118 Scientific Proceedings, Royal Dublin Society. 



-E,.— ATTEMPTS TO SYNTHESISE THE NITBO-DIPHENYLURETHANES. 



(1) A small quantity of 4-nitro-diphenylurethaiie (0-5 gram) was dissolved in 

 xylene, and the solution heated with 0'5 gram of ehloroformic ester in a sealed 

 tube at 160° C. for eight hours. The excess of ehloroformic ester and the xylene 

 were then distilled off, and the residue crystallised from alcohol, from which it 

 separated in the form of yellow leaves, melting at 133°-134° C, and which proved 

 to be the original solid — 4-nitro-diphenylamine. 



(2) Equal quantities of 4-nitro-diphenylamine (1 gram) and ehloroformic ester 

 were heated with a little alcohol in a sealed tube at 160^ C. for ten hours. In 

 this experiment also the 4-nitro-diphenylamine was recovered unchanged. 



(3) In another experiment some 2-10-dinitro-diphenylamine was dissolved in 

 xylene, and excess of ehloroformic ester was added to the solution, which was 

 then heated to boiling under a reflux condenser for ten hours. In this case also 

 the solid recovered proved to be the original 2-10-dinitro-diphenylamine. 



(4) Equal quantities of symmetrical tetranitro-diphenylamiiie and ehloro- 

 formic ester were heated in a sealed tube at 1 80° 0. for eight hours. Large 

 yellow crystals were formed, which on recrystallisation from xylene melted at 

 199° C, and were therefore the original solid recovered unchanged. 



Summary. 



1. Nitric acid at the ordinary temperature and at low concentrations in acetic- 

 acid solution had apparently no action on diphenylurethane. 



Under similar conditions in carbon tetrachloride solution, nitric acid converted 

 the urethane into its 4-nitro, 4-10-dinitro, and 2'10-dinitro derivatives. 



2. Cold concentrated nitric acid (sp. g. 1-42) converted the urethane into its 

 4-nitro derivative, while fuming nitric acid under similar conditions formed a 

 mixture of the 4- 10- and the 2'10-dinitro-diphenylurethanes. 



3. The urethane, or its 4-nitro derivative, was nitrated by a mixture of con- 

 centrated nitric and sulphuric acids into 2-4'8'10-tetranitro-diphenylurethane, 

 and the latter reacted further with the hot mixed nitrating acids forming 

 2'4'6"8'10'12-hexanitro-diphenylamine. 



4. Nitrogen peroxide reacted with diphenylurethane in carbon tetrachloride 

 solution with the formation of the 4'10- and the 2"10-dinitro derivatives of the 

 urethane. 



5. Notwithstanding the similarity in structure between diphenyluiethane- 

 and diphenylnitrosamine, the former substance reacts with nitric acid much 

 less readily than the latter, the nitration at low temperatures and concentrations 

 stopping at the dinitro stage. 



In conclusion we wish to state that the above research was undertaken at the 

 request of the Eesearch Section of Nobel's Explosives Company, to whom we are 

 indebted for a grant in aid of the investigation. 



