The Claisen Condensation

The Claisen Condensation - The Claisen Condensation The...

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The Claisen Condensation The Claisen condensation is a reaction of two ester molecules in which the acyl portion of one ester molecule is transferred to the α carbon of the second. The product of this transfer is a β-keto ester. The reaction is carried out in base; the alkoxide ion corresponding to the alkoxy portion of the ester is commonly used (for example, sodium ethoxide is used with ethyl esters). The base initiates the reaction by removing an α hydrogen from one of the ester molecules, generating an enolate ion. This enolate ion then carries out a nucleophilic substitution on another molecule of ester. The reaction mechanism is shown below. The reaction requires a full equivalent of base. The reason for this is found in step 4 of the mechanism. The hydrogens in the β-keto ester product that are α to both of the carbonyl groups are sufficiently acidic that the product is completely converted to its highly-stabilized enolate ion by ethoxide ion. Addition of aqueous acid to the reaction
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The Claisen Condensation - The Claisen Condensation The...

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