VITEEE 2018 Paper

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.
CH3−

CH3 |

C

| CH3

−Br + N

+

a

−

O

- CH3 →

CH3− C | CH3 =CH2

2−Methylpropene

+ NaBr + CH3OH
It is because alkoxides are not only nucleophiles but strong bases as well. They react with alkyl halides leading to elimination reactions.