Constitution of the Diazoamido- Compounds. 527 



A few remarks may here be made in connexion with the 

 transformation of diazoamido- into amidoazo-compounds. It 

 has always been supposed hitherto that this transformation is 

 preceded by a resolution of the diazoamido-compound into its 

 constituents *. This may be the case in the presence of excess 

 of acid ; but it is doubtful whether such a resolution occurs 

 when the diazoamido-compound (say diazoamidobenzene) is 

 allowed to stand in the presence of excess of aniline containing 

 only a small quantity of aniline hydrochloride. It is well known, 

 however, that such a mixture will effect the complete conver- 

 sion of diazoamido- into amidoazobenzene in the course of a 

 few hours, especially if aided by heat. If the formula of 

 diazoamidobenzene is written according to the present view, 

 it will be seen that a slight rearrangement of the " bonds " 

 would convert it into a symmetrical compound of the type 

 already proposed for the mixed diazoamido-compounds ; 

 thus : — 



N:N N:N- 



OT.C fi H, 



C fi H, 



It seems not improbable that such a symmetrical compound 

 may precede the formation of amidoazobenzene, the separation 

 (accompanied by the migration of the H-atom to the NH- 

 group)f occurring along one of the dotted lines. 



Although the formulae now proposed for the normal diazo- 

 amido-compounds appear capable of meeting all the require- 

 ments of the case, it will be of interest to point out that other 

 molecular arrangements in which phenyl functions as a tri- 

 atomic radical are possible : — 



JS T .NH.X /N v w JvTH 



<j X C > T <I *o 



I. II. III. 



* See the last contribution to this question by TVallach {Lieb. Ann. 

 vol. ccxxxv. p. 238). I am bound to express the "opinion, however, that 

 the suggestion there thrown out does not materially add to the solution 

 of the problem (Proc. Ohem. Soc. 1887, p. 27). 



t Such a transference of hydrogen is analogous to that which takes 

 place whenhydrazobenzene, C R H 5 . NH . NH . C 6 H,, is converted into ben- 

 zidine, NH 2 . C 6 H 4 .C B H 4 . NH 2 , by the action of acids. No previous 

 resolution into constituents has ever been supposed in this case. The 

 transformation appears rather to be of the nature of a rotation of the ben- 

 zene rings, and there is reason for believing that a similar rotation takes 

 place in the decomposition of mixed dinzoamido-compounds by acids. 

 This point cannot be discussed, however, until the evidence is more 

 complete. 



