Illustrate with examples the limitations of Williamson synthesis for the preparation of certain types of ethers.

(N/A) The Williamson synthesis involves the $S_{N}2$ attack of an alkoxide ion on a primary alkyl halide.
For example: $(CH_3)_3CONa + CH_3Cl \rightarrow (CH_3)_3COCH_3 + NaCl$
However,if secondary or tertiary alkyl halides are used instead of primary alkyl halides,elimination competes with substitution.
As a result,alkenes are produced instead of ethers because alkoxides act as both nucleophiles and strong bases.
For example: $(CH_3)_3CCl + NaOCH_3 \rightarrow CH_3-C(CH_3)=CH_2 + CH_3OH + NaCl$