JACKSON AND KOCH. — DERIVATIVES OF ORTHOBENZOQUINONE. 225 



The substance, therefore, is evidently formed by the union of two 

 molecules of the resorcine with one of the quinone with elimination of 

 two molecules of hydrobromic acid, and may be called the ditribrom- 

 metoxyphenyldibromortlioquinophenylene ether. 



Properties. — It crystallizes from benzol in slender lemon-yellow prisms 

 with square ends, and melts at 217°. It is soluble in ether; slightly 

 soluble in cold alcohol or chloroform, easily soluble in either of these 

 solvents when hot ; nearly insoluble in cold benzol, much more soluble in 

 hot benzol, which is the best solvent for it. It does not dissolve in sodic 

 hydrate, which throws some doubt on the formula we have ascribed to 

 it, as this contains two hydroxyl groups. 



Action of Glacial Acetic Acid on the Tetrabromorthoquinone. 



As has been already stated, tetrabromorthoquinone, when crystallized 

 from glacial acetic acid, is partially converted into a white substance * 

 which we found it convenient to prepare as follows: 10 grams of 

 tetrabromorthoquinone were dissolved in 80 c.c. of glacial acetic acid and 

 the solution slowly evaporated to dryness on the steam-bath, the reddish 

 white residue was moistened with 10 c.c. of glacial acetic, and the slow 

 evaporation on the steam-bath repeated, in order to act on any tetra- 

 bromorthoquinone which might have escaped the previous reaction ; the 

 residue was then extracted with 200 c.c. of hot alcohol, and filtered boiling, 

 when the red hexabromorthoquinopyrocatechine ether previously described 

 was left behind, as it is insoluble in alcohol. This substance seemed to 

 be a constant product of the reaction, but not a principal one, as the 

 amount was only about 0.8 gram. The alcoholic solution was allowed to 

 cool, and filtered again ; then it was diluted with 200 c.c. of water, which 

 precipitated out the white product, amounting to from 5-6 grams. 

 This was purified by crystallization from glacial acetic acid, until 

 it showed the constant melting point 230°, when it was dried at 100°, 

 and analyzed with the following results : — 



I. 0.2658 gram of the substance gave on combustion 0.1903 gram 



of carbonic dioxide and 0.0179 gram of water. 

 II. 0.1373 gram of the substance gave by the method of Carius 0.2306 

 gram of argentic bromide. 



* Zincke (Bcr. d. chem. Ges. XX. 1777) converted tetrabromorthoquinone into 

 a white substance by crystallizing it from a mixture of ether and ligroin. On re- 

 peating the experiment we did not succeed in finding the conditions under which 

 the white product is formed. 



VOL. XXXVI. — 15 



