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Claisen condensation

Reaction Mechanism of Claisen condensation

Esters with α-hydrogen atom on treatment with a strong base, e.g. C2H5ONa, undergo self condensation to produce β-keto esters.

Claisen condensationCH3COCH2COOC2H5

An α-hydrogen in an ester is weakly acidic than  the α-hydrogen of aldehydes or ketones, because the carbonyl group helps accommodate the negative charge of the carbanion to a lesser extent.

When ethyl acetate is treated with sodium ethoxide, and the resulting mixture is acidified, ethyl 3-oxobutanoate, generally known as ethyl acetoacetate or acetoacetic ester is obtained.

Claisen condensation

Mixed Claisen Condensation

Claisen condensation

A reaction similar to a mixed Claisen condensation is the condensation of the ketone and an ester. Because the α-hydrogens of a ketone are more acidic than those of an ester, primarily one product is formed if the ketone is added slowly to a mixture of the base and excess ester. The product is a β-diketone.

Claisen condensation

A β-keto aldehyde is formed when a ketone condenses with formate esters.

Claisen condensation

A β-keto ester is formed when a ketone condenses with diethyl carbonate.

Claisen condensation

Intramolecular Claisen Condensation

Dieckmann Condensation: The addition of base to a 1,6-diester causes the diester to undergo intramolecular Claisen Condensation, thereby forming a five membered ring β-keto ester. An intramoelcular Claisen Condensation is called a Dieckmann Condensation.

Claisen condensation

Example of Claisen condensation

Reaction Mechanism of Claisen condensation

List of Name Reaction of Organic Chemistry consist of detail Reaction Mechanism of all name reactions of Organic Chemistry.

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