The reactants used in Williamson’s synthesis of ethers are

Williamson ether reaction is used for the preparation of ether using an alkoxide and primary haloalkane. In this reaction, there is an ${\mathrm{SN}}_2$ attack of an alkoxide ion on primary alkyl halide

$\underset{\mathrm{primary} \mathrm{haloalkane}}{\mathrm{R}-\mathrm{X}}+{\mathrm{Na}}^{+} {}^{-}\mathrm{OR}\to \underset{\mathrm{Ether}}{\mathrm{R}-\mathrm{O}-\mathrm{R}}$