Odorant(redirected from Aroma compound)
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a substance added to a gas to impart a distinctive odor to it, mainly for safety purposes. Odorants should be physiologically harmless, nonaggressive with respect to metals and materials used in the construction of gas pipeline networks and devices, and inert to the components of the gas being odorized or to impurities in the gas, and they should not condense under operating conditions. They are usually sulfur-containing compounds; according to composition, a distinction is made between mercaptan odorants (Captan, Calodorant, methyl mercaptan, and ethyl mercaptan) and sulfide odorants (diethyl sulfide, dimethyl sulfide, dimethyl disulfide, and tetrahydrothiophene).
Industrial ethyl mercaptan (C2H5SH), which is characterized by a sharp, unpleasant odor sometimes resembling that of rotten cabbage, is used in the USSR for odorization of natural, shale, and liquefied hydrocarbon gases. As of 1974, work was under way on the introduction of Sul’fan, a high-mercaptan-content odorant composed of unpleasant-smelling organic sulfur compounds that are waste products of sulfate boiling of cellulose. In 1972 a mixture of natural mercaptans present in the gas condensate at the Orenburg gas-condensate deposit (USSR) was proposed for industrial use. Among the odorants used in the USA are petroleum odorants (Pentalarm, composed of ethyl mercaptan and n-amyl mercaptan; Captan, basically a mixture of butyl mercaptans; and Calodorant, containing sulfur almost entirely in the sulfide and disulfide forms), tetrahydrothiophene, and odorants consisting of mixtures of tert-butyl mercaptan or dimethyl sulfide.
Substances used for deodorizing are called deodorants; they include charcoal, chlorinated lime solution, potassium permanganate, and hydrogen peroxide. The use of mixtures of several odorants, which produce a stronger and more stable odor than the individual components, was planned as of 1974.
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L. E. GAVRILOV