NITROBENZENE

CASRN: 98-95-3; DOT: 1662; DOT label: Poison; molecular formula: C6H5NO2; FW: 123.11; RTECS: DA6475000; Merck Index: 12, 6685 Physical state, color, and odor: Clear, light yellow to brown, oily liquid with an almond-like or shoe polish odor. May darken on exposure to air. An experimentally determined odor threshold concentration of 4.7 ppbv was reported by Leonardos et al. (1969). A detection odor threshold concentration of 9.6 mg/m3 (1.9 ppmv) was determined by Katz and Talbert (1930). Melting point (°C): 5.7 (Weast, 1986) Boiling point (°C): 210.8 (Weast, 1986) Density (g/cm3): 1.20329 at 20.00 °C (Tsierkezos et al., 2000) 1.2125 at 10 °C, 1.205 at 18 °C, 1.1986 at 25 °C (quoted, Standen, 1967) 1.1937 at 30.00 °C (Viswanathan et al., 1996, 2000) 1.19337 at 30.00 °C (Ramadevi et al., 1996) Diffusivity in water (x 10-5 cm2/sec): 0.87 at 20 °C using method of Hayduk and Laudie (1974) Dissociation constant, pKa: >15 (Christensen et al., 1975) Flash point (°C): 88.5 (NIOSH, 1997) Lower explosive limit (%): 1.8 at 100 °C (NIOSH, 1997) Entropy of fusion (cal/mol⋅K): 9.27 (Pacor, 1967) Heat of fusion (kcal/mol): 2.58 (Pacor, 1967) Henry’s law constant (x 10-5 atm⋅m3/mol): 2.45 at 25 °C (gas stripping-UV spectrophotometry, Warner et al., 1987)

Dewulf et al., 1999)

1.78 at 24 °C (sparging chamber-UV spectrophotometry, Ngim and Crosby, 2001) 9.86 at 25 °C (thermodynamic method-GC/UV spectrophotometry, Altschuh et al., 1999) Interfacial tension with water (dyn/cm at 20 °C): 25.66 (Harkins et al., 1920) Ionization potential (eV): 9.92 (Franklin et al., 1969) Bioconcentration factor, log BCF: 2.41 (algae, Geyer et al., 1984) 1.38 (Chlorella fusca, Geyer et al., 1981) 1.60 (activated sludge), 1.30 (algae) (Freitag et al., 1985) 1.18 (28-d exposure, fathead minnow, Veith et al., 1979) 1.47 (3-d exposure, Poecilia reticulata, Deneer et al., 1987) Soil organic carbon/water partition coefficient, log Koc: 1.85 (river sediment), 1.95 (coal wastewater sediment) (Kopinke et al., 1995) 2.36 (Løkke, 1984) 1.49, 1.95, >2.01 (various Norwegian soils, Seip et al., 1986) 1.94 (Batcombe silt loam, Briggs, 1981) 2.28 (Lincoln sand, Wilson et al., 1981) 2.15 (Delta soil, Miller and Weber, 1986) 1.95 (Captina silt loam), 2.02 (McLaurin sandy loam) (Walton et al., 1992) Kd = 3.5 mL/g on a Cs+-kaolinite (Haderlein and Schwarzenbach, 1993) Octanol/water partition coefficient, log Kow: 1.85 (shake flask, Briggs, 1981, Campbell and Luthy, 1985; shake flask-UV spectrophotometry,

Fujita et al., 1964; generator column-HPLC, generator column-HPLC, Tewari et al., 1982; Walton et al., 1992; generator column-HPLC/GC, Wasik et al., 1981)

1.83 (RP-HPLC, Garst and Wilson, 1984; shake flask-GLC, de Bruijn et al., 1989; shake flaskLSC at 23 °C, Banerjee et al., 1990)

