Ozone Fading of Phenolphthalein and Aurin

The reactions of phenolphthalein, which exist as a lactone-quinonoid tautomeric mixture in solution, and aurin with ozone have been examined. The reactivity of the lactone tautomer of phenolphthalein with ozone was found to be low and the azone attacks the aromatic ring. In the case of aurin ozone also attacks the carbon skeleton