Flash Photolysis of Azo Dyes in Aqueous Solutions of Biacetyl

Irradiation by microsecond flash of aqueous aerobic solutions of biacetyl (2,3-butanedione) and a number of different azo dyes resulted in oxidative fading of the dyes. The fading kinetics of all tautomeric dyes could only be described properly by assuming three oxidative species. The first one believed to be singlet oxygen, the second an adduct of oxygen and triplet biacetyl, and the third derived from the second (could be an acylperoxy-radical). The non-tautomeric dye C.I. Acid Red 37 was recycled partially after very fast fading during the first 0.5 ms