664. TRANSACTIONS OF SECTION B. 



considerable time in a dry atmosphere, although it is not a very stable body. Itie 

 comparatively safe to handle, and promises to be of considerable use as a synthetic 

 agent, as it is easily soluble in water, alcohol, and ether, and is very reactive. 

 Its composition shows that it has the formula CONoH.^Clj, and having regard to 

 its mode of formation as well as to the structure of urea itself, its constitution is 



most probably represented by the formula OC^i^Tipi' 



By means of this formula its formation and such of its reactions as have yet 

 been studied can be explained. The other theoretically possible chloro substi- 

 tution derivatives of urea, though probably formed in the reaction between 

 chlorine and urea, have not so far been isolated. 



AVhen dichloro urea is produced, although two molecules of hydrogen chloride 

 are formed, very little heat is developed, and it must therefore be an endothermic 

 compound and might be expected to be highly explosive. When heated, how- 

 ever, it does not itself explode, but decomposes at about 83°, with liberation of 

 nitrogen chloride, which latter may detonate with great violence if not allowed 

 to escape, and if the temperature is raised a few degrees higher, as, for example, 

 when dichloro urea is heated in a test tube over a water-bath. 



Dichloro urea gives all the characteristic reactions of a typical nitrogen 

 chloride; for instance, it liberates iodine from hydriodic acid, chlorine from 

 hydrochloric acid, and reacts with alcohol, forming ethyl hypochlorite, urea being 

 in each case re-formed. 



Dichloro urea is distinguished from most other substituted nitrogen chlorides 

 by the readiness with which it is hydrolysed, nitrogen chloride, carbon dioxide, 

 a little nitrogen, and ammonium chloride being formed. If the compound is dis- 

 solved in water or kept in a moist atmosphere, this hydrolysis takes place slowly 

 at the ordinary temperature, and becomes very rapid at about 30° C. 



It is probable that in this reaction a mono-substituted ammonia is first pro- 

 duced thus; — 



''KnHCI + ^^^^^ = <^'0<^0H -^ ^^^fi^- 



But if so, it apparently can only exist momentarily, as nitrogen chloride is at 

 once liberated. The formation of the end-products of the reaction can be 

 explained by assuming that this monochloro ammonia immediately breaks up 

 into ammonia and nitrogen chloride. 



3NH.,Cl = 2NH., + NCi„ 



which then to some extent react in the ordinary way, forming nitrogen and 

 hydrogen chloride, the latter at once combining with the free ammonia and 

 allowing the remaining nitrogen chloride to escape, as this does not react with 

 ammonium chloride. 



Both acids and alkalis accelerate the rate of hydi'olysis, and further alter the 

 rature of the end-products by hindering or furthering the secondary reaction 

 between the ammonia and the nitrogen chloride. In presence of dilute acids the 

 ammonia is at once fixed, and the reaction between it and the nitrogen chloride, 

 with its accompanying liberation of nitrogen, is prevented; all the chlorine con- 

 tained in the dichloro urea is therefore liberated as nitrogen chloride. In presence 

 of allialis, on the other hand, the reaction between the ammonia and the nitrogen 

 chloride goes on to completion since the hydrochloric acid formed in it is at once 

 iixed ; no nitrogen chloride, therefore, is set free since twice as much ammonia as 

 is required to decompose it is present. 



The leaction between dichloro urea and a solution of caustic potash is very 

 energetic ; nitrogen is liberated with effervescence, the excess of ammonia and the 

 alkaline carbonate formed remaining dissolved in the liquid. The action, which is 

 fjuantitative, is expressed by the equation 



IHCl 



•a 



-fj^j + 1 2K0H = 3K5CO, + 2NH3 + 6KC1 + 2N., + 6H,,0, 



