Uyan & O'TooLK — Action of Oxides, Sfc, on the Phenytureas. 145 



two, four, and six molecular amounts of nitric acid, the urea was unattacked even 

 on allowing to remain at the room temperature for prolonged periods. 



In carbon tetrachloride suspension, however, the substances reacted. With one 

 two, and four molecular parts of nitric acid 4'4'-dinitro-s-diphenylurea was formed, 

 as well as traces of 4-nitro-s-diphenylurea, melting at 212° C. [Leuekart J. f . pr. 

 chem. (2), 41, 322]. With six molecular amounts of nitric acid, 2-4'2'-4'-tetranitro- 

 s-diphenylurea was obtained as well as 4'4'-dinitro-s-diphenylurea. 



By the action of nitrous acid (from aqueous hydrochloric acid and sodium 

 nitrite) on s-diphenylurea, dissolved in a mixture of acetone and ether, a substance 

 was formed at room temperature, which on partial evaporation of the solvents 

 separated as cream-coloured prismatic needles decomposing at 103° C. The amounts 

 of the urea and nitrous acid or the proportion of acetone to ether were not 

 observed in this experiment, and various attempts to repeat it under observed 

 conditions in acetone-ether solution failed. The compound was not formed in ether 

 or acetone. It was finally obtained in glacial acetic acid solution with two or more 

 molecular parts of nitrous acid. The compound was dinitroso-s-diphenylurea, 

 which was also formed by the action of nitrous fumes and nitrogen peroxide on 

 s-diphenylurea in glacial acetic acid solution. 



The direct nitration of dinitroso-s-diphenylurea was also carried out, and 

 2-4-2'-4'-tetranitro-s-diphenylurea was obtained in this way. Nitrated in the 

 presence of acetic acid at low concentrations and at ordinary room temperatures 

 it yielded, on long standing, 4'4'-dinitro-s-diphenylnrea as a main product. 



k— ACTION OF NITROUS FUMUS ON SYMMETRICAL DIPHENYLUREA. 



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

 nitrous fumes were passed into the mixture for three quarters of an hour. The 

 diphenylurea dissolved with simultaneous separation of another substance in the 

 form of cream-coloured needles. The mixture was allowed to remain in a stoppered 

 flask at the temperature of the room for thirty-six hours. It was then 

 filtered, and the residue was washed with water and dried. It decomposed 

 about 100° C. 



On addition of water to the filtrate a further quantity of the same compound 

 was obtained. By dissolving it in hot ether, and allowing most of the ether to 

 evaporate, it was obtained as prismatic needles, wliich decomposed with evolution 

 of gas at 103° C. 



Analysis of this substance gave the following results : — 



(a) 01327 g. of the substance gave 23'5 c.c. of moist nitrogen at 18° 0. 



and 762 mm., 



which corresponded to N 20'51. 



(b) 0'1103 g. of the substance gave 19'3 c.c. of moist nitrogen at 17° 0. 



and 766 mm., 



which corresponded to N 20'o3. 

 C,3Hi„03N4 required N 20 ^^ 



On boiling with alcohol for some time it gave s-diphenylurea. It was therefore 

 dinitroso-s-diphenylurea. 



Dinitro-s-diphenylurea is a nearly colourless substance, which crystallises in 

 prismatic needles. It is decomposed by hot water, and dissolves in most organic 

 solvents. 



