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10.0 Introduction

  • Page ID
    44221
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    FreonsTM, also called fluorocarbons or chlorofluorocarbons, have been a source of concern to environmentalists since 1974, when Frank S. Rowland and Mario J. Molina suggested that these substances might be contributing to the destruction of Earth’s ozone layer. The stratospheric ozone layer filtres out much of the ultraviolet radiation from the sun’s rays, and it is believed that extensive depletion of this layer, and the consequent increase in the amount of ultraviolet radiation reaching Earth, could result in the
    destruction of certain crops, in climate modification, and in an increase in the incidence of skin cancer. In recent years, the manufacture and use of freons has declined sharply as the general public has become more aware of the problems that might be caused by these substances.



    Note: “Freon” is a DuPont trademark.


    Related to the freons are the halons—now used in some fire extinguishers, particularly in areas where foams or dry-chemical extinguishers cannot be used (e.g., in and around computers). If you examine such extinguishers, you will find that the halon is identified by a number; for example, halon 1301 or halon 1211. The first number represents the number of carbon atoms present, the second represents the number of fluorines, the third shows the number of chlorines, and the fourth the number of bromines. Thus the halons given as examples above have the following structures:

    You need not remember the names of the various freons and halons, but you should be prepared to name them by the IUPAC system according to the rules developed in the next section.

    Contributors

    Dr. Dietmar Kennepohl FCIC (Professor of Chemistry, Athabasca University)



    10.0 Introduction is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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