8 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



xc = 



CBr 

 \ 



HC 



cx 



xc- 



+ Br, = 



CBr 2 

 \ 



HC- 



- CXBr 



a body is formed which through the action of water yields the deriva- 

 tive of maleic acid : 



XC - CBr„ 



\ 



XC 



O + H 2 

 HC - CXBr 



CO 

 \ 



O + 2IIBr 

 / 



HC - CXBr 



This in its turn gives the lactone by reduction : 



XC-CO 



x o 



/ 

 HC - CH 2 



In the case of the /38-dibrompyromucic acid the tribromfurfuran, 

 which should appear as the intermediate product in this reaction, has 

 been isolated in a pure condition by Mr. W. M. Booth in this Labora- 

 tory, and been found to yield, when treated with bromine in aqueous 

 solution, the brommaleylbromide described by Hill and Sanger. 



The a-bromcrotonolactone may also be formed by the action of 

 bromine in aqueous solution upon /3-brompyromucic acid. The reaction 

 is evidently identical with that through which the dibromcrotonolac- 

 tone is formed from /?y-dibrompyromucic acid. A dibromfurfuran is 

 first formed, which by the fixation of water and the elimination of 

 hydrobromic acid passes into the lactone : 



BrC = C - COOH 

 + Br 2 



BrC = 



HC 



O 

 / 



CH 



CBr 



\ 



HC = 



/ 

 CH 



O + C0 2 + HBr 



BrC = 



HC 



CBr 



X 

 / 



CH 



+ H 2 = 



BrC- 



CO 



\ 



O + HBr 

 HC - CH, 



The isomerism observed in the monohalogenized crotonolactones 

 must be due to the position of the halogen atoms, since, according to 

 the views at present held concerning geometric isomerism, lactones can 

 be formed from the maleinoid forms only. A definite proof that the 



