chlorofluorocarbon


chlorofluorocarbon
/klawr'oh floor'oh kahr"beuhn, -flawr'-; klohr'oh floor'oh kahr"beuhn, -flohr'-/, n.
any of several volatile, inert, saturated compounds of carbon, fluorine, chlorine, and hydrogen: used as refrigerants, foam-blowing agents, solvents, and, formerly, as aerosol propellants until scientists became concerned about depletion of the atmospheric ozone layer. Cf. chlorofluoromethane.
[1945-50; CHLORO-2 + FLUOROCARBON]

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      any of several organic compounds (organic compound) composed of carbon, fluorine, and chlorine. When CFCs also contain hydrogen in place of one or more chlorines, they are called hydrochlorofluorocarbons, or HCFCs. CFCs are also called Freons (Freon), a trademark of the E.I. du Pont de Nemours & Company (DuPont Company) in Wilmington, Del. CFCs were originally developed as refrigerants during the 1930s. Some of these compounds, especially trichlorofluoromethane (CFC-11) and dichlorodifluoromethane (CFC-12), found use as aerosol-spray propellants, solvents, and foam-blowing agents. They are well suited for these and other applications because they are nontoxic and nonflammable and can be readily converted from a liquid to a gas and vice versa.

      Their commercial and industrial value notwithstanding, CFCs were eventually discovered to pose a serious environmental threat. Studies, especially those of American chemists F. Sherwood Rowland (Rowland, F. Sherwood) and Mario Molina (Molina, Mario) and Dutch chemist Paul Crutzen (Crutzen, Paul), indicated that CFCs, once released into the atmosphere, accumulate in the stratosphere, where they contribute to the depletion of the ozone layer. Stratospheric ozone shields life on Earth from the harmful effects of the Sun's ultraviolet radiation; even a relatively small decrease in the stratospheric ozone concentration can result in an increased incidence of skin cancer in humans and genetic damage in many organisms. Ultraviolet radiation in the stratosphere causes the CFC molecules (molecule) to dissociate, producing chlorine atoms and radicals (radical) (i.e., chlorodifluoromethyl radical; free radicals are species that contain one or more unpaired electrons).

      The chlorine atoms then react with ozone, initiating a process whereby a single chlorine atom can cause the conversion of thousands of ozone molecules to oxygen.

      Because of a growing concern over stratospheric ozone depletion and its attendant dangers, a ban was imposed on the use of CFCs in aerosol-spray dispensers in the late 1970s by the United States, Canada, and the Scandinavian countries. In 1990, 93 nations agreed, as part of the Montreal Protocol (established 1987), to end production of ozone-depleting chemicals by the end of the 20th century. By 1992 the list of participating countries had grown to 140, and the timetable for ending production of CFCs advanced to 1996. This goal has largely been met. HCFCs pose less of a risk than CFCs because they decompose more readily in the lower atmosphere; nevertheless, they too degrade the ozone layer and are scheduled to be phased out by 2030.

Francis A. Carey
 

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Universalium. 2010.

Look at other dictionaries:

  • chlorofluorocarbon — by 1946, from CHLORO (Cf. chloro ) + fluorocarbon, from comb. form of FLUOR (Cf. fluor) + CARBON (Cf. carbon) …   Etymology dictionary

  • chlorofluorocarbon — chlorofluorocarbon, also CFC noun (C) technical …   Longman dictionary of contemporary English

  • chlorofluorocarbon — [klôr΄ō floor′ə kär΄bən, klôr΄ōflôr′ə kär΄bən] n. any of various nontoxic, nonflammable halocarbon organic compounds containing carbon, fluorine, chlorine, and hydrogen, used for plastic foam, as a refrigerant, etc.: these compounds are thought… …   English World dictionary

  • Chlorofluorocarbon — A chlorofluorocarbon (CFC) is an organic compound that contains carbon, chlorine, and fluorine, produced as a volatile derivative of methane and ethane. A common subclass are the hydrochlorofluorocarbons (HCFCs), which contain hydrogen, as well.… …   Wikipedia

  • chlorofluorocarbon — UK [ˌklɔːrəʊˌflʊərəʊˈkɑː(r)bən] / US [ˌklɔroʊˌflʊrəˈkɑrbən] noun [countable, usually plural] Word forms chlorofluorocarbon : singular chlorofluorocarbon plural chlorofluorocarbons chemistry a CFC …   English dictionary

  • chlorofluorocarbon — noun Date: 1949 any of several simple gaseous compounds that contain carbon, chlorine, fluorine, and sometimes hydrogen, that are used as refrigerants, cleaning solvents, and aerosol propellants and in the manufacture of plastic foams, and that… …   New Collegiate Dictionary

  • chlorofluorocarbon — noun Any of a class of organic compounds in which the hydrogen atoms of a hydrocarbon are replaced with those of chlorine and fluorine; formerly used as refrigerants and aerosol can propellants but withdrawn due to causing damage to the ozone… …   Wiktionary

  • chlorofluorocarbon — chlo·ro·flu·o·ro·car·bon (CFC) (klo″ro flooґo ro kahr″bən) any of a group of hydrocarbons in which some or all of the hydrogen atoms are replaced by chlorine or fluorine; some in this group were formerly widely used in aerosols,… …   Medical dictionary

  • chlorofluorocarbon — chlo|ro|fluo|ro|car|bon [ˌklo:rəufluərəuˈka:bən US rouflurouˈka:r ] n [Date: 1900 2000; : Greek; Origin: chloro (from chloros; CHLORINE) + English fluorocarbon] a ↑CFC …   Dictionary of contemporary English

  • chlorofluorocarbon — chlo|ro|fluor|o|car|bon [ ,klɔrou,flurə karbən ] noun count usually plural SCIENCE a CFC …   Usage of the words and phrases in modern English


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