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TOLUENE, or METHYLBENZENE

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Originally appearing in Volume V26, Page 1063 of the 1911 Encyclopedia Britannica.
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TOLUENE, or METHYLBENZENE ,C7H5or See also:C6H5•See also:CH5, an aromatic See also:hydrocarbon; the first homologue of See also:benzene. Discovered by Pelletier (See also:Ann. shim. plays., 1838, 67, p. 269) in the oil obtained in the manufacture of See also:gas from the See also:resin of Pinus maritima, and named retinnaphte, it was prepared from the same gas by Couerbe (ibid., 69, p. 184) and named heptacarbure quadrihydrique, C7H4 (C = 6); Sainte-Claire Deville (ibid. 1841 [3] 3, p. 168) obtained it by distilling Tolu See also:balsam, naming it benzoene, and Glenard and Bouldault obtained a substance by the dry See also:distillation of See also:dragon's See also:blood which they called dracyl. The See also:complete identity of these substances was established by A. W. See also:Hofmann and See also:Muspratt, and they adopted the name toluol (anglicized to toluene), which was proposed by See also:Berzelius. Its derivatives and its relation to benzene had been previously studied by the above and other experimenters, its relation to benzene being first proved experimentally by See also:Cannizzaro and its constitution settled by See also:Fittig and Tollens's See also:synthesis from See also:sodium and a mixture of methyl iodide and brombenzene. The hydrocarbon occurs in See also:wood-See also:tar and in See also:petroleum, and is prepared commercially by fractional distillation of the See also:light oil fraction of the See also:coal-tar distillate (see COAL TAR). It may be obtained synthetically by Fittig and Tollens's method (above) ; by See also:Friedel and See also:Craft's See also:process, devised in 1897, of acting with See also:aluminium chloride on a mixture of benzene and methyl chloride; this reaction leads to the See also:production of higher homologues which may, however, break down under the continued See also:action of the aluminium chloride; or by See also:heating the toluene carboxylic acids obtained by oxidizing the higher homologues of benzene.

It forms a colourless See also:

mobile liquid, boiling at 110.3° C. and having a specific gravity of 0.8708 (13.1/4°). It is insoluble in See also:water, but dissolves readily in See also:alcohol and See also:ether. On reduction it yields hexahydrotoluene; oxidation with dilute nitric See also:acid or chromic acid gives benzoic acid; whilst chromyl chloride and water give See also:benzaldehyde. On nitration it gives ortho- and See also:para-nitrotoluenes—which on reduction yield the valuable toluidines, See also:C6H4(See also:CH3)(See also:NH2)—and on sulphonation the parasulphonic acid is formed with a little of the ortho acid. Chlorination in the See also:cold gives ortho- and para-chlortoluenes, but at the boiling point the See also:side See also:chain is substituted (see BENZALDEHYDE).

End of Article: TOLUENE, or METHYLBENZENE

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