Coal tar chemicals

Coal tar, coal tar pitch, and coal tar creosote are very similar mixtures obtained from the distillation of coal tars. The physical and chemical properties of each are similar, although limited data are available for coal tar and coal tar pitch. 

Coal tars are by-products of the carbonization of coal to produce coke and/or natural gas. Physically, they are usually viscous liquids or semisolids that are black or dark brown with a naphthalene-like odor. The coal tars are complex combinations of PAHs, phenols, heterocyclic 

By comparison, coal tar creosotes are distillation products of coal tar. They have an oily liquid consistency and range in color from yellowish-dark green to brown. The coal tar creosotes consist of aromatic hydrocarbons, anthracene, naphthalene, and phenanthrene derivatives. At least 75% of the coal tar creosote mixture is PAHs. Unlike the coal tars and coal tar creosotes, coal tar pitch is a residue produced during the distillation of coal tar. The pitch is a shiny, dark brown to black residue that contains PAHs and their methyl and polymethyl derivatives as well as heteronuclear compounds. 

As an aside, the nomenclature of the coal tar industry, like that of the petroleum industry (Speight, 2007), needs refinement and clarification. Almost any black, undefined, semisolid-to-liquid material is popularly, and often incorrectly, described as tar or pitch whether it be a manufactured product or a naturally occurring substance (Chapter 16). However, to be correct and to avoid any ambiguity, use of these terms should be applied with caution. The term tar is usually applied to the volatile and nonvolatile soluble products that are produced during the carbonization or destructive distillation (thermal decomposition with the simultaneous removal of distillate) of various organic materials. By way of further definition, distillation of the tar yields an oil (volatile organic products often referred to as benzole) and a nonvolatile pitch. In addition, the origin of the 

the eventual primary products of the carbonization process (Chapter 16) are coke, coal tar, and crnde benzole (which should not be mistaken for benzene although benzene can be isolated from benzole), ammonia liquor, and gas. The benzole fraction contains a variety of compounds, both aromatic and aliphatic in nature, and can be conveniently regarded as an analog of petroleum naphtha (Speight, 2007). 

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The discovery that usehil chemicals could be made from coal tar provided the foundation upon which the modem chemical industry is built. Industrial chemistry expanded rapidly in the late nineteenth century in German laboratories and factories where coal-tar chemicals were refined and used in synthesis of dyes and pharmaceuticals. But coal-tar production has an eadier origin, dating back to the discovery by William Murdock in 1792 that heating coal in the absence of air generated a gas suitable for lighting. Murdock commercialized this technology, and by 1812 the streets of London were illuminated with coal gas (1). 

Most coal-tar chemicals are recovered from coproduct coke ovens. Since the primary product of the ovens is metallurgical coke, production of coal chemicals from this source is highly dependent on the level of activity in the steel industry. In past years most large coke producers operated thein own coproduct recovery processes. Because of the decline in the domestic steel industry, the recent trend is for independent refiners to coUect cmde coal tars and light oils from several producers and then separate the marketable products. 

In 1990, U.S. coke plants consumed 3.61 x 10 t of coal, or 4.4% of the total U.S. consumption of 8.12 x ICf t (6). Worldwide, roughly 400 coke oven batteries were in operation in 1988, consuming about 4.5 x 10 t of coal and producing 3.5 x 10 t metallurgical coke. Coke production is in a period of decline because of reduced demand for steel and increa sing use of technology for direct injection of coal into blast furnaces (7). The decline in coke production and trend away from recovery of coproducts is reflected in a 70—80% decline in volume of coal-tar chemicals since the 1970s. 

Most coal chemicals are obtained from high temperature tar with an average yield over 5% of the coal which is carbonized. The yields in coking are about 70% of the weight of feed coal. Tars obtained from vertical gas retorts have a much more uniform chemical composition than those from coke ovens. Two or more coals are usually blended. The conditions of carbonization vary depending on the coals used and affect the tar composition. Coal-tar chemicals include phenols, cresols, xylenols, benzene, toluene, naphthalene, and anthracene. 

With the advent of World War I in the summer of 1914, the United States (U.S.) chemists and the chemical industry were propelled into the public arena. At the time, the Germans dominated the chemical industry. However, shipments of chemicals from Germany to the U.S. were thwarted by the British blockade. Consequently, several American Chemical Society (ACS) chapters called on U.S. chemical companies to expand production into dyestuffs, pharmaceuticals, and other organic chemicals. The war effort led to expansions in the steel and petroleum industries which stimulated growth in the production of coal-tar chemicals and petrochemicals that the chemical industry could convert to dyes, drugs, and other products. This lessened the dependence on Germany. The increased demand for explosives called for increased supplies of toluene, phenol and nitric acid (Skolnik Reese, 1976). 

