The formation of semiquinones of eosin, erythrosin and Bengal rose was detected spectrally in the reaction of photoreduction of these dyes in organic solvents: pyridine and ethanol. 2.  The absorption spectra of semiquinones of eosin, erythrosin and Bengal rose were determined and their concentrations were estimated. The maximum concentration of eosin semiquinone at the temperature of –35° reaches 40% of the initial dye concentration. 3.  The kinetic curves of change of the electrode potential immersed in the illuminated solution describe the process of formation and consumption of the semiquinones of the dyes during the photoreduction reaction. 4.  A scheme for the photoreduction reaction was suggested and the rate constants of the eosin semiquinone reactions were evaluated.

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change of the electrode potential bengal rose semiquinone photoreduction reaction absorption spectra kinetic curves semiquinones of eosin erythrosin

V. F. TsepalovV. Ya. Shlyapintokh,.Mechanism of the photoreduction of xanthene dyes. 8 (4),611-616.

V. F. TsepalovV. Ya. Shlyapintokh,"Mechanism of the photoreduction of xanthene dyes" 8

V. F. TsepalovV. Ya. Shlyapintokh,"Mechanism of the photoreduction of xanthene dyes"