Photosensitized Oxidation of Leuco-uranine. I. Qualitative Studies of the Nature of the Reaction in the Deaerated Solution

Abstract

Abstract The nature of the photosensitized oxidation of leuco-uranine (in the deaerated condition), using uranine or acridine as a sensitizer, was investigated from various viewpoints. The possibility of either an oxidizing or a reducing impurity taking part in the reaction was definitely ruled out. The uranine (Remark: Graphics omitted.) leucouranine reaction could be repeatedly carried out in the presence of palladium asbestos. When uranine was used as a sensitizer (alkaline solution), an appreciable quantity of semiquinone could be detected as an intermediate. Reexamination of the spectra of acridine (when acridine was used as a sensitizer) showed that in some cases acridine takes part in the eventual reaction. It is concluded from various pieces of indirect evidence that the overall reaction is the evolution of hydrogen gas from the leuco dyealthough the direct detection of hydrogen formation has yet been successful.