Chinon-Amin-Reaktionen, 12. Mitt. Synthese und Farbe von Naphthothiazinonen

Quinone-Amine Reactions, XII: Synthesis and Colour of Naphthothiazinones Because of NH/S exchange, naphthothiazinones 8 absorb visible light with a maximum that is shifted towards shorter wavelengths, relative to that of corresponding benzoquinoxalinones 3 , by 10 nm in neutral and by 20 nm in acidic solution. This hypsochromic shift is smaller than for NH/NAc exchange in 4 . Thiazinones 8 are synthetized from naphthoquinones 1 and cysteamin (5) .