98 Proceedings of the Royal Irish Academy. 



where doubt existed we have deemed it necessary to prepare, in a pure 

 condition, some of the more important of these nitro derivatives in a manner 

 which would leave no doubt as to their constitutions. 



We have, in addition, attempted the preparation of some hitherto unknown 

 nitro derivatives of diphenylamine in the hope that a study of their properties 

 may enable us to detect them if present, even in small quantities, amongst 

 the substances formed by the action of nitric acid, at low temperatures and 

 concentrations, on diphenylamine. 



The various methods which have been recommended for coupling aromatic 

 amines with the halogen derivatives of aromatic nitro bodies have been 

 examined by us, ami we have found that in general the best results are 

 got by the method of lima Goldberg (D.RP. 185663, 1*7870; cf. Ber. d. 

 Dtsch. Chcm. Gea \1 < 1907), pp. 4541-4546), in which a nitrobenzene solution 

 of the components is heated foi Beveral hours with anhydrous potassium 

 carbonate and cuprous iodide, or traces of copper and potassium iodide. 

 In this way we obtained 4- and 3-nitro-diphenylamines which had been 

 previously prepared by I. Goldberg I and the hitherto unknown 



3.10-dinitro-diphenylamine, but attempts to prepare 3.9-dinitro-dipheny- 

 lamine by this method were unsuccessful 



2.4.8.10-Tetauu'tro-diphenylamine, which frequently occurs amongst the 

 nitration products ol diphenylamine, had not been previously obtained In- 

 direct coupling of a nitro-amine with the halogen derivative of an aromatic 

 nitro-body. We obtained it by Goldberg's method from 2.4-dinitro-aniline 

 and 2.4-dinitro-bromo-benzene, a synthesis which removes any doubt that 

 may hi. 1 as to the constitution "f the compound. We did not, 



however, Bucceed in effecting tin- combination of picryl chloride ami 

 2.4-dinitro-aniline, by which we hoped to effect a synthtsisof 2.4.6.8.10-penta- 

 nitro-diphenylami 



Although basic amines, such as aniline, combine easily with the nitro- 

 derivatives of bromo-benzene, nitro-derivatives of the aminos do not interact 

 so easily with nitro-derivatives of the halogen compound, and in some cases 

 we were unable to isolate any pure product of the reaction. Since, in some 

 cases, it has been observed that a nitro group may be replaced by an amine 

 residue more easily than a halogen atom, we examined the behaviour 

 of /3- and y-trinitro-toluenes in reactions such as those we were studying. 



y-Trinitro-toluene i> y in alcoholic solution with m- and 



p-nitranilines forming well-crystallised derivatives of 5-methyl-diphenylamine, 

 andasmall amount of a crystalline product Conned hy the action of /3-trinitro- 

 toluene on m-nitraniline is probably derived from the same base. 



We also examined the action of the oxyacids of nitrogen on some nitro- 



