Williamson's Synthesis.

⇒It is the laboratory method for the preparation of ethers. 

⇒It is a nucleophilic substitution reaction and proceeds through the SN2 mechanism.

⇒ Order of reactivity of primary halide is CH3X > CH3CH2X > CH3CH2CH2X. 

⇒ Tendency of alkyl halide to undergo elimination is 3º > 2º > 1°. 

⇒ For better yield alkyl halide should be primary and alkoxide should be secondary or tertiary.