Pechmann Reaction

Pechmann condensation discovered by Hans von Pechmann in 1883 is condensation of phenols with β-keto esters or carboxylic acids under acidic conditions to form coumarins. The acid catalysts used for the Pechmann condensation reaction are concentrated sulphuric acid, trifluoroacetic acid (TFA), phosphotungstic acid, TiCl₄, P₂O₅, ZrCl₄, Nafion resin, HClO₄/SiO₂, SnCl₂·2H₂O, zirconium phosphor-tungstate, deep eutectic solvents, ionic liquids, etc.

Mechanism of Pechmann Reaction