1.828 and 1.836 at 25 °C (shake flask-HPLC, Brooke et al., 1990) 1.84 (Geyer et al., 1984) 1.792 (Lu and Metcalf, 1975) 1.88 (quoted, Leo et al., 1971; dialysis-HPLC, Andersson and Schräder, 1999) 1.70 (estimated from HPLC capacity factors, Hammers et al., 1982) Solubility in organics: Soluble in acetone, ethanol, benzene, ether (Weast, 1986), and many other hydrocarbons including toluene and ethylbenzene Solubility in water: 2,060 mg/kg at 30 °C (shake flask-interferometer, Vermillion et al., 1941) 2,090 mg/L at 25 °C (shake flask-LSC, Banerjee et al., 1980) 2,043 mg/L at 25 °C (Chiou, 1985) 1,780 mg/kg at 15 °C, 2,050 mg/kg at 30 °C (shake flask-interferometer, Gross and Saylor, 1931) 1,930 mg/L solution at 25 °C (shake flask-UV spectrophotometry, Andrews and Keefer, 1950) 18.35 mM at 35 °C (Hine et al., 1963)

Wasik et al., 1981)

In g/L: 1.77 at 10.00 °C, 1.93 at 20.00 °C, 2.06 at 30 °C (shake flask-UV spectrophotometry, Beneš and Dohnal, 1999)

0.0158 mol/kg at 25 °C (shake flask-titration, Hammett and Chapman, 1934) Vapor density: 5.03 g/L at 25 °C, 4.25 (air = 1) Vapor pressure (mmHg): 0.066 at 6.09 °C, 0.111 at 12.57 °C, 0.127 at 14.67 °C, 0.133 at 14.72 °C, 0.218 at 21.37 °C, 0.220

at 21.54 °C, 0.242 at 23.14 °C (Lynch and Wilke, 1960) 0.28 at 25 °C (quoted, Warner et al., 1987) 0.600 at 35 °C (Hine et al., 1963) 21.3 at 100 °C (Sonawane and Kumar, 1998) Environmental fate: Biological. In activated sludge, 0.4% of the applied nitrobenzene mineralized to carbon dioxide after 5 d (Freitag et al., 1985). Under anaerobic conditions using a sewage inoculum, nitrobenzene degraded to aniline (Hallas and Alexander, 1983). When nitrobenzene (5 and 10 mg/L) was statically incubated in the dark at 25 °C with yeast extract and settled domestic wastewater inoculum, complete biodegradation with rapid acclimation was observed after 7 to 14 d (Tabak et al., 1981). In activated sludge inoculum, 98.0% COD removal was achieved in 5 d. The average rate of biodegradation was 14.0 mg COD/g⋅h (Pitter, 1976). Razo-Flores et al. (1999) studied the fate of nitrobenzene (50 mg/L) in an upward-flow anaerobic sludge bed reactor containing a mixture of volatile fatty acids and/or glucose as electron donors. The nitrobenzene loading rate and hydraulic retention time for this experiment were 43 mg/L⋅d and 28 h, respectively. Nitrobenzene was effectively reduced (>99.9%) to aniline (92% molar yield) in stoichiometric amounts for the 100-d experiment. Photolytic. Irradiation of nitrobenzene in the vapor phase produced nitrosobenzene and 4nitrophenol (HSDB, 1989). Titanium dioxide suspended in an aqueous solution and irradiated with UV light (λ = 365 nm) converted nitrobenzene to carbon dioxide at a significant rate (Matthews, 1986). A carbon dioxide yield of 6.7% was achieved when nitrobenzene adsorbed on silica gel was irradiated with light (λ >290 nm) for 17 h (Freitag et al., 1985). An aqueous solution containing nitrobenzene (500 µM) and hydrogen peroxide (100 µM) was irradiated with UV light (λ = 285-360 nm). After 18 h, 2% of the substrate was converted into 2-, 3-, and 4-nitrophenols having an isomer distribution of 50, 29.5, and 20.5%, respectively (Draper and Crosby, 1984). When nitrobenzene, with nitrogen as a carrier gas, was passed through a quartz cell and irradiated by two 220-volt arcs, nitrosobenzene and 4-nitrophenol formed as the major products (Hastings and Matsen, 1948). A rate constant of 1.4 x 10-13 cm3/molecule⋅sec was reported for the gas-phase reaction of nitrobenzene and OH radicals in air (Witte et al., 1986). Chemical/Physical. In an aqueous solution, nitrobenzene (100 µM) reacted with Fenton’s reagent (35 µM). After 15 min, 2-, 3-, and 4-nitrophenol were identified as products. After 6 h, about 50% of the nitrobenzene was destroyed. The pH of the solution decreased due to the formation of nitric acid (Lipczynska-Kochany, 1991). Augusti et al. (1998) conducted kinetic studies for the reaction of nitrobenzene (0.2 mM) and other monocyclic aromatics with Fenton’s reagent (8 mM hydrogen peroxide; [Fe+2] = 0.1 mM) at 25 °C. They reported a reaction rate constant of 0.0260/min. Under anaerobic conditions, nitrobenzene in distilled water was reduced in the presence of iron metal (33.3 g/L acid washed 18 to 20 mesh). Aniline formed with nitrosobenzene as an

