In halide exchange reactions, the halide of an alkyl halide gets replaced by another halide. Alkyl iodides and alkyl fluorides are generally prepared by halide exchange reaction.
Finkelstein reaction is generally used to prepare alkyl iodides.
In Finkelstein reaction, chloroalkanes or bromoalkanes are heated with sodium iodide in acetone or methanol to produce iodoalkanes.
Swart's reaction is generally used to prepare fluoroalkanes.
In Swart's reaction, inorganic fluorides (e.g. AgF, Hg2F2, CoF2, CoF3, SbF3 etc) are heated with suitable haloalkanes to produce alkyl fluorides.
Example : In the following reaction, methyl fluoride is prepared by heating methyl bromide with silver(I) fluoride.
CoF3, SbF3 are used when the haloalkane contains more than one halides on the same carbon.
Example : 2,2-Dichloropropane is heated with antimony trifluoride (SbF3) to form 2,2-difluoropropane.