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NITROBENZENE, C6H6NO2

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Originally appearing in Volume V19, Page 713 of the 1911 Encyclopedia Britannica.
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NITROBENZENE, C6H6NO2 , the simplest aromatic nitro See also:compound. It was first isolated in 1834 by E. See also:Mitscherlich (Pogg. See also:Ann., 1834, 31, p. 625), and is prepared commercially by the See also:gradual addition of See also:benzene to a well-cooled mixture of concentrated nitric and sulphuric acids, the oily product being separated, washed with See also:alkali, and then distilled. It also results in the oxidation of See also:aniline by monopersulphuric See also:acid (H. See also:Caro, Zeit. angew. Chem., 1898, p. 845) or by See also:potassium permanganate (E. See also:Bamberger, Ber., 1893. 26, p. 496); by the oxidation of nitrosobenzene (below) with atmospheric See also:oxygen; or by the decomposition of benzene diazonium nitrate See also:mercury nitrite, Hg(NO2)2.2C6H,N2•NO3, with See also:copper See also:powder (A.

Hantzsch, Ber., 1900, 33, p. 2551). It is a yellowish liquid possessing a strong See also:

smell of oil of See also:bitter almonds. It boils at 209°C., and melts at 3.6° C. (C.E. Linebarger, Amer. Chem. Jour., 1896, 18, p. 437). The products of its electrolytic reduction vary with the conditions: in sulphuric acid See also:solution it yields See also:para-aminophenol (L. Gattermann, Ber., 1893, 26, p. 1844); in alcoholic alkaline solution it yields azoxybenzene; in acid alcoholic solution, See also:benzidine; in ammoniacal alcoholic solution, phenylhydrazine.

With See also:

chlorine, in the presence of See also:iodine or See also:antimony chloride, it yields See also:meta-chlornitrobenzene. Hydrobromic acid at 185°-19o°C. converts it into di- and tri-bromaniline. It occasionally acts as an oxidizing See also:agent, as in the,'preparation of See also:quinoline and See also:fuchsine. It is used commercially for the preparation of aniline and of benzidine; and in See also:perfumery (oil of mirbane). Dinitrobenzenes, See also:C6H4(NO2)2•—Ortho-dinitrobenzene is formed in small quantity in the preparation of meta-dinitrobenzene, and also results from the See also:action of nitro-sulphuric acid on See also:bismuth triphenyl (A. Gillmeister, Ber., 1897, 30, p. 2844). It forms colourless crystals which melt at 116.5° C. and See also:boil at 319° C. (773 mm.). On boiling with aqueous See also:caustic soda, it yields ortho-nitrophenol. Meta-dinitrobenzene is formed by the See also:direct nitration of nitrobenzene with fuming nitric acid, the product being poured into See also:water and re-crystallized from dilute See also:alcohol. It forms practically colourless needles which melt at 89.7° C., and boil at 3o2.8° C.

It is used for the preparation of meta-phenylene diamine. Para-dinitrobenzene results from the action of See also:

nitrogen peroxide on an ethereal solution of quinone dioxime (R. Oliveri-Tortorici, Gazz., 1900, 30, i.533). It crystallizes in colourless needles, which melt at 170-1720 C. It is only slightly soluble in See also:cold water and cold alcohol. Trinitrobenzenes, C6H3(NO2),.—Asymmetrical (1.2.4) trinitrobenzene results from the action of fuming nitric and sulphuric acids on para-dinitrobenzene. It forms yellow crystals, which melt at 57'5` C. When boiled with dilute aqueous caustic soda it yields 2.4 dinitrophenol. Symmetrical (1.3.5) trinitrobenzene is formed by the further nitration of meta-dinitrobenzene with fuming sulphuric and nitric acids; by the action of hydrochloric acid on See also:sodium malonyl aldehyde (H. B. See also:Hill and J. Torray, Ber., 1895, 28, 2598), or by the action of water on 2.4.6-trinitrobenzoic acid (See also:German patent 77353).

It crystallizes in prisms which melt at 121° C. It yields addition compounds with aniline and See also:

naphthalene, and combines directly with potassium methylate, sodio-malonic ester and hydrocyanic ester. Alkaline potassium ferricyanide oxidizes it to picric acid. Nitrosobenzene, C6H5NO, was first obtained by the action of nitrosyl bromide or chloride on mercury See also:diphenyl (A. See also:Baeyer, Ber., 1874, 7, p. 1638). It results, with other products, in the oxidation of phenyl diazonium chloride with alkaline potassium ferricyanide; of $-phenylhydroxylamine with chromic acid mixture (E. Bamberger, Ber., 1893, 26, pp. 473, 483, 1894, 27, p. 1349), or of aniline by monopersulphurlc acid (German patent 110575). It exists in two crystalline forms. Nitric acid passed into its See also:chloroform solution gives phenyl diazonium nitrate.

With aniline and acetic acid it yields azobenzene. It combines with aromatic See also:

amines to See also:form azocompounds, with arylhydroxylamines to form azoxy compounds, and with See also:hydroxylamine it gives isodiazobenzene.

End of Article: NITROBENZENE, C6H6NO2

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