218 PROCEEDINGS OF THE AMERICAN ACADEMY. 



and, as a comparison of the two substances showed th< \ crystallized in 

 the same form, there cau be no doubt of their identity. The formation 

 of a paraquinone derivative from our orthoquinoue has been already 

 explained in the introduction to this paper. 



In the hope of obtaining a phenazine the solution of orlhoquinone was 

 treated with orthophenylene diamine j a reaction took place, the principal 

 products of which consisted of uninviting black Bubstances and pyrocate- 

 chine recognized by the formation of its lead salt. From the appearance 

 of the pyrocatechine we inferred that the reaction consisted principally 

 in the oxidation of the diamine by the orthoquinoue, and as even after 

 trying the experiment under several varying conditions no more prom- 

 ising results were obtained, this line of work was abandoned. Phenol 

 also gave with the solution of orthoquinoue such an uninviting product 

 that we did not attempt to study it. Sodic hydrate gives with the ortho- 

 quinoue solution a green coloration similar to that obtained by the action 

 of sodic hydrate on tetrabromorthoquinone. 



Dkrivatives of Tktrabromorthobenzoquinone. 



f 



The tetrabromorthoquinone used in this work was prepared as follows: 

 20 grams of pyrocatechine were dissolved in CO c.c. of glacial acetic 

 acid, and 37 c.c. of bromine added gradually from a burette. The mix- 

 ture was allowed to stand over night, after which the product was puri- 

 fied by recrystallization from 200 c.c. of glacial acetic acid. In this way 

 forty grams of pyrocatechine yielded 118-12G grains of reervstallized 

 tetrabrompyrocatechine ; that is, between 7o and 80 per cent of the theo- 

 retical yield. To convert this tetrabrompyrocatechine into tetrabrom- 

 orthoquinone thirty grams of it were dissolved in 300 c.c. of glacial acetic 

 acid by heating on the water-bath ; the solution was then cooled to 16°, 

 or until the glacial acetic acid began to solidify, and eleven grams of 

 fuming nitric- acid of Bpecific gravity 1..") diluted with 60 c.c. of glacial 

 acetic acid added rapidly, the mixture being kept cool and stirred vig- 

 isly during the addition; after Btanding for five minutes 300 c.c. of 

 water were added, and stirred in thoroughly. If the process had run 

 successfully, the tetrabromorthoquinone settled to the bottom in a glis- 

 tening mass of dark red crystals, which were filtered off) and dried. The 

 product thus obtained melted at 1 !•'» -l 17 instead of 150° 151°, but 

 was pure enough for our work, which was fortunate, as recrystallization 

 from glacial acetic acid is attended In a great loss ,,f material. Thirty 

 grams of tetrabrompyrocatechine gave eighteen grams of tetrabromortho- 

 quinone, which amounts to about 60 per cent of the theoretical yield. 



