Photoinitiated processes in 1-p-tolylsulfonylazo-2,4,6,8-tetrakis(tert-butyl)phenoxazine

New photochromic compound 1-p-tolylsulfonylazo-2,4,6,8-tetrakis(tert-butyl) phenoxazine containing the intramolecular hydrogen bond NH . . .N and the c orresponding model structures 2,4,6,8-tetrakis(tert-butyl)-1-(veratroylazo) phenoxazine and 2,4,6,8-tetrakis(tert-butyl)-N-acetyl-1-(p-tolylsulfonylazo )phenoxazine were synthesized and studied. The data obtained suggested the mechanism of the photoreaction resulting in the accumulation of betaine 1-h ydroxy-2,4,6,8-tetrakis(tert-butyl)-10-tolylsulfonylphenoxazin-9-one. The p hotochromic transformations in the molecule under study are due to intramol ecular proton phototransfer followed by E-Z-isomerization about the N-N bon d and the formation of betaine 1-hydroxy-2,4,6,8-tetrakis(tert-butyl)-10-to lylsulfonylphenoxazin-9-one. The molecular and crystal structure of the pho toproduct was studied by X-ray analysis.