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| Names | |||
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| Preferred IUPAC name Nitrobenzene | |||
| Other names Nitrobenzol Nitritebenzene Oil of mirbane | |||
| Identifiers | |||
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3D model (JSmol) | |||
| 507540 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.002.469 | ||
| EC Number |
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| 50357 | |||
| KEGG |
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| RTECS number |
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| UNII | |||
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| Properties | |||
| C6H5NO2 | |||
| Molar mass | 123.11 g/mol | ||
| Appearance | yellowish, oily liquid[1] | ||
| Odor | pungent, like paste shoe polish[1] to almond-like | ||
| Density | 1.199 g/cm3 | ||
| Melting point | 5.7 °C (42.3 °F; 278.8 K) | ||
| Boiling point | 210.9 °C (411.6 °F; 484.0 K) | ||
| 0.19 g/100 ml at 20 °C | |||
| Vapor pressure | 0.3 mmHg (25°C)[1] | ||
| −61.80·10−6 cm3/mol | |||
Refractive index (nD) | 1.5215 | ||
| Viscosity | 1.8112 mPa·s[2] | ||
| Hazards | |||
| GHS labelling: | |||
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| Danger | |||
| H301,H311,H331,H351,H360,H372,H412 | |||
| P201,P202,P260,P264,P270,P271,P273,P280,P281,P301+P310,P302+P352,P304+P340,P308+P313,P311,P312,P314,P321,P322,P330,P361,P363,P403+P233,P405,P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | 88 °C (190 °F; 361 K) | ||
| 480 °C (896 °F; 753 K) | |||
| Explosive limits | 1.8%-?[1] | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) | 780 mg/kg (rat, oral) 600 mg/kg (rat, oral) 590 mg/kg (mouse, oral) [3] | ||
LDLo (lowest published) | 750 mg/kg (dog, oral)[3] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 1 ppm (5 mg/m3) [skin][1] | ||
REL (Recommended) | TWA 1 ppm (5 mg/m3) [skin][1] | ||
IDLH (Immediate danger) | 200 ppm[1] | ||
| Related compounds | |||
Related compounds | Aniline Benzenediazonium chloride Nitrosobenzene | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Nitrobenzene is anaromaticnitro compound and the simplest of thenitrobenzenes, with thechemical formulaC6H5NO2. It is a water-insoluble pale yellow oil with analmond-like odor. It freezes to give greenish-yellow crystals. It is produced on a large scale frombenzene as a precursor toaniline. In the laboratory, it is occasionally used as asolvent, especially forelectrophilicreagents. As confirmed byX-ray crystallography, nitrobenzene is a planar molecule.[4]
Nitrobenzene is prepared bynitration ofbenzene with a mixture of concentratedsulfuric acid,water, andnitric acid. This mixture is sometimes called "mixed acid."
The production of nitrobenzene is one of the most dangerous processes conducted in the chemical industry because of the exothermicity of the reaction (ΔH = −117 kJ/mol).[5]
Thenitration process involves formation of thenitronium ion (NO2+), followed by anelectrophilic aromatic substitution reaction of it with benzene. The nitronium ion is generated by the reaction of nitric acid and an acidic dehydration agent, typically sulfuric acid:
World capacity for nitrobenzene in 1985 was about 1,700,000tonnes.[5]
Approximately 95% of nitrobenzene industrially produced ishydrogenated toaniline:[5]
Aniline is a precursor tourethane polymers,rubber chemicals,pesticides,dyes (particularlyazo dyes),explosives, andpharmaceuticals.
Nitrobenzene is used to mask unpleasant odors in shoe and floor polishes, leather dressings, paintsolvents, and other materials. Redistilled, as oil of mirbane, nitrobenzene had been used as an inexpensive perfume forsoaps. It has been replaced by less toxic chemicals for this purpose.[6] A significant merchant market for nitrobenzene is its use in the production of theanalgesicparacetamol (also known as acetaminophen).[7] Nitrobenzene is also used inKerr cells, as it has an unusually largeKerr constant. Evidence suggests its use in agriculture as a plant growth/flowering stimulant.[8]
Aside from its conversion to aniline, nitrobenzene can be selectively reduced toazoxybenzene,[9]azobenzene,[10]nitrosobenzene,[11]hydrazobenzene,[12] andphenylhydroxylamine.[13] It has been used as a mild oxidant in reactions like theSkraup quinoline synthesis.[14]
Nitrobenzene is highly toxic (Threshold Limit Value 5 mg/m3) and readily absorbed through the skin.
Prolonged exposure may cause serious damage to the centralnervous system, impair vision, cause liver or kidney damage, anemia and lung irritation. Inhalation of vapors may induce headache, nausea, fatigue, dizziness,cyanosis, weakness in the arms and legs, and in rare cases may be fatal. The oil is readily absorbed through the skin and may increase heart rate, cause convulsions or rarely death. Ingestion may similarly cause headaches, dizziness, nausea, vomiting and gastrointestinal irritation, loss of sensation/use in limbs and also causes internal bleeding.[11]
Nitrobenzene is considered a likely human carcinogen by the United States Environmental Protection Agency,[15] and is classified by theIARC as aGroup 2B carcinogen which is "possibly carcinogenic to humans".[16] It has been shown to cause liver, kidney, and thyroid adenomas and carcinomas in rats.[17]
It is classified as anextremely hazardous substance in the United States as defined in Section 302 of the U.S.Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.[18]
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