Return to Contents  Chapter 17: Aldehydes and Ketones. Nucleophilic Addition to C=O  Ch 17 contents

The Baeyer-Villager Reaction

Baeyer-Villager of an ketone

Baeyer-Villager for an aldehyde

Reaction type:  Oxidation-reduction via Nucleophilic addition


the O atom inserts on the more substituted side of the carbonyl In this example the primary ethyl group migrates in preference to the methyl group so we end up with an ethyl ester.
Baeyer-Villager reaction of a cyclic ketone

unsymmetrical cyclic example

In this example the O ends up on the more substituted side.

Study Tip:
It's easy to make an avoidable mistake here, especially with the cyclic systems and loose a C atom.

Count C atoms!

In the example above, the 5-membered ring becomes a 6-membered ring because an O atom has been added to the cyclic system.

Related Reactions

Step 1:
An acid/base reaction. Protonation of the carbonyl activates it while creating a more reactive nucleophile, the percarboxylate.
mechanism of the Baeyer-Villager reaction
Step 2:
Now the nucleophilic O attacks the carbonyl C with the electrons from the C=O π bond going to the positive O.
Step 3:
Electrons from the O come back (this reforms the π bond of the C=O) and we migrate the C-C electrons to form a new C-O bond displacing the carboxylate as a leaving group.
Step 4:
Finally an acid/base reaction reveals the C=O and therefore the ester product.

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© Dr. Ian Hunt, Department of Chemistry, University of Calgary