200 Dr. Hofmann on Chloranil. 



crystalline body free from hydrogen, to which he gave the 

 name chloranih This substance, remarkable on account of 

 the series of interesting transformations which it undergoes 

 when in contact with the alkalies, has been diligently studied 

 by Erdmann. From his experiments, the composition of 

 chloranil is represented by the formula — 



Cg CI2 Og. 



This body has lately become the starting-point of some inter- 

 esting discussions, which Laurent* brought before the Aca- 

 demy at Paris. The view of this chemist assumes the equiva- 

 lent of chloranil to be double, agreeing with the formula, — 

 C,, CI, O4. 

 The method which Erdmann employed for obtaining chlo- 

 ranil is circuitous, and yields very little of that substance. He 

 passed a stream of chlorine gas through an alcoholic solution 

 of chlorisatin or bichlorisatin. The following equation repre- 

 sents the transformation of the chlorisatin into chloranil: — 



C16 { ci' } NO4 + 80 + 4C1 = Ci, CI4 O4 + 4CO2 + NH3 + HCl. 



. ' > ^-7-^ 



Chlorisatin. Chloranil. 



The process is not, however, so simple, as there is formed 

 at the same time chlorinated chlorindoptic acid (Laurent's 

 chlorophenussic acidf), as well as many other secondary pro- 

 ducts, and there is obtained a comparatively small quantity 

 only of chloranil. 



Somewhat later chloranil was re-observed under other cir- 

 cumstances. Fritzche J found, in some experiments upon the 

 blue colour assumed by aniline from the action of the oxygen 

 compounds of chlorine, that by a continued digestion of a 

 mixture of chlorate of potash and hydrochloric acid upon ani- 

 line, chloranil is also formed. 



I have had the opportunity, in a research upon the organic 

 bases of coal-gas naphtha§, to confirm this statement; the 

 whole of the carbon of the aniline enters into the chloranil, as 

 the following equation shows : — 



C„ H7 N, 40 -f 8Cl = C„ H4 O4 + NH3 + 4HCI. 



' V ' " » ' 



Aniline. Chloranil. 



The close relation subsisting between the aniline and phe- 

 nyle series induced me to try whether chloranil could not 

 be obtained from different members of this group of bo- 

 dies. I soon learnt that chloranil is often formed, as the 

 last product of decomposition of organic bodies, under the 



* Comptes Rendus, t. xix. No. 6. S. 31 6. 



t Aim. de Chem. et de Phys., Sine ser. t. iii. p. 498. [Phil. Mag. S. 3. 

 vol. xix. p. 191.] 



t Bidlet. Sclent, de St. Petersb., 1843, t. i. p. 103. 



$ Philosophical Magazine, Third Series, vol. xxiv. p. 199. 



