Phenoxazine nitration

Phenoxazine-1,9-dicarboxylie acid, 2-amino-4,6-dimethyI-3-oxo-occurrence, 3, 1037 Phenoxazines arylation, 3, 1011 electrophilic reactions, 3, 1012 nitration, 3, 1012 nomenclature, 3, 996 oxidation, 3, 1010 reactions, 3, 1011 structure, 2, 4, 7-8 3, 1010 synthesis, 3, 1033... 

Starting from phenoxazine, the leuco 47 is obtained through a multistep reaction involving nitration, reduction, and acylation.6... 

Even the comparatively unreactive phenoxazine and phenothiazine systems undergo halogenation and nitration with ease and it is normal to prepare monosubstituted derivatives by stepwise procedures rather than by direct electrophilic attack. Indeed, the nitration of phenoxazine is uncontrollable and even N-acylphenoxazines afford a mixture of di- and tetra-nitro products (03CB475). Similarly phenothiazine and nitric acid produce a complex mixture of nitrated sulfoxides and sulfones. Chlorine in DMSO at 40 °C reacts with phenothiazine to yield 3,7-dichlorophenothiazine, whereas cupric chloride gives the 1,7-isomer (76JPR353). Direct bromination of phenoxazine produces a mixture of 3-bromo- and 3,7-dibromo-phenoxazines, while thionyl chloride affords the 1,3,7,9-tetrachloro derivative (60ZOB1893). 

Phenoxazine itself reacts very violently even with dilute nitric acid to give tetranitrophenoxazine (25, X = N02) and no mono or dinitro derivatives.64 V-Acetylphenoxazine, however, is nitrated in acetic acid to give a mononitro-A-acetylphenoxazine,26 which after deacetylation proved to be identical with 3-nitrophenoxazine (23, X = N02), obtained by the Turpin reaction (see Section II, A, 2). On nitration in acetic anhydride A-acetylphenoxazine yielded a mixture of 25 (X = N02) and the acetyl derivative of 24 (X = N02). 

Dodecyl acrylate microspheres, crosslinked with hexanediol diacrylate, were prepared by emulsion polymerisation and characterised by scanning electron microscopy, particle size measurement, and differential scanning calorimetry. The microspheres were doped with 9-(diethylamino)-5-(octadecanoylimino)-5H-benzo(alpha)phenoxazine (ETH 5294), a chromoionophore whose fluorescence emission spectrum is sensitive to pH. These microspheres adsorb anions selectively according to their lipophilicity, and therefore can be used as anion-selective optical sensors. The responses of the microspheres to chloride, nitrate and perchlorate ions were reported. 27 refs. 

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