60 °C, 29.5 at 70 °C, 46.0 at 80 °C, 69.9 at 90 °C, 103.4 at 100 °C (cathetometry, Kassel, 1936)
2.42 at 25 °C (quoted, Mackay et al., 1982) Environmental fate: Biological. In anoxic groundwater near Bemidji, MI, 1,3,5-trimethylbenzene anaerobically biodegraded to the intermediate tentatively identified as 3,5-dimethylbenzoic acid (Cozzarelli et al., 1990). Photolytic. Glyoxal, methylglyoxal, and biacetyl were produced from the photooxidation of 1,3,5-trimethylbenzene by OH radicals in air at 25 °C (Tuazon et al., 1986a). The rate constant for the reaction of 1,3,5-trimethylbenzene and OH radicals at room temperature was 4.72 x 10-11 cm3/molecule⋅sec (Hansen et al., 1975). A rate constant of 2.97 x 10-8 L/molecule⋅sec was reported for the reaction of 1,3,5-trimethylbenzene with OH radicals in the gas phase (Darnall et al., 1976). Similarly, a room temperature rate constant of 6.05 x 10-11 cm3/molecule⋅sec was reported for the vapor-phase reaction of 1,3,5-trimethylbenzene with OH radicals (Atkinson, 1985). At 25 °C, a rate constant of 3.87 x 10-11 cm3/molecule⋅sec was reported for the same reaction (Ohta and Ohyama, 1985). Chemical/Physical. 1,3,5-Trimethylbenzene will not hydrolyze because it does not contain a hydrolyzable functional group (Kollig, 1993). Exposure limits: NIOSH REL: TWA 25 ppm (125 mg/m3); ACGIH TLV: TWA for mixed isomers 25 ppm (adopted).
