Diethyl Ether - Production

Production

Most diethyl ether is produced as a byproduct of the vapor-phase hydration of ethylene to make ethanol. This process uses solid-supported phosphoric acid catalysts and can be adjusted to make more ether if the need arises. Vapor-phase dehydration of ethanol over some alumina catalysts can give diethyl ether yields of up to 95%.

Diethyl ether can be prepared both in laboratories and on an industrial scale by the acid ether synthesis. Ethanol is mixed with a strong acid, typically sulfuric acid, H₂SO₄. The acid dissociates in the aqueous environment producing hydronium ions, H₃O+. A hydrogen ion protonates the electronegative oxygen atom of the ethanol, giving the ethanol molecule a positive charge:

CH₃CH₂OH + H₃O+ → CH₃CH₂OH₂+ + H₂O

A nucleophilic oxygen atom of unprotonated ethanol displaces a water molecule from the protonated (electrophilic) ethanol molecule, producing water, a hydrogen ion and diethyl ether.

CH₃CH₂OH₂+ + CH₃CH₂OH → H₂O + H+ + CH₃CH₂OCH₂CH₃

This reaction must be carried out at temperatures lower than 150 °C in order to ensure that an elimination product (ethylene) is not a product of the reaction. At higher temperatures, ethanol will dehydrate to form ethylene. The reaction to make diethyl ether is reversible, so eventually an equilibrium between reactants and products is achieved. Getting a good yield of ether requires that ether be distilled out of the reaction mixture before it reverts to ethanol, taking advantage of Le Chatelier's principle.

Another reaction that can be used for the preparation of ethers is the Williamson ether synthesis, in which an alkoxide (produced by dissolving an alkali metal in the alcohol to be used) performs a nucleophilic substitution upon an alkyl halide.