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 tert-butyl halides, elimination is favoured over substitution, so alkene is the only reaction product and ether is not formed.

\[\begin{array}{cc}
\phantom{....}\ce{CH3}\phantom{.........}\ce{CH3}\phantom{.......................................}\ce{CH3}\phantom{}\\
\phantom{.}|\phantom{.............}|\phantom{..........................................}|\phantom{}\\
\ce{CH3-C-Br + \overset{+}{N}a\overset{-}{O}C-CH3 -> CH3-C=CH2 + NaBr + CH3-C-OH}\\
\phantom{.}|\phantom{.............}|\phantom{..................}|\phantom{........................}|\phantom{}\\
\phantom{}\ce{\underset{(tert-butyl bromide)}{CH3}}\phantom{....}\ce{CH3}\phantom{..........}\ce{\underset{(2-methylprop-1-ene)}{CH3}}\phantom{..............}\ce{CH3}\phantom{...}
\end{array}\]