Freon-12 is made by CCl4 by the Swart’s reaction, as shown below:
3CCl4 + 2SbF3 ⟶ 3CCl2F2(Freon−12) + 2SbCl3
Swarts’ reaction is generally used to get alkyl fluorides from alkyl chlorides or alkyl bromides. This is done by heating of the alkyl chloride/bromide in the presence of the fluoride of some heavy metals (silver fluoride or mercurous fluoride for example). The reaction will proceed if sodium fluoride or potassium fluoride is used, but the resulting yield will be significantly lower. This process was first reported by Frederic Jean Edmond Swarts in 1892.