JACKSON AND KOCH. — DERIVATIVES OF ORTHOBENZOQUINONE. 221 



ble in chloroform. Another portion of the residue from the ethereal 

 solution was dissolved in glacial acetic acid, and slightly diluted, when a 

 copious deposit of the red body appeared on standing. The fact that we 

 observed no action when the tetrabromorthoquinone and tetrabrompyro- 

 catechine were mixed in ether is strange, since Zincke* states that by the 

 action of these two bodies in ether or benzol he obtained black shiuiucr 

 needles, which changed color at 1 10° and sintered together to a brownish 

 liquid. We are unable to explain this difference in the results of the 

 experiments, but hope that future work may lead us to the conditions 

 necessary for preparing the black substance. 



If the substance is formed by the reaction given above, it is probable 

 that the two benzol rings are connected by two of the atoms of oxygen ; 

 but this is not necessarily the case, as the product might also be a deriv- 

 ative of diphenyl, in which both rings contain orthoquinone groups. To 

 settle the mode of union of the two benzol rings, we submitted the sub- 

 stance to reduction with sodium amalgam as follows : Ten grams of the 

 red substance were covered with water in a flask, from which all the air 

 was excluded by a stream of carbonic dioxide, 3 per cent sodium amal- 

 gam was then added in large excess, and the reaction was allowed to 

 run at ordinary temperatures in the atmosphere of carbonic dioxide for 

 several days. At the end of this time the red substance had been con- 

 verted principally into a purplish white body, which seemed to resist the 

 further action of the sodium amalgam ; it was, therefore, filtered out, and 

 washed with dilute acid and alcohol ; the aqueous filtrate from this sub- 

 stance gave no precipitate on acidification, but on subsequent extraction 

 with ether we obtained from the extract a considerable quantity of a white 

 residue, which after several crystallizations from benzol gave the melting 

 point 100° instead of 104°, the true melting point of pyrocatechine ; from 

 the form of its crystals, however, and as it gave the lead salt and the 

 characteristic color with ferric chloride, there can be no doubt that it was 

 pyrocatechine. As has been stated, the principal product of this reduc- 

 tion was the purplish white insoluble substance, the weight of which 

 amounted to 6 grams from 10 grams of the red body; it was obvious, 

 therefore, that no safe inference in regard to the constitution of the red 

 substance could be drawn from the appearance of this small proportion 

 of pyrocatechine. Accordingly, in the hope of increasing our yield of 

 pyrocatechine, this purplish white product was submitted to reduction 

 with sodium amalgam under the conditions used in its formation, the 



* Eer. d. chem. Ges., XX. 1778. 



