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Chemistry LibreTexts

17.21 How Chemists Activate Carboxylic Acids

Carboxylic acids react with Thionyl Chloride (\(SOCl_2\)) to form acid chlorides. During the reaction the hydroxyl group of the carboxylic acid is converted to a chlorosulfite intermediate making it a better leaving group. The chloride anion produced during the reaction acts a nucleophile.

General Reaction

 

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Example

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Mechanism

1) Nucleophilic attack on Thionyl Chloride

 

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2) Removal of Cl leaving group

 

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3) Nucleophilic attack on the carbonyl

 

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4) Leaving group removal

 

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5) Deprotonation

 

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Contributors

Prof. Steven Farmer (Sonoma State University)