Abstract
Lumichrome which was formed by the photolysis of riboflavin in the presence of hydrogen peroxide in neutral or weak acidic medium, was decomposed in sealed tube with alkali to 3,4-dihydro-3-keto-6,7-dimethyl-2-quinoxaline carboxylic acid (lumiflavin-keto acid). By standing lumiflavin-keto acid at room temperature in alkaline solution in the presence of hydrogen peroxide, it is formed a bluish violet substance having Rf 0.80,which was proved to be 6,7-dimethyl-2,3-dioxotetrahydroquinoxaline. Lumiflavin-keto acid was transformed by sublimation at 250-270℃ to 3,4-dihydro-3-ketcr6,7-dimethylquinoxaline. The last compound was converted by methylation in alkaline solution by dimethyl sulfate to 3,4-dihydro-3-keto-4,6,7-trimethylquinoxaline.
