222 PROCEEDINGS OF THE AMERICAN ACADEMY 



CHgBr 



CBr^ 



COOH 



Although this is the constitution assigned to it by Michael and Nor- 

 ton,* it is evident that this formula is based upon a pure assumption 

 concerning the structure of the a monobromacrylic acid from which it is 

 made. 



No more decisive arguments against the second formula can be 

 drawn from the reactions or the derivatives of the dibromacrylic acid, 

 although the formation of malonic acid follows more simply from the 

 first formula, and the forms, — 



which the second formula renders necessary for bromacetylen and 

 brompropiolic acids, seem hardly in its favor. It would therefore 

 seem probable that the structure of mucobromic acid is, — 



CBr^ — CHO 



= C — COOH 



The close connection between the disubstituted acrylic acids derived 

 from mucobromic and mucochloric acids and maleic acid makes their 

 further study extremely desirable, more especially in order to obtain 

 additional evidence bearing upon the position of the halogen atoms. 

 Investigations in this direction are now in progress in this laboratory. 



* Amer. Chem. Journ., ii. 18. 



