Question

In Williamson synthesis, if a tertiary alkyl halide is used, then ______.

Options

• ether is obtained in good yield

• ether is obtained in poor yield

• alkene is the only reaction product

• a mixture of alkene as a major product and ether as a minor product forms

Answer 1

In Williamson synthesis, if a tertiary alkyl halide is used, then alkene is the only reaction product.

Explanation:

If a tertiary alkyl halide is used, an alkene is the only reaction product and no ether is formed.

For example, the reaction of CH₃ONa with (CH₃)₃C–Br gives exclusively 2-methylpropene.

\[\ce{(CH3)3-C-Br + \overset{+}{N}a\overset{\overset{-}{\bullet\bullet}}{\underset{\bullet\bullet}{O}} - CH3 -> \underset{2-Methylpropene}{(CH3)2 - C = CH2} + NaBr + CH3OH}\]

It is because alkoxides are not only nucleophiles but strong bases as well. They react with alkyl halides, leading to elimination reactions.