1871.] Bromine-substitution Compounds of the Orcins* 73 



Cklororcin. 



Pentachlororcin, C 7 H 3 Cl g 2 . — This compound was obtained by the 

 action of chlorine upon orciu when the former was kept in excess. Two 

 methods of effecting this object were employed, — the first by adding the 

 orcin to chlorine hydrate, the other by the action of potassium chlorate 

 and hydrochloric acid. 



A pulpy mixture of the crystalline hydrate of chlorine and water was 

 first prepared by passing a current of chlorine, with occasional agitation, 

 through water to which about one third of crushed ice had been added, 

 until a sufficient quantity of the hydrate was formed. On gradually add- 

 ing a moderately strong aqueous solution of orcin, a purple colour was 

 produced when the solution first came in contact with the chlorine hydrate, 

 but disappeared immediately on agitation. The addition of the orcin was 

 continued until nearly all the chlorine hydrate was decomposed. It was 

 always advisable to leave a slight excess of the latter, as a purer product 

 was then obtained, and also to have some crushed ice present in the mixture, 

 to avoid decomposition and consequent loss of the hydrate by the heat 

 produced during the reaction. The colourless or pale yellow solution, 

 on standing, yielded a crystalline deposit of crude pentachlororcin. 



After many trials, however, it was found that pentachlororcin could 

 generally be more conveniently prepared in quantity by submitting orcin 

 to the chlorinating action of a mixture of hydrochloric acid and potassium 

 chlorate in the following manner : — Four parts of powdered potassium 

 chlorate and a solution of two parts of orcin in seven parts of hydrochloric 

 acid were added to 35 parts of hydrochloric acid, sp. gr. 1*17, placed in a 

 large beaker, and kept cool by immersion in water ; a small portion of the 

 potassium chlorate was first added to the hydrochloric acid in the beaker ; 

 on pouring in some of the solution of orcin, the same evanescent purple 

 colour made its appearance as when chlorine hydrate was used ; the alter- 

 nate addition of the chlorate and the orcin solution was continued in such 

 a manner that there might always be an excess of chlorate, and that the 

 contents of the beaker never became very hot. It was found necessary to 

 use concentrated hydrochloric acid in this experiment, as otherwise the 

 product was largely contaminated with a viscid oily compound. After 

 twelve to twenty hours the crystalline chlororcin was collected and washed 

 with a small quantity of water. Orcin treated with chlorine hydrate yields 

 nearly twice its weight of crude chlororcin, but with potassium chlorate and 

 hydrochloric acid about 150 per cent, of its weight. 



In order to purify the crude chlororcin obtained by either of the above- 

 described methods, it was dissolved when dry in a considerable quantity of 

 carbon disulphide (eight measures), filtered and concentrated by distillation 

 (to one half). On being set aside for some time it usually crystallized 

 out ; but as it exhibits strongly the phenomenon of supersaturation, espe- 

 cially when impure, it was sometimes necessary to agitate or add a crystal 



