Problems with carbon dating accuracy
Every permutation of fluorine, chlorine and hydrogen based on methane and ethane has been examined and most have been commercialized.Furthermore, many examples are known for higher numbers of carbon as well as related compounds containing bromine.
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.The value of this equation is always a three figure number.An easy example is that of CFC-12, which gives: 90 12=102 -.The densities of CFCs are higher than their corresponding alkanes.
In general the density of these compounds correlates with the number of chlorides.
Thus, methane boils at −161 °C whereas the fluoromethanes boil between −51.7 (CF).
The CFCs have still higher boiling points because the chloride is even more polarizable than fluoride.
Uses include refrigerants, blowing agents, propellants in medicinal applications and degreasing solvents.
Billions of kilograms of chlorodifluoromethane are produced annually as precursor to tetrafluoroethylene, the monomer that is converted into Teflon.
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.