Photodecarboxylation of chromone-2-carboxylic acid in aerated and deaerated ethanol solution

Abstract The typical photodecarboxylation of chromone-2-carboxylic acid occurs in aerated and deaerated ethanol solutions to afford 4-hydroxycoumarin and 2-(1′-hydroxyethyl)-chromone, respectively. The former proceeds through an addition of the ground state oxygen molecule, while the latter through the recombination between the ketyl radical and the 1-hydroxyethyl radical followed by the release of CO 2 . Chemiluminescence technique was successfully applied to detect ketohydroperoxide intermediates assumed in the photoreaction of the aerated system.