Studies of the Photoreduction of Thiazine Dyes in Aqueous Solutions

Abstract
Judging from the experiments performed in our laboratory, the photoreduction of dye without the addition of any reducing agent takes place only in thiazine dyes, and the reaction is particularly prominent when demethylation occurs simultaneously. The reaction proceeds in the following way: D+hν→D* D*Dt Dt+D→X (X=D−……D+) (Remark: Graphics omitted.) The part in parentheses is still doubtful. The above conclusion is consistent with the results of the flash experiment which will be described in a following paper. It has been proposed that some reducing agents attack Dt directly, while others attack the half-oxidized state.