180 PROCEEDINGS OP THE AMERICAN ACADEMY 



When the original product of the reaction was treated at once 

 with dry chloroform, the greater part was instantly carried into solu- 

 tion ; and the dibromsuccinic acid, together with a small quantity of 

 mucobromic acid, were left undissolved. The filtered chloroform solu- 

 tion, when shaken with a few drops of water, gradually solidified with 

 separating crystals of dibrommaleic acid ; so that the original product 

 must have contained the dibrommaleic acid as anhydride. 



The two main products of the reaction were, therefore, dibrom- 

 maleic anhydride and mucobromylbromide. The relative weights of 

 these two products were such as to suggest at once the equation : — 



2 C.H^Br.Og + Br^ = C.H^Br^O, -f C.HBrgO^ + HBr, 



when the dibrommaleic acid would readily pass into its anhydride. 

 The weights obtained in successive preparations were, however, found 

 to vary so much that I am inclined to consider the anhydride as the 

 direct product of the reaction, and the mucobromylbromide a second- 

 ary product formed by the action of the hydrobromic acid set free. In 

 either case, the formation of dibromsuccinic acid can hardly be ex- 

 plained without assuming a reducing action of the hydrobromic acid, 

 like that which is normal to hydriodic acid. Although reductions of 

 this sort by the action of hydrobromic acid have seldom been noticed, 

 the conversion of tartaric acid into monobromsuccinic acid by this 

 means, noticed by Kekule* in 18G4, would seem to be perfectly analo- 

 gous. 



Dibrommaleic Acid of Kekule. 



In 1864 Kekule f found among the products of the action of bromine 

 and water upon succinic acid an acid, C^H2Br204, to which he gave 

 the name dibrommaleic acid. It formed white, clustered needles, 

 which were extremely soluble in water, alcohol, or ether, and melted 

 at 112° ; at higher temperatures the acid distilled apparently un- 

 changed, and it volatilized readily with steam. For the further 

 characterization of the acid, Kekule made the silver and lead salts. 

 The silver salt could be precipitated from an aqueous solution of the 

 acid, by the addition of argentic nitrate ; and, according to the concen- 

 tration of the solution, it appeared as a granular, crystalline precipi- 

 tate, or in slender, glistening needles. The dry salt exploded vio- 

 lently by heat or percussion. The lead salt was thrown down by the 



* Ann. Chem. u. Pliarm., cxxx. 30. 

 t Ann. Chem. u. Pnarm., cxxx. 1. 



