10 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



HC 



C1C = 



CBr 



X 



/ 



CC1 



HC- 



C1C 



CBr 2 



/ 

 CClBr 



HC - CBr, 



\ 



/ 

 C1C - CO 







The close relationship between mucobromic acid and bodies which 

 have thus been shown to be derivatives of crotonolactone naturally 

 recalled the suggestions which had already been made as to the constitu- 

 tion of mucobromic acid itself. As early as 1882 Roser* pointed out 

 that the so called fumaric aldehyde acid of Liinpricht might in reality 

 be an oxylactone, 



HC 



H 

 COH 



x O 



HC- CO 



and afterward in 1887 Anschiitz,t in his interesting and suggestive 

 discussion of the constitution of maleic and fumaric acids, was led 

 to the conclusion that mucobromic acid was an oxydibromcrotono- 

 lactone : 



H 

 BrC - COH 

 V 



/ 

 BrC - CO 



O 



It was evident that the almost quantitative reduction of mucobromyl- 

 bromide by such a reducing agent as stannous chloride in the cold was 

 perfectly intelligible if the formula of this bromide were 



BrC- 



BrC- 



H 

 CBr 



\ 



CO 



o 



while the formation of a lactone under these conditions from the 

 bromanhydride derived from the aldehyde acid 



BrC-C 



II 

 O 



BrC - COBr 



* Berichte d. deutsch. chem. Gesellsch., XV. 1523. 

 t Ann. Chem. u. Pharm., CCXXXIX. 161. 



