A special numbering system is used for fluorinated alkanes, prefixed with Freon-, R-, CFC- and HCFC-, where the rightmost value indicates the number of fluorine atoms, the next value to the left is the number of hydrogen atoms plus 1, and the next value to the left is the number of carbon atoms less one (zeroes are not stated), and the remaining atoms are chlorine.
Freon-12, for example, indicates a methane derivative (only two numbers) containing two fluorine atoms (the second 2) and no hydrogen (1-1=0). Another, easier equation that can be applied to get the correct molecular formula of the CFC/R/Freon class compounds is this to take the numbering and add 90 to it.
Many CFCs have been widely used as refrigerants, propellants (in aerosol applications), and solvents.
Because CFCs contribute to ozone depletion in the upper atmosphere, the manufacture of such compounds has been phased out under the Montreal Protocol, and they are being replaced with other products such as hydrofluorocarbons (HFCs) As in simpler alkanes, carbon in the CFCs bonds with tetrahedral symmetry.
The value of this equation is always a three figure number.
An easy example is that of CFC-12, which gives: 90 12=102 -.
Freon is a trade name for a group of CFCs which are used primarily as refrigerants, but also have uses in fire-fighting and as propellants in aerosol cans. He developed an effective exchange agent to replace chloride in carbon tetrachloride with fluoride to synthesize CFC-11 (CCl), which are toxic but were in common use.
In searching for a new refrigerant, requirements for the compound were: low boiling point, low toxicity, and to be generally non-reactive.
In general the density of these compounds correlates with the number of chlorides.Isomers, which are common for ethane and propane derivatives, are indicated by letters following the numbers : ) was used in fire extinguishers and glass "anti-fire grenades" from the late nineteenth century until around the end of World War II.Experimentation with chloroalkanes for fire suppression on military aircraft began at least as early as the 1920s. The Belgian scientist Frédéric Swarts pioneered the synthesis of CFCs in the 1890s.The production of the anesthetic 2-bromo-2-chloro-1,1,1-trifluoroethane ("halothane") is illustrative: .Ozone absorbs UV-B radiation, so its depletion allows more of this high energy radiation to reach the Earth's surface.