Ryan & O'Toolk — Action of Oxides, ^-c, on the Phenylureas. 151 



The solutions in the bottles to which four and six parts of nitric acid had been 

 added were filtered from the red solids. The latter, after removal of the oily 

 matter with cold glacial acetic acid, yielded in each case a red substance 

 (M.P. 170°-19U" C), from which no crystalline substance was obtained. The 

 carbon tetrachloride solutions were neutralized with barium carbonate, filtered, 

 and evaporated. In each case a black oil was obtained. In both cases there was 

 much free nitric acid present. 



II. — In the Absence of Solvents. 



5 g. of as-diphenylurea were added in small quantities to twelve molecular parts 

 of nitric acid cooled in salt and ice. The urea dissolved, giving a red solution. 

 On allowing the mixture to remain at room temperature overnight, a gas was 

 slowly evolved, and a yellow solid separated as prisms. This, when recrystallised 

 from glacial acetic acid, yielded yellow leaves melting at 200° C. It was 2-4-2''4'- 

 tetranitro-diphenylamine, as the addition of the latter substance to it did not affect 

 its melting point. A further quantity of this substance was obtained from the 

 nitric acid solution. 



^.—ACTION OF NITROUS ACID ON AS-DIPHENYLUREA. 

 One, two, four, and six molecular parts of sodium nitrite dissolved in a small 

 amount of water were added to 5 g. of as-diphenylurea in 100 g. of glacial acetic 

 acid in the cold. The mixtures were allowed to remain at room temperature for 

 fourteen days, when all the urea was recovered unchanged. 



4. — Triphenylueea. 



The action of the oxides of nitrogen on triphenylurea has not been previously 

 examined. Triphenylurea in glacial acetic acid solution reacted easily with both 

 nitrous fumes and nitrogen peroxide, givingin each case the same trinitro-triphenyl- 

 urea. The constitution of this substance was not detennined. 



Eeudler (loc. cit.) nitrated triphenylurea in the cold, and obtained a product 

 which gave no nitramine reactions. He obtained from it, after boiling with 

 alcohol, 2'4'2''4'-tetranitro-diphenylamine and 2-4-dinitro-phenylurethane. By 

 using larger excess of nitric acid he obtained 2"4'2'4'-tetranitro-diphenylamineand 

 2'4'6-trinitro-phenylurethane. In a similar experiment we only isolated 2'4'2''4'- 

 tetranitro-diphenylamine. 



Triphenylurea was nitrated for long periods at room temperature and at low 

 concentrations in acetic acid solution and in carbon tetrachloride suspension. 



In acetic acid solution with one and three molecular amounts of nitric acid the 

 urea was recovered unchanged ; with six and nine molecular parts, however, a 

 dinitro- and the trinitro-triphenylurea were formed in both cases. 



In carbon tetrachloride suspension, with one molecular amount of nitric acid, 

 the dinitro-triphenylurea was formed ; with three and six amounts the dinitro- as 

 well as the trinitro-triphenylurea was obtained ; and wiih nine amounts a 

 pentanitro-triphenylurea was formed. 



Nitrous acid was without action on triphenylurea in acetic acid solution even 

 on prolonged standing. 



A.— ACTION OF NITROUS FUMES ON TRIPHENYLUREA. 



•') g. of triphenylurea were dissolved in 100 g. of glacial acetic acid, and nitrous 

 fumes (from arsenious acid and nitric acid) passed into saturation at room tempera- 

 ture. The mixture was allowed to stand for a week at ordinary room temperature, 



