218 PROCEEDINGS OP THE AMERICAN ACADEMY 



Properties of Pyromucamide Tetrabromide. — It is a crystalline 

 solid without color or odor. Its melting point is about 121°, as 

 determined in the ordinary way, but it varies with the rapidity of 

 the heating. By long heating the substance will melt, always 

 with evident decomposition, even below 100°. It is insoluble in 

 water, almost insoluble in ether, chloroform, glacial acetic acid, or 

 alcohol, somewhat more readily soluble in ethyl acetate and ace- 

 tone. It is decomposed by boiling with water, alcohol, or glacial 

 acetic acid. When it was dissolved in alcohol and treated with 

 zinc dust in the cold, the bromine was abstracted and pyromuca- 

 mide formed. On boiling with water it is decomposed; hydro- 

 bromic acid is formed, but no definite organic compound could be 

 isolated. In order to study the products formed by the action of 

 alkalies, the tetrabromide was added gradually, in small portions, 

 to cold concentrated alcoholic sodium hydroxide. After standing 

 in the cold for about an hour, the mixture was allowed to remain 

 for several days in a warm room, the alcohol being renewed when 

 necessary. Ammonia was slowly evolved. The alcohol was then 

 evaporated off, and the solid residue treated with water. Only a 

 very small portion of insoluble matter was left. This was filtered 

 off. On acidifying the filtrate, an acid was precipitated which was 

 purified by converting it into the barium salt, and separating the 

 latter by fractional crystallization into three portions. The acid 

 was then liberated from each portion separately. It appeared to 

 be /3y-dibrompyromucic acid, since each fraction melted at about 

 192°, the purest at 191°. 5. To remove all doubt, this portion was 

 dissolved in absolute alcohol, and converted into the ethyl ester 

 by the action of dry hydrochloric acid. The observed melting 

 point of the ester, 67°. 5, completed the proof as to the nature of 

 the acid, since the /3-y-dibrompyromucic acid melts at 191-192°, 

 and its ethyl ester at 67-68° .* /38-dibronipyromucic acid does not 

 seem to be formed at all in this decomposition of pyromucamide 

 tetrabromide. Even microscopic examination failed to prove its 

 presence, though the crystals are quite characteristic. This is 

 interesting in consideration of the fact observed by Hill and San- 

 ger,* that the tetrabromide of pyromucic acid yields, under similar 

 circumstances, a mixture of the two isomeric dibrompyromucic acids 

 (/3yand/3S). 



* These Proceedings, XXI. 155 el seq. 



