AskDefine | Define nitrobenzene

Dictionary Definition

nitrobenzene n : a poisonous oily water-soluble liquid used as a solvent and in the manufacture of aniline

User Contributed Dictionary

English

Noun

nitrobenzene
  1. a poisonous, pale yellow oily liquid with an odour of almonds; used in the synthesis of aniline, and in the manufacture of polishes, paint etc
  2. the simplest aromatic nitro compound, C6H5NO2, prepared by reacting benzene with a mixture of nitric and sulphuric acids

Extensive Definition

Nitrobenzene, also known as nitrobenzol or oil of mirbane, is an organic compound with the chemical formula C6H5NO2. This oily water-insoluble liquid, which is quite toxic, is mainly produced as a precursor to aniline. In the laboratory it finds occasional use as a solvent, especially for electrophilic reagents.

Uses

Approximately 95% of nitrobenzene is consumed in the production of aniline.

Specialized applications

More specialized applications include the use of nitrobenzene as a precursor to rubber chemicals, pesticides, dyes, and pharmaceuticals. Nitrobenzene is also used in shoe and floor polishes, leather dressings, paint solvents, and other materials to mask unpleasant odors. Redistilled, as oil of mirbane, nitrobenzene has been used as an inexpensive perfume for soaps. A significant merchant market for nitrobenzene is its use in the production of the analgesic paracetamol (also known as acetaminophen) (Mannsville 1991). Nitrobenzene is also used in Kerr cells, as it has an unusually large Kerr constant.

Organic reactions

Aside from its conversion to aniline, nitrobenzene is readily converted to related derivatives such as azobenzene, nitrosobenzene, and phenylhydroxylamine. Substitution reactions with nitrobenzene characteristically form meta-derivatives (Mannsville 1991; Sittig 1991).

Production

Nitrobenzene is prepared by nitration of benzene with a mixture of concentrated sulfuric acid, water, and nitric acid, called "mixed acid." Its production is one of the more dangerous processes conducted in the chemical industry due to the exothermicity of the reaction (ΔH = −117 kJ/mol).
There were four producers of nitrobenzene in the United States in 1991: First Chemicals Corporation, Mobay, DuPont Chemicals, and Rubicon Inc. World capacity for nitrobenzene in 1985 was ca. 1.7×106 tonnes.

Mechanism of nitration

The reaction pathway entails formation of an adduct between the Lewis acidic nitronium ion, NO2+, and benzene. The nitronium ion is generated in situ via the reaction of nitric acid and an acidic dehydration agent, typically sulfuric acid:
HNO3 + H+ NO2+ + H2O

Safety

Nitrobenzene is highly toxic (TLV 5 mg/m3) and readily absorbed through the skin.

References

nitrobenzene in Czech: Nitrobenzen
nitrobenzene in German: Nitrobenzol
nitrobenzene in Spanish: Nitrobenceno
nitrobenzene in French: Nitrobenzène
nitrobenzene in Italian: Nitrobenzene
nitrobenzene in Latvian: Nitrobenzols
nitrobenzene in Dutch: Nitrobenzeen
nitrobenzene in Japanese: ニトロベンゼン
nitrobenzene in Polish: Nitrobenzen
nitrobenzene in Portuguese: Nitrobenzeno
nitrobenzene in Russian: Нитробензол
nitrobenzene in Slovak: Nitrobenzén
nitrobenzene in Finnish: Nitrobentseeni
nitrobenzene in Chinese: 硝基苯
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