154 Scientific Proceedings^ Royal Dublin Society. 



with evolution of brown fumes, and melted with decomposition at 235°-236° C. 

 (uncorr.). An analysis of this substance gave the following result : — 



0'1237 g. of the substance gave 20 c.c. of moist nitrogen at 16° C. and 763 mm., 

 corresponding to N 18"92. 

 Ci9H„(JuN, required N 19-11. 



The substance was therefore a pentanitro-triphenylurea. 



Pentanitro-triphenylurea is a light yellow substance, and as obtained above 

 crystallises in prisms. It is sparingly soluble in most organic solvents, but soluble 

 in hot nitro-benzene. 



No solid was obtained either from the carbon tetrachloride or from the acetic 

 acid solution. 



I. — In the Absence of Solvents. 



5 g. of triphenylurea was added slowly to twelve molecular parts of nitric acid 

 cooled in salt and ice. The interaction was at first very violent, but towards the 

 end became more moderated. The triphenylurea dissolved, giving a red solution. 

 The mixture was allowed to remain overnight at the temperature of the room. On 

 pouring into much water an oily, yellow substance was obtained. This was filtered, 

 and the solid was well extracted with hot acetene and alcohol. A small quantity 

 of a yellow substance remained undissolved. This crystallised from glacial acetic 

 acid as leaves, meltiug at 200° C. (uncorr.). This substance was therefore similar 

 to 2'4'2'"4'-tetranitro-diphenylamine in melting point and crystalline form. The 

 addition of 2-4'2''4' tetranitro-diphenylamine to it had no effect upon its melting 

 point. Is was therefore 2-4-2'-4'-tetiranitro-diphenylamine. 



N"o other pure substance was isolated from the nitration product. 



D.— ACTION OF NITROUS ACID ON TRlPHIiNYLUREA. 



Triphenylurea (5 g.) was dissolved in 100 g. of glacial acetic acid and treated in 

 the cold with one, two, four, and six molecular parts of sodium nitrite, dissolved 

 in the smallest amount of water. The mixtures were allowed to remain at room 

 temperature for a fortnight. Yellow colourations were developed in all cases, but 

 the triphenylurea was recovered unchanged. 



Summary. 



1. The action of nitric acid on substituted ureas at the ordinary temperature 

 and at low concentrations was examined. 



Phenylurea formed phenylurea nitrate ; sym- and as-diphenylureas were 

 unacted upon ; and triphenylurea yielded a di- and a trinitro-triphenylurea. 



Under similar conditions, but in carbon tetrachloride suspension, phenylurea 

 formed its nitrate, its p-nitro, and its 2'4-dinitro derivatives. %m-diphenylurea 

 was nitrated to its 4-nitro, its 4-4'-dinitro, and its 2-4-2'-4'-tetranitro derivatives, 

 but ffis-diphenylurea yielded substances from which no pure compound was obtained. 

 Triphenylurea formed a mono-, a tri-, and a pentanitro-triphenylurea. 



2. Cold fuming nitric acid acted upon all four of the substituted ureas. 

 Phenylurea gave 2-4-dinitro-phenyl-nitro-urea ; sj/m-diphenylurea formed its 

 4'4'-dinitro and its 2-4-2'-4'-tetranitro derivatives; and from as-diphenylurea as 

 well as from triphenylurea 2-4'2'-4'-tetranitro-diphenylamine was obtained. 



