Ryan and Ryan — Action of Acids on Diphenylaminc. 203 



The yellowish-white solids which had separated from the acetic acid 

 solutions of diphenylnitrosaniine containing two, three, four, and six equiva- 

 lents of nitric acid were all identical. The solids were washed with cold 

 chloroform, which removed some of the colouring matter (melting at 125- 

 145° C), the residual solid then melting with decomposition at 156-159° C. 

 This substance turned orange-yellow when heated on the water-bath, and in 

 trying to purify it by crystallization from hot solvents the colour became 

 much more intense, and the melting-point, which rose considerably, became 

 much less sharp. After several attempts to purify a portion of it by crys- 

 tallization from alcohol, chloroform, and glacial acetic acid we finally obtained 

 the cinnabar red 2-10-dinitro-dipJicni/laminc, melting at 219° C. of 0. X. Witt 

 (Ber. d. dtsch. chem. Ges. xi (1878), p. 758), with a smaller amount of a 

 lighter-coloured, lower-melting (175-205° C), impure substance. 



It was evident, therefore, that we were dealing with a very unstable 

 nitro-nitroso derivative, and we found in fact that when 0-9 gram of the 

 substance was dissolved in 30 c.es. of boiling xylene, and heated under a 

 reilux condenser for two hours, it split off oxides of nitrogen, which appeared 

 as brown fumes in the reflux condenser, and turned iodized starch paper 

 blue. The dark-red xylene solution was distilled, and the residue, which 

 consisted almost entirely of 2'lQ-dinitro-diphcnylaminc, after recrystallization 

 from glacial acetic acid melted at 219° C. 



The nearly white parent substance was, therefore, 2T0 dinitrodiplmvyl- 

 nitrosamine. 



It gave on analysis the following results : — 



0'1896 gram substance gave 32 c.cs. of nitrogen 

 at 19° C. and 766 m.m.p. 



corresponding to N 19'50. 



C 12 H 9 N 4 5 requires N 194. 



2T0 dinitrodiphe'iiylnitrosamine consists of nearly colourless crystals 

 which are sparingly soluble in cold organic solvents, and are coloured dark 

 orange in contact with concentrated sulphuric acid. 



C. — Action of Nitric Acid on i-Nitro-Dipfa nylnitrosamine. 



Four grams of 4-nitro-diphenylnitrosamine were dissolved in a cold 

 mixture of 6 c.cs. (6 mols.) of nitric acid (sp. gr. 1'43) and 200 c.cs. of 

 glacial acetic acid. The solution was let remain in a stoppered flask at the 

 temperature of the laboratory for two weeks. After twenty-four hours a 

 yellowish-white solid began to separate, and the colour of the solution, which 

 was at first orange-yellow, gradually changed to yellow. 



