toluene

toluene

a colourless volatile flammable liquid with an odour resembling that of benzene, obtained from petroleum and coal tar and used as a solvent and in the manufacture of many organic chemicals. Formula: C₆H₅CH₃

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

toluene

[′täl·yə‚wēn]

(organic chemistry)

C₆H₅CH₃ A colorless, aromatic liquid derived from coal tar or from the catalytic reforming of petroleum naphthas; insoluble in water, soluble in alcohol and ether, boils at 111°C; used as a chemical intermediate, for explosives, and in high-octane gasolines. Also known as methylbenzene; phenylmethane; toluol.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Toluene

 

(or methylbenzene), a colorless, flammable liquid with an odor similar to that of benzene. Melting point, –95°C; boiling point, 110.6°C; density, 0.8669 g/cm³ at 20°C.

Toluene forms explosive mixtures with air in proportions of 1.27–7.0 percent by volume. Its ignition temperature is 552°C, and its flash point is 4.4°C. Toluene is miscible with most organic solvents; at 22°C, 0.492 g of toluene dissolves in 1 kg of water, and 0.526 g of water dissolves in 1 kg of toluene.

Toluene is a component of certain petroleums. In industry, it is isolated mainly from coal tars and the products of the thermal conversion of petroleum fractions. Toluene is an important chemical raw material. It is characterized by reactions of electro-philic substitution in the aromatic ring and transformations of the methyl group, with retention of the ring. Electrophilic substitution occurs more readily than in benzene and is directed mainly at the para (4-) and ortho (2,6-) positions. Thus, the nitration of toluene using a mixture of nitric and sulfuric acids yields, in sequence, the mononitro and dinitro derivatives and then 2,4,6-trinitrotoluene (TNT). Transformations of the methyl group occur through a radical mechanism. For example, chlorination under ultraviolet irradiation and with heating leads to benzyl chloride, C₆H₅CH₂C1, benzal chloride, C₆H₅CHC1₂, and trichloromethylbenzene, C₆H₅CC1₃. Nitration with a solution of HNO₃ in acetic acid yields α-nitrotoluene, C₆H₅CH₂NO₂, and oxidation yields benzyl alcohol, C₆H₅CH₂OH, benzaldehyde, C₆H₅CHO, and benzoic acid, C₆H₅COOH.

Toluene is used in the manufacture of dyes, explosives, pharmaceuticals, and various intermediates. It is also used as a solvent in the production of plastics, paints, varnishes, and printing inks, as well as in the rubber industry.

Toluene is less toxic than benzene. The maximum permissible concentration of toluene vapor in the air is 0.05 mg per liter.

B. L. DIATKIN

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.