Benzoin & Perkin Condensation

Contents

• Benzoin condensation

• Perkin condensation

Learning Objectives

At the end of this lecture, student will be able to

• Explain the mechanism involved in benzoin and Perkin condensation

Benzoin Condensation

• Self condensation of aromatic aldehydes in the presence of CN‾  as catalyst

• Aqueous ethanolic NaCN or KCN

• Product - α hydroxy ketone

Mechanism of Benzoin Condensation

Perkin Condensation

• Condensation reaction between aromatic aldehyde and aliphatic anhydride

• Catalyst – Na or K salt of the same acid

• Product – α,β - unsaturated acids

Mechanism of Perkin Condensation

Knoevenagel Condensation

• Condensation of an aldehyde or a ketone that has no α hydrogens and a compound with active methylene group

Summary

• Benzoin condensation – self condensation of aromatic aldehydes in the presence of CN‾ as catalyst

• Product - α hydroxy ketone

• Perkin condensation – reaction   between aromatic aldehyde and aliphatic anhydride with Na or K salt of the same acid as catalyst

• Product – α,β - unsaturated acids