86 REPORTS ON THE STATE OF SCIENCE. 



nucleus shared, assuming an o- or p-quinonoid form (II). The sub- 

 stituting group wandered in this rearrangement into the o- or p- 

 position. Thus the rigid adherence of anilines and anilides to the 

 ortho-para law was accounted for. 



Subsequently Acree l adopted the formation of the complex as the 

 cause of the arrangement of chloroamines, and showed how, on this 

 assumption, the speed of the change is proportional to the square of 

 the concentration of hydrochloric acid, for the concentration of the 

 reactive complex is proportional to the square of the concentration of 

 the hydrogen chloride if it be ionised, thus : — 



Ar.NHAcCl 2 ^ Ar.NClAc + H - + CI'. 



The discovery (by Orton and Jones 2 ) that an equilibrium existed 

 between chloroamine, hydrogen chloride, anilide, and chlorine, thus: 

 K= [chloroamine] [HC1] / [anilide] [CI*] ; or, when the medium is 

 65 per cent, acetic acid, or more dilute 



K 1 = [chloroamine] [HC1] 2 / [anilide] [Cl 2 ], 



showed that other factors had to be taken into account. This 

 equilibrium may be represented thus: — 



Ar.NHAc + Cl 2 ^ complex ^> Ar.NClAc + HC1, 



a relation which has been stated by Acree as a possibility. The facts 

 of the case, however, do not appear to require in any way the existence 

 of such an intermediary. 



The discovery of the formation of free chlorine and anilide when 

 hydrogen chloride reacts with chloroamine has led us to a new in- 

 vestigation of the transformation of chloroamines, and of the process 

 of halogenation of anilides. 



The Caialyst. — A great difficulty in the way of the ' complex 

 hypothesis ' is the fact that hydrochloric acid alone has the power of 

 bringing about the isomeric change of the chloroamine. Acree believed 

 that other acids, and even chlorine and bromine, were similarly, but 

 less powerfully, effective. But although we have examined this point 

 very closely we have not been able to confirm his view. 



In dilute acetic acid, when no hydrochloric acid has been added, the 

 change of the chloroamine occurs at first slowly, but gathering speed. 

 Hydrogen chloride can always be detected. Thus in 65 per cent, 

 acetic acid after half the chloroamine (initial concentration 0'025 gram- 

 molecule per litre) has disappeared tV of the chlorine initially present 

 in the chloroamine is found as hydrogen chloride. 



The addition of sulphuric acid (nitric, perchloric, or hydrofluoric 

 acid) somewhat increases the rate of change, some 10 per cent, of 

 the chlorine appearing as hydrogen chloride during the first half of the 

 reaction. 



The action of halogens was tested in carbon tetrachloride solution. 

 (Obviously petroleum, which was used by Acree, is unsuitable for 

 such experiments.) "With acetanilide, chlorine reacts instantaneously 



1 Amer. Chem. Journ., 1907, 38, 258. 



2 Trans. Chem. Soc, 1909, 95, 14; Reports, 1909. 



