146 Scientific Proceedings^ Royal Dublin Society. 



B— ACTION OF NITROGEN PEROXIDE ON SYMMETRICAL 

 DIP HEN YL UREA . 



(ft) s-Diphenylurea (2-5 g.) was well shaken with 100 g. of glacial acetic acid, 

 and nitrogen peroxide was passed into the mixture. The urea dissolved, whilst 

 another substance was seen to take its place. After some time the mixture was 

 filtered. The residue was washed with water, and on drj'ing decomposed at 

 102°-103°C. The addition of dinitroso-s-dipheuylurea to this substance did not 

 affect its decomposition point. Hence it was dinitroso-s-diphenylurea. From the 

 filtrate a further quantity of this substance was obtained. 



(&) As before, 2-5 g. of s-diphenylurea in 100 g. of glacial acetic acid was 

 treated with nitrogen peroxide, when dinitroso-s-diphenylurea was seen to be 

 formed. On further treatment with nitrogen peroxide this dissolved slowly, giving 

 a red solution, and on allowing the latter to remain in a stoppered flask at the 

 temperature of the room for five days a yellow solid slowly separated. 



The mixture was filtered, and the residue was well washed with alcohol, when 

 a yellow substance remained, melting with decomposition at .305°-315'' C. This, on 

 crystallisation from nitro -benzene, gave minute needles, decomposing at 320° C. 

 From the filtrate no pure substance was obtained. 



An analysis of the above-mentioned substance gave the following result : — • 



0'1032 g. of the substance gave 1645 c.c. of moist nitrogen at 18° C. 

 and 767 mm., 



corresponding to N 18'58. 

 O13H10O5N4 required N 18-54. 



This compound was also obtained by heating two molecular weights of 

 p-uitraniline with one of urea for five hours at 190° C, and was therefore 4'4'- 

 dinitro-s-diphenylurea. 



4'4'-dinitro-s-diphenylurea is a bright yellow compound, sparingly soluble in 

 most organic solvents, but soluble in hot nitro-benzene, from which it separates 

 on cooling as minute yellow needles. 



C— ACTION OF NITRIC ACID ON SYMMETRICAL DIPHENYLUREA. 



I. — In the Presence of Solvents. 



(a) Glacial acetic acid. — s-Diphenylurea - (2'5 g.) was treated in 200 g. of 

 glacial acetic acid with one, two, four, and six molecular parts of nitric acid in the 

 cold, and allowed to remain at the temperature of the room for two months. In the 

 case of one, two, and four parts of the acid no reaction was found to have taken 

 place, but in that with six parts of nitric acid a compound melting with decom- 

 position at 320° C. (probably 4'4'-dinitro-s-diphenlyurea) and one melting with 

 decomposition at 218° C. (probably 4-nitro-s-diphenylurea) were found. In this 

 case, however, it had been found necessary, during the two months, to warm the 

 bottle to melt the glacial acetic acid, which solidified several times. 



This nitration was repeated without heating, and no reaction was found to take 

 place. 



(b) Alcohol. — s-Diphenylurea (2-5 g.) with 150 c.c. of alcohol were treated in 

 the cold with one, two, four, and six molecular parts of nitric acid and allowed to 

 remain at room temperature for two months, when in every ease all the urea was 

 recovered unchanged. 



(c) Carlon tetrachloride. — s-Diphenylurea (2"5 g.) was suspended in 200 c.c. of 

 carbon tetrachloride, and treated in the cold with one, two, four, and six molecular 



