ABSTRACT
NO2 CASRN: 100-25-4; DOT: 1597; DOT label: Poison; molecular formula: C6H4N2O4; FW: 168.11; RTECS: CZ7525000 Physical state and color: Clear, colorless to white crystalline solid or monoclinic crystals. Slowly turns yellow on exposure to air. Melting point (°C): 174.00 (Martin et al., 1979) Boiling point (°C): 299 (NIOSH, 1997) Density (g/cm3): 1.625 at 18 °C (Weast, 1986) Diffusivity in water (x 10-5 cm2/sec): 0.79 at 20 °C using method of Hayduk and Laudie (1974) Entropy of fusion (cal/mol⋅K): 15.0 (Andrews et al., 1926) Henry’s law constant (x 10-7 atm⋅m3/mol): 4.79 at 35 °C (approximate - calculated from water solubility and vapor pressure) Ionization potential (eV): 10.50 (NIOSH, 1997) Soil organic carbon/water partition coefficient, log Koc: Kd ≈ 4,000 mL/g on a Cs+-kaolinite (Haderlein and Schwarzenbach, 1993). Octanol/water partition coefficient, log Kow: 1.35 at 25 °C, 1.30 at 60 °C (shake flask-UV spectrophotometry, Kramer and Henze, 1990) Solubility in organics: Soluble in acetone, acetic acid, benzene, toluene (Weast, 1986), and alcohol (3.3 g/L) (Windholz et al., 1983) Solubility in water: 61.8 mg/L at 25 °C (Leiga and Sarmousakis, 1966) 80 mg/L in cold water, 1.8 g/L at 100 °C (quoted, Windholz et al., 1983) 0.617 mM at 35 °C (Hine et al., 1963)
2.25 x 10-4 at 35 °C (Hine et al., 1963) Environmental fate: Biological. In activated sludge inoculum, following a 20-d adaptation period, no biodegradation was observed (Pitter, 1976). Photolytic. Low et al. (1991) reported that the nitro-containing compounds (e.g., 2,4dinitrophenol) undergo degradation by UV light in the presence of titanium dioxide yielding ammonium, carbonate, and nitrate ions. By analogy, 1,4-dinitrobenzene should degrade forming identical ions. Chemical/Physical. Releases toxic nitrogen oxides when heated to decomposition (Sax and Lewis, 1987). 1,4-Dinitrobenzene will not hydrolyze in water (Kollig, 1993). Exposure limits (mg/m3): NIOSH REL: TWA 1, IDLH 50; OSHA PEL: TWA 1 ACGIH TLV: TWA 0.15 ppm for all isomers (adopted). Toxicity: EC50 (15-min) for Photobacterium phosphoreum 260 µg/L (Yuan and Lang, 1997). IC50 (24-h) for river bacteria 1.27 mg/L (Yuan and Lang, 1997). Uses: Organic synthesis; dyes.
