Nitrobenzene

nitrobenzene, C₆H₅NO₂, very poisonous, flammable, pale yellow, liquid aromatic compound with an odor like that of bitter almonds. It is sometimes called oil of mirbane or nitrobenzol. Nitrobenzene melts at 5.85°C;, boils at 210.9°C;, is only slightly soluble in water, but is very soluble in ethanol, ether, and benzene. It is prepared by treating benzene with a mixture of nitric and sulfuric acids; in the resulting nitration reaction, one hydrogen in the benzene molecule is replaced with a nitro group, NO₂. The major use of nitrobenzene is in the production of aniline, commercially the most important amine; nitrobenzene is heated with iron and dilute hydrochloric acid, and the resulting anilinium chloride is treated with sodium carbonate to release aniline. In the pharmaceutical industry nitrobenzene is used in the production of the analgesic acetaminophen, or paracetamol. Nitrobenzene is also used in shoe and floor polishes, leather dressings, and paint solvents to mask unpleasant odors. As oil of mirbane, nitrobenzene was used as an inexpensive perfume for soaps and cosmetics but is now considered too toxic for such applications.

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nitrobenzene [¦nī·trō′ben‚zēn]

(organic chemistry)

C₆H₅NO₂Greenish crystals or a yellowish liquid, melting point 5.70°C; a toxic material; used in aniline manufacture. Also known as oil of mirbane.

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Nitrobenzene 

C₆H₅NO₂, the simplest aromatic nitro compound; an oily light yellow liquid. Melting point, 5.7°C; boiling point, 210.9°C; density, 1.987 g/cm³ at 25°C. It is poorly soluble in water but mixes well with organic solvents.

Upon reduction, nitrobenzene is converted to aniline or hydrazobenzene, depending on the conditions. Under the action of acids, hydrazobenzene isomerizes to benzidine. Nitration, sulfonation, and chlorination of nitrobenzene take place mainly at the meta- position to the nitro group, for example:

Nitrobenzene is produced by nitration of benzene by a nitrating mixture. It is poisonous, with a maximum permissible concentration in air of 3 mg/m³ in work areas and 0.008 mg/m³ in residential buildings.

Nitrobenzene is mainly used in the production of aniline. In small quantities, nitrobenzene is also used in the production of intermediates for dyes (methanilic acid and benzidine), and also certain dyes (for example, induline).

REFERENCE

Orlova, E. Iu. Khimiia i tekhnologiia brizantnykh vzryvchatykh ve-shchestv. Leningrad, 1973.