Title: Chlorofluorocarbons
Additional Names: CFCs; FCCs
Literature References: Chemically stable series of chlorinated and fluorinated compounds usually with methane or ethane skeleton, marketed under general names such as Arcton (ICI) , Freon (DuPont) , Frigen (Hoechst) , Genetron (AlliedSignal) . Known collectively as CFCs, individually identified by a CFC code based on the "rule of 90". (To derive the chemical formula for CFC-12, e.g., add "90" to 12; the resulting number "102" indicates 1 carbon, 0 hydrogen, 2 fluorine yielding the formula CCl2F2.) Initial report on suitability as refrigerants: T. Midgley, Jr., A. L. Henne, Ind. Eng. Chem. 22, 542 (1930). Review including physical and chemical properties of various CFCs: E. Heiskel, Aerosol Rep. 22, 403-415 (1983). CFCs do not decompose in the lower atmosphere. Photodecomposition occurs in the stratosphere via absorption of uv radiation and subsequent release of atomic chlorine which can catalyze ozone breakdown. CFC-ozone depletion hypothesis: M. J. Molina, F. S. Rowland, Nature 249, 810 (1974). Reviews focusing on atmospheric chemistry of CFCs, uses, potential hydrogen-substituted replacements, environmental and regulatory issues: J. P. Cohn, BioScience 37, 647-650 (1987); R. Pool, Science 242, 666-668 (1988); F. S. Rowland, Environ. Conserv. 15, 101-115 (1988); L. B. Weisfeld, Plast. Compd. 1988, 15-22, 40-43; F. S. Rowland, Am. Sci. 77, 36-45 (1989). For prepn information see dichlorodifluoromethane (CFC-12), trichlorofluoromethane (CFC-11), cryofluorane (CFC-114).
Properties: Colorless, essentially odorless, nonflammable, noncorrosive. Miscible with aliphatic, alicyclic and aromatic hydrocarbons, halogenated hydrocarbons, monovalent low molecular alcohols.
NOTE: Consult latest Government regulations on use as aerosol propellant.
Use: In aerosol propellants (CFC-11, 12, 113); air conditioning; refrigeration (CFC-12); blowing agents for making foam (CFC-11, 12); cleaning fluids (CFC-113); solvents for the electronics industry, bedding and packaging. |