118 KEPOKTrf ON THE STATE OF SCIENCE. 



The viesvs expressed in last year's report are confirmed by these more 

 extended observations. The most simple interpretation of the facts seem 

 to b3 that the catalyst (the acid) and the nitroamine form an additive 

 compound, which alone is capable of molecular rearrangement. 



For what reason the speed of the transformation should be proportional 

 to the second power of the concentration of the acid is not very obvious. 

 Blanksma ^ observed that the rate of the analogous transformation of 

 ftcetylchloroaminobenzene into p-chloroacetanilide bore the same relation 

 to the concentration of the hydrogen chloride, which is the only catalytic 

 accelerator of this change. Acree ^ has suggested that the existence of 

 the additive compound of the chloroamine and the catalyst is conditioned 

 by the equilibrium : Ar.NClAc,HCl;l Ar. NCI. Ac + H' + CI', when the 

 concentration of the complex would depend on the square of the concen- 

 tration of the acid. That the ratios of the accelerating effects of hydro- 

 chloric, nitric, and sulphuric acids, A-hce : ^'hno, '• ^''h.so, = 1:1: 2/3, are 

 approximately in the ratio of their ionisation in normal solutions is in 

 harmony with this view. 



II. The Wandering of Bromine in the Transformation of Nilroamino- 



bromobenzenes. 



(With C. Pearson, B.Sc.) 



In the transformation of 2 : 6-dibromo-l-nitroaminobenzene, in all 

 circumstances •when such a change will take place, we have observed 

 a remarkable rearrangement of the points of attachment of the sub- 

 stituting groups. 



NH.. 



NH.NO., /- 



Not only is the normal product, 2 : 6-dibromo-4-nitroaniline, I, in 

 which the nitro group passes to the vacant para-position formed, but 

 also 2 : 4-dibromo-6-nitroaniline, II. In the production of the latter 

 compound, the migrating nitro group displaces one ortho -placed bromine 

 atom, which then becomes attached to the para carbon atom. 



The direct nitration of 2 ; 6-dibromoacetanilide is not accompanied 

 by any such rearrangement ; the nitro group only enters the para- 

 position. 



> Bccueildes Trav. CJiim., 1903, 22, 290. 

 ^ Amer. Cliem. Jour., 1907, 38, 258. 



