Preparation of Haloalkanes
by Halide Exchange Reactions

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.

Preparation of Alkyl Iodides

Finkelstein reaction is generally used to prepare alkyl iodides.

Finkelstein Reaction

In Finkelstein reaction, chloroalkanes or bromoalkanes are heated with sodium iodide in acetone or methanol to produce iodoalkanes.

Finkelstein reaction

Convert the following :

preparation of ethyl iodide from ethanol

Preparation of Alkyl Fluorides

Swart's reaction is generally used to prepare fluoroalkanes.

Swart's Reaction

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.

Swart's reaction

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.

Swarts reaction : when 2 or 3 halogens are to be replaced, use SbF3 etc.

Convert the following :

Preparation of fluoropropane from propene