TRANSACTIONS QF SECTION B. 



663 



under tbe influence of the acid undergoes the intramolecukr rearrangement 

 characteristic of these compounds, whereby the halogen passes into the para or 

 ortho position in the nucleus. Mono and disubstituted hydrazines are thus pro- 

 duced — for example : 



NBr.NHoHBr 



NH.NH.HBr NBr.NH,HBr NH.NH,.HBr 



Br 



Further substitution into the remaining ortho position has not been observed, 

 and probably cannot be effected, since the substitution of halogen so lessens the 

 basicity of the hydrazine that the NH„ group is attacked by preference ; indeed 

 the yield of mono or disubstituted hydrazine is never satisfactory, diazonium salts 

 and their decomposition products always being produced in large quantity. 



Tlie author has recently shown ^ that when the required amounts of bromine are 

 added to aromatic hydrazines dissolved in acetic acid, diazonium perbromides, 

 which are thus N-trlbromosubstituted hydrazines, are produced quantitatively. 

 The replacement of hydrogen in the -NH.NHg group can thus be carried to com- 

 pletion — for example : 



C.H.-N-H 



H-N-H 



C,F,-N-H 



I 

 • Br-N-H 



C„H,-N-Br 



I 

 Br-N-H 



Cn -N-Br 



Br-N-Br 



Each of these substitution products can undergo the typical diazo decomposition 

 quantitatively when the conditions are favourable. Thus by the action of bromine 

 upon phenyl hydrazine we can obtain either benzene or bromobenzene, nitrogeu 

 and hydrogen bromide or bromine being eliminated thus : — 



C.H, 



■N- 



I 



•N- 



H 

 Br 



C,H,-N 



I 

 Br-N 



Br C,B, -N-Br 



H 



Br-N- Br. 



Other compounds besides these simple ones may be formed — for example, from 

 among the products of the action of bromine on phenyl hydrazine, in addition to 

 benzene and bromobenzene, p- and m-dibromobenzene and 1, 2, 4 and 1, 3, 5 tri- 

 bromobenzene have been isolated, as well as azobenzene and dipheuyl ; the forrna- 

 tion of all these products can be simply explained by the theory of the reaction 

 here put forward. It is, moreover, entirely in harmony with all that has been 

 observed iu the oxidation of the aromatic hydrazines. 



7. Some ReacfAons of Dichloro Urea. 

 By F. D. Chattaway, B.Sc, F.B.S. 



Urea is so well huown and has been so much investigated that any new simple 

 substance obtainable from it possesses quite an unusual amount of interest. Such 

 a new substance is found in dichloro urea, which, leaving out of consideration 

 the derivatives of ammonia itself, is one of the simplest possible compounds con- 

 taining halogen attached to nitrogen. It is produced when chlorine is passed 

 into a cooled saturated aqueous solution of urea. Action takes place without 

 any considerable development of heat, and dichloro urea crystallises out as a 

 white powder consisting of small transparent plates. It can be preserved for a 



» Prpe, Client- Soc„ 1908, 24, 172, 



