The syntheses of a new angular azaphenoxazine and of two new angular azaphenothiazine ring systems are described and the dyeing properties of their derivatives studied. Thiocyanation of 2-amino-6-picoline (8) followed by hydrolysis and condensation with 2,3-dichloro-1,4-naphthoquinone (11) gave the purple-coloured 6-chloro-10-methylbenzo[a]-11-azaphenothiazin-5-one (12) in excellent yields. Similarly, from 4,6-diaminopyrimidine (15) and 2-amino-3-pyridinol (22), the compounds, 8-amino-6-chlorobenzo[a]-9,11-diazaphenothiazin-5-one (18) and 6-chlorobenzo[a]-11-azaphenox-azin-5-one (23), were obtained as bluish-purple and orange colourants, respectively. Elemental analysis, infrared, ultraviolet, NMR and mass spectroscopy agree with the assigned tetracyclic structures. Reduction with Na2S2O4 and the ease of air oxidation of the reduced forms to the quinoid coloured materials make them applicable as vat dyes. Fastness to washing, light, acids and bases was also investigated, and also their toxicity in laboratory animals.
Dyes and Pigments 01/1987; 8(1):11-24. DOI:10.1016/0143-7208(87)85002-7