II. and P. Ryan — Action of Nitric Acid and Nitrous Acid. 213 



of the presence of other nitro-diphenylamines in some of the fractions which 

 we were unable to resolve into their components. 



The colour changes during the nitrations were from colourless to green or 

 to brownish-red in the case of amine, and to orange-yellow or light yellow in 

 the case of the nitrosamine. 



Owing to the ease with which the nitroso group may be split off' from nitro- 

 diphenylnitrosamines, we deemed it advisable to examine the behaviour of 

 nitric acid towards diphenylamine and diphenylnitrosamine in an inert 

 solvent such as carbon tetrachloride. 



The latter solvent is, however, in some respects not so suitable a medium 

 for nitrations as glacial acetic acid. When the nitric acid (sp. g. 15, was 

 added to the carbon tetrachloride solution of the amine or its nitrosamine 

 two layers formed, and the relative concentrations of the interacting 

 substances were, of course, different in the two layers, and in neither layer 

 did it correspond to the relative concentration of the interacting substance 

 for the system as a whole. 



Hence, although in acetic acid solution equi-molecular quantities of nitric 

 acid and diphenylnitrosamine formed only mononitro-diphenylnitrosamines, in 

 addition to these substances, both dinitro-diphenylamine and mononitro- 

 diphenylainine were obtained in carbon tetrachloride solution. 



Differences in the solubilities of the lower nitro and nitro-nitroso 

 derivatives in the two solvents, together with the decomposing action exercised 

 by the acetic acid on the dissolved nitro-nitroso compounds, affected the 

 results, but, generally speaking, the nitrations followed similar courses in the 

 two solvents. 



In the experiments, described below, on the action of nitric acid on 

 diphenylamine in carbon tetrachloride solution we obtained, in addition to 

 the resinous oxidation product referred to in our previous communication, 

 diphenylnitrosamine, 2.8- and 2.10-dinitro-diphenylamine, and somewhat 

 impure 2.10-dinitro-diphenylnitrosamine. From the corresponding experi- 

 ments with diphenylnitrosamine wegot 4-nitro-diphenylnitrosamine, 4-nilro- 

 diphenylarnine, 2.8-, 2. 10-, and 4.10-dinitro-diphenylamine, somewhat impure 

 '2-tO-dinitro-diphenylnitrosamine, 2.4.8-trinitro-diphenylamine, and 2.4.8.10- 

 tetranitro-diphenylamine. 



Combining the results of the nitrations in the two different solvents, the 

 course of the reaction between nitric acid, nitrous acid, and diphenylamine at 

 the ordinary temperature and at low concentrations of the interacting 

 substances may be represented by the following scheme : — 



2 F 2 



