Mr Crocker, On the formation of Di-nitro-phenoocazines. 345 



extremely soluble, and alcohol added to the solution, a chocolate- 

 brown crystalline precipitate was formed. These crystals contained 

 aniline, and when heated evolved aniline and then exploded. The 

 high melting-point (269°) suggested that condensation of the 

 phenol-body to the oxazine had taken place and this was proved 

 by the abundant presence of nitrite in the aniline liquors. More- 

 over, alcoholic potash gave no coloration in the cold, but when 

 heated the blue- violet of the oxazines was immediately apparent. 

 Owing to their extreme solubility in aniline, and the necessity 

 for using alcohol as precipitant, these crystals were not obtained 

 quite pure. The aniline found approached most nearly to two 

 molecules of aniline of crystallisation. After evaporation of the 

 aniline, the residual brown powder was crystallised from dilute 

 acetic acid. It was then obtained as a dark-bronze powder, m.p. 

 277°. Analysis gave results in accordance with picramido-di- 

 nitro-phenoxazine. 



•2115 gm. gave 370 c.c. N at 18*5° and 751 bar. pr. 



/NH . Pi 



° 6H3 \ N q/C 6 H 2 (N0 2 ) 2 



Nitrogen 20-04 19-68 



Attempts to get the oxazine direct from amidol only resulted 

 in a small yield of oxazine, which deposited first, and a good yield 

 of the phenol-body. Excess of KOH should be carefully avoided. 

 The use of alkaline sulphite in place of alkali makes the process 

 simpler and gives an excellent product, but the yield of the phenol- 

 body is not so good. It was not found possible to condense the 

 phenol-body by the use of strong alkalis like potash. Feebly 

 alkaline bodies, e.g. aniline or sodium phosphate, on the other 

 hand, usually cause the oxazine condensation. The following 

 method gave satisfactory results. 



4 gm. of the phenol-body were added to 350 c.c. alcohol and 

 heated on water-bath. 46 gm. of pulverised sodium phosphate 

 were gradually added while stirring. The substance dissolved 

 and minute bronze sheeny plates immediately settled out. The 

 substance, recrystallised from glacial acetic, consisted of minute 

 bronze-coloured plates, melting at 277°, which give the character- 

 istic oxazine reaction with potash. It was difficultly soluble in 

 alcohol, and fairly easily soluble in glacial acetic acid. The yield 

 of crude product was 3"5 gm. Analysis gave results in accordance 

 with picramido-di-nitro-phenoxazine 



/NH . Pi 



aH ^^> B H 2 (N0 2 ), 



