Principle
When excess ethyl alcohol (ethanol) is heated with conc. H₂SO₄ at 140⁰C, diethyl ether or ethoxyethane is obtained.

CH3CH2OH + conc.H2SO4 → CH3CH2HSO4 + H2O
CH3CH2HSO4 + CH3CH2OH → CH3CH2-O-CH2CH3

Figure

Procedure
50 cc of conc. H2SO4 is gradually added with constant shaking to 100 cc of ethyl alcohol kept in the distillation flask. The mixture is heated on the water bath at 140⁰C. When ether begins to distill over, alcohol is added in the distillation flask from the dropping funnel at nearly the same rate as that of the distillation, the temperature being maintained at 140⁰C.

Purification
The distillate contains ether, ethyl alcohol, water, and sulphur dioxide. It is first washed with dil. NaOH solution and then with water. The upper layer is separated and dried over anhydrous CaCl₂. It is then redistilled on a water bath pure ether passes over at 34-35⁰C.