Photosensitized reduction of benzil by heteroatom-containing anthracene dyes

Benzil in methanol was quantitatively reduced to benzoin by triethylamine in the presence of some heteroatom-containing anthracene dyes under visible irradiation. The thermodynamics, kinetics, and various quantum yields were investigated. The transient intermediate of the reaction was detected by flash photolysis. The relationship between the photosensitized reduction and the fading of the dyes was studied. The requirements for the dyes and the mechanism of these reactions were clarified.