Mechanism of Claisen Condensation Reaction
The Claisen condensation is a carbon-carbon bond-forming reaction that involves the formation of a β-keto ester or a β-diketone. The reaction proceeds through three main steps: enolate formation, nucleophilic attack, and removal of the leaving group.
- Enolate formation: An α-proton from an ester is removed by a strong base, such as a sodium alkoxide, to form an enolate ion. The delocalization of electrons stabilizes the enolate ion. This can be represented by the general reaction:
RCOOR’ + OR– (base) → R’-COO– + R-OH
- Nucleophilic attack: The enolate ion acts as a nucleophile and attacks the carbonyl carbon of a second ester molecule, forming a tetrahedral alkoxide intermediate.
General reaction: R’-C(=O)O– + R”-CO-R”’ → R’-C(=O)-O-R” + R”-C(=O)-R”‘
- Removal of the leaving group: The alkoxide ion reforms the carbonyl group, and the leaving group (usually an alkoxide) is eliminated.
General reaction: R’-C(=O)-O-R” → R’-C(=O)-R” + ROH
Claisen condensation is reversible, and the equilibrium can be driven forward by removing the acidic β-keto ester product formed during the reaction. This principle is known as Le Chatelier’s principle.
Claisen Condensation
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.