Fischer esterification
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Fischer esterification is the process of forming an ester by refluxing a carboxylic acid and an alcohol in the presence of an acid (catalyst).
Acid catalysts
Commonly used acid catalysts for a Fischer esterification include:
Mechanism
- Proton transfer from acid catalyst to carbonyl oxygen increases electrophilicity of carbonyl carbon.
- The carbonyl carbon is attacked by the nucleophilic oxygen atom of the alcohol.
- Formation of an oxonium ion.
- Proton transfer from the oxonium ion to a second molecule of alcohol gives a TCAC
- Proton transfer from one of the hydroxyl groups of the TCAC gives a new oxonium ion.
- Loss of water from this oxonium ion gives the ester and water
Examples
- The formation of benzocaine.