Contribution of singlet oxygen to the accelerated decolorizing of dye mixtures

Binary mixtures of dispersed dyes, which during irradiation with polychromatic light give an effect of accelerated decolorization, were studied. Quantum yields of the formation of singlet oxygen by individual dyes were estimated during irradiation of solutions in ethyl acetate with light of 435 and 546 nm as well as quantum yields of the reaction of dyes with singlet oxygen. It was found that the contribution of the reaction of dyes with singlet oxygen to the effects of accelerated decolorization were vanishingly small. The quantum yield of the photodestruction of dyes in a mixture was 10^–3-10^–5 and the quantum yield of reaction with singlet oxygen was less than 10^–6. It was concluded that accelerated decolorization of the systems studied is not determined by reaction with singlet oxygen.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2014–2017, September, 1991.