Photosensitized Oxidation of Leuco-uranine and the Identification of the Photobleached Product of Uranine in Ethanol Solution

Abstract

Abstract Leuco-uranine was prepared by reducing uranine with sodium amalgam, and some of its properties were investigated. The aqueous solution of leuco-uranine is stable in the presence of air irrespective of its low oxidationreduction potential. It was found that leuco-uranine is photooxidized to uranine by the use of acridine and some dyes as sensitizers. The reaction may be attributed to the dissolved oxygen and is very reasonable. A quite unexpected result was, however, that a similar reaction takes place more rapidly and more quantitatively in the degassed solution than in the aerated solution. The uranine and acridine employed as sensitizers in this case were ascertained not to sustain any change. The nature of the reaction is not known at the present time. It was further established that the photobleached product obtained by irradiating the deaerated ethanol solution of xanthene dyes, consists mainly of leuco dye. This was ascertained by comparing their absorption spectra, by the photosensitized coloration, acridine being used as a sensitizer, and, in addition, by means of paper chromatography.