Methods of Preparation - Halogen Exchange Reaction

Description:

Finkelstein Reaction − By reacting R − Cl and R − Br with NaI in acetone, alkyl iodides can be obtained.

This is an equilibrium reaction.

R - X + NaI ⇌ R - I + NaX (X = Cl, Br)

C₂H₅ - Cl + NaI ⇌ C₂H₅ - I + NaCl

• The reaction is driven in the forward direction by exploiting the difference in solubility of alkyl halides in acetone.

• NaI is soluble in acetone, while NaCl or NaBr are not. These precipitate in acetone and thus, the reaction is favoured according to Le Chatelier’s principle.

Swartz Reaction −  Alkyl fluorides can be obtained by heating RBr/RCl in the presence of a metallic fluoride such as AgF, SbF₃, Hg₂F₂, CoF₂

CH₃Br + AgF → CH₃F + AgBr