Question

Explain Williamson's Synthesis With One Example.

Answer 1

Williamson's Synthesis;

1. The reaction of alkyl halides with Sodium alkoxide or Sodium phenoxide to form Ether is called Williamson synthesis.
2. It is a process that allows the preparation of a wide range of symmetric and asymmetric Ethers by a ${\mathrm{S}}_{\mathrm{N}}2$ mechanism.
3. In Williamson's synthesis, the Alkyl halide is heated with alcoholic Sodium alkoxide then the Alkoxide ion is a nucleophile that displaces a Halide ion from an alkyl halide to give an ether.
4. Primary Alkyl halides will give a better yield.
5. This method is used for both basic and mixed Ether preparation.

Example:

1. $\underset{\mathrm{Methyl}\mathrm{iodide}}{{\mathrm{CH}}_3\mathrm{I}}+\underset{\mathrm{Alc}.\mathrm{Sodium}\mathrm{ethoxide}}{{\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{ONa}}\to \underset{\mathrm{Ethyl}\mathrm{methyl}\mathrm{ether}}{{\mathrm{CH}}_3-\mathrm{O}-{\mathrm{CH}}_2{\mathrm{CH}}_3}+\underset{\mathrm{Sodium}\mathrm{iodide}}{\mathrm{NaI}}$
2. Methyl iodide is heated with alcoholic Sodium ethoxide then the ethoxide ion acts as a nucleophile which displaces an iodide ion from an methyl iodide to give an Ethyl methyl ether

Therefore, the Williamson's synthesis is the reaction of an Alkyl halide with alcoholic Sodium alkoxide to form alkyl ether