220 PROCEEDINGS OF THE AMERICAN ACADEMY. 



ni 



69.49 



Properties of Hexabromorthoquinopyrocatechine Ether. — The sub- 

 stance crystallizes from warm uitrobenzol in short slender prisms of a 

 pure vermilion red color ; it does not melt, and is insoluble in all the 

 common solvents ; nitrobenzol dissolves it especially when warm, but, if 

 the solution is heated above 100^, decomposition sets in, as shown by a 

 change of color. The ordinary strong acids have no effect on it in the 

 cold, but fuming nitric acid dissolves it with decomposition ; alkalies do 

 not dissolve it, but the substance turns black after standing with an alkali 

 for a short time. The red color of the substance indicates that it con- 

 tains two orthoquinone oxygen atoms, and this view is confirmed by its 

 behavior with hydrochloric acid and reducing agents described later. 



The red substance is probably formed from tetrabrompyrocatechine 

 and tetrabromorthoquinone by the following reaction : — 



CaBr4(OH)2+C6Br40,-C6Br,0,C6Br202+2HBr. 



To test this a new preparation was made as described above, and, after 

 the mixture had stood twenty-four hours, it was diluted with five times 

 its volume of water, the reddish white precipitate formed filtered out, the 

 aqueous filtrate acidified with nitric acid, and treated with argentic nitrate, 

 when a heavy precipitate of argentic bromide was thrown down, showing 

 the presence of hj^irobromic acid among the products of the reaction. It 

 was also found that the best yield was obtained when the two reagents 

 were used in the proportion of equal molecules, as required by the reac- 

 tion. The best solvent to be used in the preparation was glacial acetic 

 acid and water, as already described, but the red body was also formed 

 in dilute alcohol (the proportions used were 0.5 gram of each reagent, 

 40 c.c. of alcohol, and 10 c.c. of water). On the other hand, no reaction 

 was observed when the solvent was ether or chloroform. One gram of 

 each of the reagents was dissolved in 50 c.c. of ether (care was taken 

 that the substances were free from even a trace of acetic acid), and 

 allowed to stand twenty-four hours. As no precipitate had formed, the 

 ether was allowed to evaporate spontaneously, when a reddish white res- 

 idue was left, which looked like a mixture of the unaltered reagents, and 

 dissolved completely in hot chloroform. This showed that none of the 

 hexabromorthoquinopyrocatechine ether had been formed, as it is insolu- 