Catechol occurs naturally in fruits and vegetables such as onions, apples and crude beet sugar, and in trees such as pine, oak and willow. Catechol may be released to the environment during its manufacture and use. It has been detected at low levels in ambient and urban air, groundwater, drinking-water and soil samples. It has been foimd in wastewaters from coal conversion, coal-tar chemical production and bituminous shale (United States National Library of Medicine, 1997). It is present in cigarette smoke at 100-360 gg per cigarette (lARC, 1986). 

CoalTar Coal tar chemicals are found in makeup and many hair dyes. Certain colors are probable carcinogens others have been found to cause cancer when applied to skin. Nothingyou wantyour fetus basting in. 

Mononitronapthalene is the product of the nitration of napthalene with a mixed acid mixture of nitric and sulfuric acids at 50 degrees centigrade. Napthalene is a common coal tar chemical. It should be available in the form of moth balls. Check the ingredient lable of moth balls to find the active ingredient. 

Use and exposure There are three forms of xylene meto-xylene, ortho-xyltnt, and para-xylene (m-, o-, and p-xylene). These different forms are referred to as isomers. Xylene is a colorless, sweet-smelling liquid that catches tire easily. It occurs naturally in petroleum and coal tar. Chemical industries produce xylene from petroleum. Xylene is used as a solvent in the printing, rubber, and leather industries. It is also used as a cleaning agent, a thinner for paint, and in paints and varnishes. It is found in small amounts in airplane fuel and gasoline. Xylene is used extensively in the manufacture of many other chemicals, such as plastics, synthetic fibers, pesticides, insect repellents, and leather goods. ... 

Druzhinin VG et al. 2000. Cytogenic disorders in workers of coal-tar chemical industry. Medistina Truda i Promyschlennaya Ekologiya 10 22-23. 

Croda International. This group of companies started with the manufacture of lanolin from wool greases, and oleochemicals, i.e. glycerides, fatty acids and compounds derived from them, remain an area of major importance. Other areas of interest include coal-tar chemicals heterocyclic compounds polymers used in adhesives, inks, paints and resins and foodstuffs. Manufacturing locations are centred on Humberside, Wolverhampton and Leek in Staffordshire. 

The young North American chemical industry had not been able to enter the coal-tar chemical business founded by the British because of the domination by the German cartel. But the door to this opportunity swung wide open during the war. Hooker built the first monochlorobenzene plant in the U.S. in 1915. Warner, Dow and others were already selling chlorine as carbon tetrachloride and chloroform. Dow was soon to follow with chlorobenzene, phenol, indigo and others, and they all impacted chlor-alkali consumption. The future of this important segment of the electrochemical industry was clearly in the hands of these new uses for chlorine. 

These reactions created new chemical compounds from the organic (or carbon) base, which is what made them synthetic organic chemicals. Because manufacturers obtained their crude organic raw materials from coal tar for decades, synthetic organic chemicals were just as often called coal tar chemicals. 

Du Font s inexperience with coal tar chemicals encouraged its... 

Forrestal, Faith, Hope and 5000 The Story of Monsanto, 23, 25-30 quotation of Jules H. Kemen, a long-term employee recalling Queeny, on 35 U.S. Tariff Commission, Census of Dyes and Coal-Tar Chemicals, 1918, 43-44. 

U.S. Tariff Commission, Census of Dyes and Coal-Tar Chemicals, 1918, 39-43. 

Whitaker editorial, Analysis of the Coal-Tar Dye Industry and the committee s report, Recommendations of the New York Section of the American Chemical Society on the Enlargement of the Coal Tar Chemical Industry in the United States, JIEC 6 (December 1914) 972-75. 

For example, Breithut, The German Coal-Tar Chemical Industry (1923) Breithut, British Dyestuffs Industry (1924) Delahanty, The German Dyestuffs Industry (1924). Breithut was a professor of chemistry at the City College of New York from 1903 to 1930. Dr. F. E. Breithut, Ex-Professor, 61, New York Times, May 13, 1962, p. 88 (the newspaper erred in its math Breithut was eighty-one at his death). 

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