Problems with carbon dating accuracy

The production of the anesthetic 2-bromo-2-chloro-1,1,1-trifluoroethane ("halothane") is illustrative: .

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.

CFCs and HCFCs are usually produced by halogen exchange starting from chlorinated methanes and ethanes.

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 densities of CFCs are higher than their corresponding alkanes.