Illustrated Glossary of Organic Chemistry

Kolbe-Schmitt reaction (Kolbe process): A reaction for adding a carboxyl group onto the benzene ring of a phenol. Used for the industrial synthesis of salicylic acid to be converted into aspirin.

In this example of the Kolbe-Schmitt reaction, phenol is converted into salicylic acid.

The mechanism for the Kolbe-Schmitt reaction begins with deprotonation of phenol by hydroxide ion (a strong base) to give phenoxide (the conjugate base of phenol). Phenoxide (an alkoxide and enolate nucleophile) adds to carbon dioxide to give a carboxylate. Aqueous sulfuric acid (a strong acid) protonates the carboxylate. Acid-catalyzed tautomerization then restores aromaticity.