Ch15: 2 ROH -> ROR + H2O

Chapter 15: Alcohols, Diols and Thiols

Synthesis of Ethers via Acid-catalysed Condensation of Alcohols

ether synthesis by alcohol condensation

Reaction type: Nucleophilic Substitution (S_N2)

Summary

Reagents typically H₂SO₄and heat.
In general, typically limited to symmetrical ethers of primary alcohols.
The method is not suitable for unsymmetrical ethers.
The substitution involves the O nucleophile of one alcohol attacking the electrophilic C in the other displacing a water molecule.

QUESTIONS:
Why can this reaction be termed a condensation reaction ? ANSWER
Why is the reaction unsuitable for unsymmetrical ether synthesis ? ANSWER
What is the most likely side reaction that will compete with the substitution ? ANSWER

Related reactions

Williamson ether synthesis

MECHANISM FOR ALCOHOL CONDENSATION TO GIVE AN ETHER
Step 1: An acid/base reaction. Protonation of the alcoholic oxygen to make a better leaving group. This step is very fast and reversible. The lone pairs on the oxygen make it a Lewis base.
Step 2: The O of the second alcohol molecule functions as the nucleophile and attacks to displace the good leaving group, a neutral water molecule, by cleaving the C-O bond. This creates an oxonium ion intermediate.
Step 3: Another acid / base reaction. The proton is removed by a suitable base (here a water molecule, ROH is another alternative) to give the ether product.