MHTCET 11 Apr 2026 Shift 1 Paper

Concept:Williamson synthesis is a suitable method for ether preparation via an $S_N2$ reaction between an alkoxide ion and an alkyl halide.Explanation:In Williamson synthesis, an alkoxide ion reacts with a methyl or primary alkyl halide to form an ether.The general reaction is:$$R-O^{-}Na^{+} + R'-X \rightarrow R-O-R' + NaX$$For a clean $S_N2$ pathway, the alkyl halide should be methyl or primary to minimize steric hindrance.In option B, sodium tert-butoxide reacts with methyl bromide:$$(\mathrm{CH}_3)_3\mathrm{CONa} + \mathrm{CH}_3\mathrm{Br} \rightarrow (\mathrm{CH}_3)_3\mathrm{COCH}_3 + \mathrm{NaBr}$$This yields tert-butyl methyl ether.Option A is unsuitable because tert-butyl bromide is a tertiary halide and mainly undergoes elimination with sodium methoxide.Therefore, option B is the correct and suitable method.Answer:Option B: Reacting sodium tertiary butoxide and methyl bromide.