Rvan and Ryan — Action of Acids on Diphenylamine. 197 



only one case (Expt.4) have we, as yet, heen aide to isolate the (race of nilio 

 gamines formed (luring the reactions. In addition to the brown resinous body 

 which is not, as has been assumed, a brmitro-diphenylamine, the chief products 

 are 240-dinitro-, 4'10-dinitro-, and 2 , 4 , 8 , 10-tetranitro-diphenylamines. 



On the other hand, when one equivalent of nitrous acid is present, the 

 first product is the nearly colourless diphenylnitrosamine which can be readily 

 recognized by the deep-blue colouration it gives with sulphuric, even in the 

 absence of nitric, acid. The nitric acid acts upon the compound, producing 

 first an orange-yellow solution from which the nearly colourless 4-nitro- 

 diphenylnitrosamine can be, without difficulty, isolated. It is probable that 

 the orange- yellow colour of the solution is due to small amounts of 2-nitro- 

 diphenyl amine and 2-nitro-diphenylnitrosamine, which we have not, however, 

 isolated. 



In the next stage the main product is the sparingly soluble, yellowish- 

 white, 2 - 10-dinitro-diphenylnitrosamine, which separates from the system and 

 undergoes no further change. 



The dissolved portion, which also contains 4iO-dinitro-diphenylamine or 

 its nitroso derivative, is finally converted into the pale-yellow 2 - 4'8T0- 

 tetranitro-diphenylamine, the colour of the solution changing slowly from 

 orange-yellow to pale-yellow, and in these cases never becoming green, brown, 

 or red. 



It has been generally, but incorrectly, assumed (V. Buisson, he. cit.) 

 that the order of formation of the compound is 4-nitro-nitroso-, 4-nitro-, 

 2"4-dinitro-, and finally 2 - 4"6-trinitro-diphenylamine. In no one of our 

 experiments were there any indications of the formation of the easily recog- 

 nizable s2'4-dinitro- or 2 - 4 - 6-trinitro-diphenylamine. The main product is in 

 every case, where nitrous acid is also present, a dinitro-diphenylnitrosamine, 

 and at present we regard the formation of this compound as indicating the 

 completion of the stabilizing action of the diphenylamine. 



In the qualitative tests now employed technically for the detection of 

 diphenylamine derivatives the dinitro-nitrose, trinitro-, and tetranitro- 

 diphenylamines, which are very sparingly soluble in hot alcohol, remain in 

 the powder in the first stage of the tests. The examination of these and also 

 of the quantitative tests will be undertaken at a later period. 



There is little doubt that the dinitro-diphenylnitrosamine interferes with 

 the heat tests at 110° or 135 C C, and may interfere even with the Abel test. 

 Although the presence of this compound in a powder may not atl'ect the rate of 

 deterioration, there is no doubt that a heat test at 135 c C. will indicate a lower 

 degree of stability of the powder, owing to the loss of nitric oxide from the 

 nitrosamine group, than magazine storage under normal conditions will show. 



B.I. A. PROC, VOL. XXXIV, SECT. 13. [2 L>~\ 



