4 PROCEEDINGS OF THE AMERICAN ACADEMY. 



H 

 BrC - CO BrC - CH 2 



I I > 



BrC - CO BrC - CO 



II 



Toennies found that his product could be converted into mucobromic 

 acid by oxidation with chromic acid, and therefore considered it to be 

 the double aldehyde of dibromfumaric acid. We found, on the other 

 hand, that the body showed none of the ordinary characters of an al- 

 dehyde. On warming with chromic acid it was slowly oxidized, but 

 mucobromic acid was not formed in quantity sufficient to enable us to 

 identify it with precision. On long boiling with bromine and water 

 mucobromic acid was formed. From concentrated nitric acid it could 

 be recrystallized unchanged, and only after continued boiling was it 

 oxidized to mucobromic and dibrommaleic acids. It did not combine 

 with acid sodic sulphite, and did not react with hydroxylamine. Ani- 

 line in alcoholic solution removed one atom of bromine and gave a 

 phenylamido derivative of the form C 4 Il2(C 6 H 5 NH)BrOo, and phenyl- 

 hydrazine also removed bromine. Aqueous alkalies dissolved it with 

 the formation of a deep yellow solution, but decomposition soon ensued 

 with the elimination of hydrobromic acid. The whole behavior of the 

 body was in direct opposition to the assumption that it was a double 

 aldehyde, and the unsyinmetrical structure was further established by 

 the existence of two isomeric bodies of the same general constitution 

 which contained a single bromine atom. The conclusion was inevita- 

 ble that the body was a dibromcrotonolactone. The rigorous proof of 

 its lactone structure, through its conversion into a salt of the corre- 

 sponding oxy-ac:d was rendered difficult by the presence of the halogen 

 since the halogen itself was rapidly removed in alkaline solution. By 

 adding a decinormal solution of potassic hydrate to a cold dilute solu- 

 tion of the substance it is true that it was easy to prove that very 

 nearly two molecules of potassic hydrate were neutralized in the re- 

 action, while but one molecule of potassic bromide was formed, but it 

 was impossible to isolate definite products of the decomposition. On 

 reducing the body with zinc and dilute sulphuric acid the bromine 

 was completely removed, and on distillation a feebly acid solution was 

 obtained, which on titration with decinormal potassic hydrate proved 

 to contain a lactone. By the usual methods an amorphous barium 

 salt was obtained, which when thoroughly dried had the percentage 

 composition required by a baric oxycrotonate. The isolation of the 



