What is Claisen Condensation?

Claisen condensation is an organic reaction that forms a new carbon-carbon bond, producing a β-keto ester or a β-diketone. It involves the condensation of two esters or one ester and a carbonyl compound in the presence of a strong base, forming a β-keto ester or a β-diketone.

The reaction proceeds through the deprotonation of an α-hydrogen on an ester by a strong base, creating an enolate ion, which then attacks the carbonyl carbon of a second ester or a carbonyl compound, forming a tetrahedral intermediate. The reaction requires at least one equivalent of a strong base, such as sodium alkoxide, and esters with at least two α-hydrogens to ensure the formation of an enolate ion.

Claisen Condensation Definition

Claisen condensation is a carbon-carbon bond-forming reaction between two esters or one ester and another carbonyl compound in the presence of a strong base. The reaction produces a β-keto ester or a β-diketone.

Claisen Condensation Reagents

Claisen condensation involves using esters or one ester and another carbonyl compound, such as a ketone or an aldehyde, in a strong base. Typical reagents include:

• Enolizable esters: These esters contain an α-hydrogen atom that can be deprotonated to form an enolate ion. Examples include ethyl acetate, methyl propionate, etc.
• Non-enolizable esters (for cross-Claisen condensations): These esters do not have an α-hydrogen and thus cannot form enolates themselves. They act as electrophiles in the reaction. Examples include benzoyl chloride, pivaloyl chloride, etc.
• Strong bases: Commonly used bases include sodium alkoxides like sodium ethoxide (NaOEt) or potassium tert-butoxide (t-BuOK).

Claisen Condensation Reaction

The Claisen condensation is a carbon-carbon bond-forming reaction that occurs between two esters or one ester and another carbonyl compound. The general reaction can be illustrated as follows:

R₁ COCH₂​R₂ + R₃COCH₂​R₄ → R₁COCH₂​CH₂​COR₃ + R₂COCH_2​R₄

This reaction requires at least one of the reagents to be enolizable and a solid base to facilitate the formation of an enolate ion. The product of the reaction is a β-keto ester or a β-diketone.

Claisen condensation is an organic reaction that forms a new carbon-carbon bond, producing a β-keto ester. It involves the condensation of two esters or one ester and a carbonyl compound in the presence of a strong base, forming a β-keto ester or a β-diketone. It was discovered by German chemist Ludwig Claisen in 1887. In this article, we will look into What Claisen Condensation is, its mechanism, examples, types, etc.