Dr. Hofmann on Chloranil. 203 



If the formulae of hydrate of phenyleand chloranil be com- 

 pared, the transit of the one into the other is at once per- 

 cciven* 



C,2H6O2 + 2O + 10CI = C„Cl4O4 + 6HCl. 



' , ' ' , ' 



Hydrate of phenyle. Chloranil. 



The foregoing equation gives the final result of the decom- 

 position ; but I must remark that another compound precedes 

 the formation of the chloranil. If the process be interrupted 

 when the hydrate of phenyle becomes somewhat glutinous, a 

 solid crystalline mass will result upon cooling, in which the 

 chloranil is enveloped by a red, tenacious, disagreeably-smell- 

 ing resin, dissolving in every proportion in alcohol, and this 

 property allows of its easy separation from the former. When 

 the alcoholic solution of the resinous mass is submitted to di- 

 stillation, what remains in the retort becomes fluid as soon as 

 the spirit has passed off, and along with the abundant disen- 

 gagement of hydrochloric acid there distils over a heavy red 

 oil, which sometimes solidifies in the receiver, charcoal re- 

 maining in the retort. 



The distillate obtained in this way dissolves in potash or 

 ammonia. Such a solution not containing an excess of the 

 alkali, gives with copper and silver salts the purple, violet and 

 yellow precipitates, characteristic of chlorophenissicand chlo- 

 rophenussic acids. 



The circumstances under which the acid had formed made 

 it probable that it was chlorinated chlorindoptic acid (chloro- 

 phenussic acid), particularly as it appeared collaterally with 

 chloranil in the method originally followed by Erdmann. It 

 might however have been chlorophenissic, or else a mixture 

 of the two acids. 



To solve this question, I decomposed the filtered potash 

 compound of the distillate with sulphuric acid, and obtained 

 a feebly-coloured precipitate, which was collected on a filter, 

 edulcorated, desiccated, and in order to remove the last traces 

 of water, fused at a low temperature. By the distillation of 

 this dry mass, a thick colourless oil condensed in the receiver, 

 and also in the lower portion of the neck of the retort, which 

 became a solid mass of a crystalline structure, possessing, with 

 the exception of the odour, the greatest resemblance to stearic 

 acid. 



Determination of the chlorine in this compound : — 

 0-5229grm. of substance ignited with lime, &c., gave 1*1334) 

 grm. of chloride of silver = .53'4<7 per cent, chlorine. 



The preceding analysis shows the compound to be chloro- 

 phenissic acid Ci2 nf + HO = 53'51 per ct, chlorine, while 

 ' P2 



