Meaning of CHEMICAL INDUSTRY in English

CHEMICAL INDUSTRY

complex of processes, operations, and organizations engaged in the manufacture of chemicals and their derivatives. Although the chemical industry may be described simply as the industry that uses chemistry and manufactures chemicals, this definition is not altogether satisfactory because it leaves open the question of what is a chemical. Definitions adopted for statistical economic purposes vary from country to country. Also the Standard International Trade Classification, published by the United Nations, includes explosives and pyrotechnic products as part of its chemicals section. But the classification does not include the man-made fibres, although the preparation of the raw materials for such fibres is as chemical as any branch of manufacture could be. Additional reading Encyclopaedic coverage of every aspect of the chemical industry is provided by Herman F. Mark et al. (eds.), Encyclopedia of Chemical Technology, 3rd ed., 31 vol. (1978-84), formerly known as Kirk-Othmer Encyclopedia of Chemical Technology, with a 4th edition begun in 1991; Ullmann's Encyclopedia of Industrial Chemistry, 5th, completely rev. ed., edited by Wolfgang Gerhartz et al. (1985- ); and Thorpe's Dictionary of Applied Chemistry, 4th ed., 12 vol. (1937-56). Books covering the technology of the chemical industry include R.N. Shreve, Chemical Process Industries, 3rd ed. (1967); and E.R. Riegel, Industrial Chemistry, ed. by James A. Kent (1962). Works covering the chemical industry from the industrial and statistical point of view include: Conrad Berenson (ed.), The Chemical Industry: Viewpoints and Perspectives (1963); Jules Backman, The Economics of the Chemical Industry (1970); Organization for Economic Cooperation and Development, The Chemical Industry . . . (annual); United Nations, Economic Commission for Europe, Market Trends and Prospects for Chemical Products, 3 vol. (1969); and Alfons Metzner, Die chemische Industrie der Welt, vol. 1, Europa, vol. 2, Uebersee (1955).Good coverage of sections of the chemical industry is provided by: W.L. Faith, D.B. Keyes, and R.L. Clark, Industrial Chemicals, 3rd ed. (1965), a description of the economics and technology of 137 chemical products; P.H. Groggins, Unit Processes in Organic Synthesis, 5th ed. (1958); and E. Kilner and D.M. Samuel, Applied Organic Chemistry (1960). Anthony Standen The Editors of the Encyclopdia Britannica Organic chemicals The heavy chemical industry, in its classical form, was based on inorganic chemistry, concerned with all the elements except carbon and their compounds, but including, as has been seen, the carbonates. Similarly the light chemical industry uses organic chemistry, concerned with certain compounds of carbon such as the hydrocarbons, combinations of hydrogen and carbon. In the late 1960s the phrase heavy organic chemicals came into use for such compounds as benzene, phenol, ethylene, and vinyl chloride. Benzene and phenol are related chemically, and they are also related to toluene and the xylenes, which can be considered together as part of the aromatic group of organic chemicals, the aromatic compounds being most easily defined as those with chemical properties like those of benzene. Aromatic hydrocarbons Benzene Chemically, the hydrocarbon benzene, which forms the basis of the aromatics, is a closed, six-sided ring structure of carbon atoms with a hydrogen atom at each corner of the hexagonal structure. Thus a benzene atom is made up of six carbon (C) atoms and six hydrogen (H) atoms and has the chemical formula C6H6. Benzene has long been an industrial chemical. Initially it was obtained from the carbonization (heating) of coal, which produces coke, combustible gas, and a number of by-products, including benzene. Carbonization of coal to produce illuminating gas dates back in England to the very early years of the 19th century. The process is still employed in some countries, but more use is being made of natural gas. The carbonizing process is also used (with slight modifications) to produce metallurgical coke, indispensable for the manufacture of iron and hence steel. The supply of benzene from the carbonizing process, however, is not sufficient to meet the demand. For every ton of coal carbonized only about two to three pounds (0.9 to 1.35 kilograms) of benzene are obtained. The shortage of aromatics first became evident during World War I, when toluene was in great demand for the manufacture of trinitrotoluene, or TNT, the principal explosive used then. Methods were worked out to obtain toluene from petroleum. Much later, after World War II, benzene and all the other aromatics derived from it were needed in far greater quantities than metallurgical coke could supply, and by far the greater part of these aromatics now comes from petroleum.

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