coal tar

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coal tar By-product from the manufacture of coke. Coal tar comes from bituminous coal used in the distillation process. It is a volatile substance, important for its organic chemical constituents (coal-tar crudes), which are extracted by further distillation. These include xylene, toluene, naphthalene and phenanthrene, and are the basic ingredients for the synthesis of many products, such as explosives, drugs, dyes and perfumes.

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coal tar, product of the destructive distillation of bituminous coal. Coal tar can be distilled into many fractions to yield a number of useful organic products, including benzene, toluene, xylene, naphthalene, anthracene, and phenanthrene. These substances, called the coal-tar crudes, form the starting point for the synthesis of numerous products—notably dyes, drugs, explosives, flavorings, perfumes, preservatives, synthetic resins, and paints and stains. The residual pitch left from the fractional distillation is used for paving, roofing, waterproofing, and insulation.

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coal tar • n. a thick black liquid produced by the destructive distillation of bituminous coal. It contains benzene, naphthalene, phenols, aniline, and many other organic chemicals.

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coal tar (kohl) n. see tar.