Claisen Condensation - Reaction, Mechanism, and Examples

Claisen condensation - Reaction, Mechanism, and Examples are described in this article.

Claisen condensation is a chemical reaction is used for the synthesis of β-keto esters. It is a Named reaction in organic chemistry. It is C-C coupling reaction in organic chemistry. 

Key words: Coupling reaction, Ester, β-keto ester, Name reaction.

Table of Contents

1. Introduction
2. General Reaction & Mechanism
3. Examples
4. Conclusion

1. Introduction

Claisen condensation is a carbon-carbon coupling reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base, resulting in a β-keto ester or a β-diketone. The reaction is named after Rainer Ludwig Claisen in the year 1887. In general metal oxides like sodium methoxide (NaOMe) or sodium ethoxide (NaOEt) are used in this reaction.

2. General reaction & Mechanism

Figure 1: Claisen condensation

There are three types of reactions;

1. Self condensation: The coupling occurs between two molecules of identical ester compounds.

2. Mixed condensation: The coupling occurs between two molecules of different ester compounds.

3. Intra-molecular condensation: The coupling occurs in the same molecule to form cyclic compound. This is also known as Dieckmann condensation. 

Mechanism

Step 1: Deprotonation of ester compound to form enolate ion.

Step 2: Nucleophilic attack of enolate ion on other ester molecule to produce highly resonance-stabilized enolate anion.

Step 3: Finally aqueous acid is added to neutralize enolate ion and remaining base. 

Figure 2: Mechanism of Claisen condensation

3. Examples 

Figure 3: Examples of Claisen condensation

4. Conclusion

To Summarize this article, Claisen condensation is a chemical reaction is used for the synthesis of β-keto esters. It is a Named reaction in organic chemistry. It is C-C coupling reaction in organic chemistry that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base, to provide β-keto ester or a β-diketone. In this article we have studied general reaction and mechanism of Claisen condensation reaction.

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