Question

Ethers can be prepared by Williamson synthesis in which an alkyl halide is reacted with sodium alkoxide. Di-tert -butyl ether can't be prepared by this method.Explain.

Answer 1

In order to prepare di-tert- butyl ether, sodium tert-butoxide must be reacted with tert - butyl bromide. Alkoxides are not only nucleophiles but they are strong base as well. They react with $3^{\circ }$ alkyl halides leading to the elimination reaction.
When tert - butyl- bromide reacts with sodium tert-butoxide instead of substitution, elimination, takes place. As a result of this elimination reaction, Isobutylene is formed instead of di - tert butyl ether.