Chapter 17: Aldehydes and Ketones. Nucleophilic Addition to C=O

The Baeyer-Villager Reaction

Reaction type:  Oxidation -reduction via Nucleophilic addition

Summary

• Ketones, RCOR', can be oxidised by peracids to give esters, RCO₂R'.
• It can be viewed as the insertion of O into one of the C-C bonds adjacent to the carbonyl.
• Cyclic ketones give cyclic esters which are also known as lactones.

lactone

• In non-symmetrical cases, it is the more highly substituted alkyl group that migrates : i.e. 3^o R > 2^o R > 1^o R > -CH3

In this example the primary ethyl group migrates in preference to the methyl group

Related Reactions

• Epoxidation of Alkenes

THE BAEYER-VILLAGER REACTION
Step 1: An acid/base reaction. Protonation of the carbonyl activates it while creating a more reactive nucleophile, the percarboxylate.
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.

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