pseudo-first-order disappearance rate of 0.035/min, the half-life was 19.7 min (Agrawal and Tratnyek, 1996). Yu and Bailey (1992) studied the reaction of nitrobenzene with four sulfide minerals under anaerobic conditions. Observed half-lives of nitrobenzene were 7.5, 40, 105, and 360 h for the reaction with sodium sulfide, alabandite (manganese sulfide), sphalerite (zinc sulfide), and molybdenite (molybdenum sulfide), respectively. Aniline and elemental sulfur were found as reduction products of nitrobenzene-manganese sulfide reaction. Aniline was also a reduction product in the nitrobenzene-molybdenum sulfide and nitrobenzene-sodium sulfide reactions. Several unidentified products formed in the reaction of nitrobenzene and sphalerite (Yu and Bailey, 1992). At an influent concentration of 1,023 mg/L, treatment with GAC resulted in an effluent concentration of 44 mg/L. The adsorbability of the carbon used was 196 mg/g carbon (Guisti et al., 1974). Similarly, at influent concentrations of 10, 1.0, 0.1, and 0.01 mg/L, the GAC adsorption capacities were 180, 68, 25, and 9.3 mg/g, respectively (Dobbs and Cohen, 1980). Nitrobenzene will not hydrolyze in water because it does not contain a hydrolyzable functional group (Kollig, 1993). Exposure limits: NIOSH REL: TWA 1 ppm (5 mg/m3), IDLH 200 ppm; OSHA PEL: TWA 1 ppm; ACGIH TLV: TWA 1 ppm (adopted). Symptoms of exposure: Chronic exposure may cause anemia. Acute effects include headache, dizziness, nausea, vomiting, dyspnea (Patnaik, 1992), drowsiness, methemoglobinemia with cyanosis (Windholz et al., 1983). An irritation concentration of 230.00 mg/m3 in air was reported by Ruth (1986). Toxicity: EC50 (15-min) for Photobacterium phosphoreum 67.7 mg/L (Yuan and Lang, 1997). IC50 (24-h) for river bacteria 79.5 mg/L (Yuan and Lang, 1997). LC50 (contact) for earthworm (Eisenia fetida) 16 µg/cm2 (Neuhauser et al., 1985). LC50 (96-h) for bluegill sunfish 43 mg/L (Spehar et al., 1982), Cyprinodon variegatus 59 ppm using natural seawater (Heitmuller et al., 1981). LC50 (72-h) for Cyprinodon variegatus >120 ppm (Heitmuller et al., 1981). LC50 (48-h) for red killifish 275 mg/L (Yoshioka et al., 1986), Daphnia magna 27 mg/L (LeBlanc, 1980), Cyprinodon variegatus >120 ppm (Heitmuller et al., 1981). LC50 (24-h) for Daphnia magna 24 mg/L (LeBlanc, 1980), Cyprinodon variegatus >120 ppm (Heitmuller et al., 1981). Acute oral LD50 for mice 590 mg/kg, rats 489 mg/kg (Yoshioka et al., 1986). Heitmuller et al. (1981) reported a NOEC of 22 ppm. Uses: Solvent for cellulose ethers; modifying esterification of cellulose acetate; ingredient of metal polishes and shoe polishes; manufacture of aniline, benzidine, quinoline, azobenzene, drugs, photographic chemicals.