TRANSFORM At ION OP AROMATIC ttlTROAMINES, ETC. D? 



On the other hand, in acetic acid of high concentration, 90 to 100 

 per cent., the rate of change of the complex into chlorine and anilidc 

 must be much faster than into chlorinated anilide : — 



Ar.NHAcC] 2 



^t* ClAr.NHAc + HCl 



7^-* CL+Ar.NHAcJ 

 fast 



for the rate of C-chlorination is the same whether the system is made 

 up from chloroamine and hydrogen chloride or from chlorine and 

 anilide. 



(iv) The complex formed from acetanilide may be compared with 

 that formed from p-chloroacetanilide. Since the speed of chlorination 

 of acetanilide is very much greater (200 times in glacial acetic acid) 

 than that of p-chloroacetanilide, the rate of formation of the complex 

 from acetanilide and of its transformation are the more rapid. Never- 

 theless in dilute acetic acid, 50 per cent., the rats of conversion of 

 acetylchloroaminobenzene (fci=0'00039) is slower than that of acetyl- 

 chloroamino-p-chlorobenzene (fc l = 0'00053); hence it must be assumed 

 that the complex is produced at a slower rate from hydrogen chloride 

 and acetylchloroaminobenzene, or, what would have the same effect, 

 its concentration is very much smaller than in the case of p-chloro- 

 acetanilide. Moreover, the contrast is emphasised by the fact that the 

 speed of chlorination of acetanilide by the chloroamine of p-chloro- 

 acetanilide is relatively high. Here it must be assumed that the very 

 fast formation (and rearrangement) of the compound of acetanilide 

 and chlorine, the latter being set free by the reactions 



J^U CL.CJI3 NHAc + HC1 



2>-Cl.C (j H 1 .NClAc + HCl -> Cl.CJ^NHAcC)., 



~^-* Cl.C,H 4 .NHAc + CI , 



keep the concentration of the compound, Cl.C 6 H 4 .NHAcCL, at vanish- 

 ing point and thus prevent the formation of 2 :4-dichloroacetanilide. 



Alternative Hypothesis. Direct Action of Halogen on Anilide 

 or on a Dynamic Isomeride. 



It may well be asked whether the facts of chlorination and the 

 transformation of the chloroamines require for their interpretation the 

 assumption of the existence of a complex with many-sided characters 

 and capable of undergoing an intramolecular rearrangement in which 

 the wandering group is a chlorine atom. 



The specific part played by the hydrogen chloride in the transforma- 

 tion of the chloroamine, and the fact that this reagent causes the 

 production of chlorine and anilide, and the results of numerous experi- 

 ments, which may be summarised in the statement — whenever chlorine 

 and anilide are present at maximum concentration the speed of chlorina- 

 tion is highest — are more, or at least as, simply accounted for by direct 

 interaction of chlorine and anilide. 



An example may be found in the relation between the rate of con- 

 version of the chloroamine and the concentration of the hydrogen 



1910. h 



