220 PROCEEDINGS OF THE AMERICAN ACADEMY. 



111 



G9.49 



Properties of BexabromorthoquinopyroccU/echine Ether. — The sub- 

 Btance crystallizes from warm nitrobenzol in Bhort slender prisms of a 

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

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

 the solution is beau- 1 above LOO . decomposition sets in, as shown by a 

 cbange of color. The ordinary strong acids have no effect on it iu 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 thai it con- 

 tains two orthoquinone oxygen atoms, ami 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 : — 



( , r.r 1 OII) 2 +C c B.^O,=C c Br 4 : ,C c Br 2 2 +2IIBr. 



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

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

 it- 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 hydrobromic acid among the products of the reaction. It 

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

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

 tion. The besl Bolventto be used in the preparation was glacial acetic 

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

 iii dilute alcohol (the proportions used were "."' .'ram of each reagent, 

 40 r.r. of alcohol, and 1<> <\c. of water). On the Other hand, no reaction 



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

 each of the reagents was dissolved in 50 <■■>•. of ether (care was taken 



that the Substances wen: free from even a trace of BCBtic acid i. and 



allowed to Btand twenty-four hours. As do 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 



»lved completely in bol chloroform. This showed that none of the 

 hexabromorthoquinopyrocateohine ether had been formed) as it is insola- 



