Furthermore, many examples are known for higher numbers of carbon as well as related compounds containing bromine.Uses include refrigerants, blowing agents, propellants in medicinal applications and degreasing solvents.Illustrative is the synthesis of chlorodifluoromethane from chloroform: The brominated derivatives are generated by free-radical reactions of the chlorofluorocarbons, replacing C-H bonds with C-Br bonds.
The main advantage of this method of deducing the molecular composition in comparison with the method described in the paragraph above is that it gives the number of carbon atoms of the molecule.
The CFCs are far less flammable than methane, in part because they contain fewer C-H bonds and in part because, in the case of the chlorides and bromides, the released halides quench the free radicals that sustain flames.
The densities of CFCs are higher than their corresponding alkanes.
In searching for a new refrigerant, requirements for the compound were: low boiling point, low toxicity, and to be generally non-reactive.
In a demonstration for the American Chemical Society, Midgley flamboyantly demonstrated all these properties by inhaling a breath of the gas and using it to blow out a candle During World War II, various chloroalkanes were in standard use in military aircraft, although these early halons suffered from excessive toxicity.