140 PROCEEDINGS OF THE AMERICAN ACADEMY 



IV. On Certain Tetrasubstituted Propionic Acids. 



By Henry B. Hill and Charles F. Mabert. 



In a previous communication * one of us has already mentioned the 

 fact that the dibromacrylic from mucobromic acid, unlike the dichlor- 

 acrylic acid of Wallach, takes up a molecule of bromine with readiness 

 and forms a tetrabrompropionic acid. We were led to undertake a 

 more complete study of the tetrasubstituted propionic acids, especially 

 with the hope that the study of those containing two different halo- 

 gens might throw some light upon the position of the halogen atoms 

 in the disubstituted acrylic acids formed from mucobromic and muco- 

 chloric acids. After our investigations were concluded Mauthner and 

 Suida t published in the Proceedings of the Vienna Academy a paper 

 entitled " Ueber gebromte Propionsiiuren und Acrylsliuren," in which 

 they anticipate us in the publication of a portion of our work. Since 

 they were perfectly well aware that, in studying derivatives of a sub- 

 stituted acrylic acid which they asserted, although without adequate 

 proof, was identical with that obtained from mucobromic acid, they 

 were trespassing upon ground which one of us had already fully re- 

 served, we think it advisable, although it involves a certain amount of 

 repetition, to give our results in full, more especially since we are able 

 to correct their work in several important particulars. 



Tetrahrompropionic Acid. 



Tetrabrompropionic acid can readily be made by the addition of 

 bromine to dibromacrylic acid at ordinary temperatures. J We have 

 prepared it by adding to a solution in chloroform the calculated amount 

 of bromine. On standing, the addition product gradually separates, 

 often in large, well-formed prisms. The amount of the product thus 

 obtained was about 90% of the theoretical yield. After recrystalliza- 

 tion from chloroform the substance was dried over sulphuric acid. 



* Tliese Proceedings, Vol. XVI. (n. s. viii.) p. 197. 



t Sitzungsbcrichte der kk. Akademie, Wicn, lx.\.\iii. 273. 



\ Mauthner and Suida assert that the dibromacrylic acid will take up no 

 bromine in tlie cold. They prepared tetrabrompropionic acid by heating to 

 100° witb undiluted bromine. That the bromine is very readily taken up one 

 of us first mentioned several years ago (Berichte der deutsch. chem. Gesellsch., 

 1. xii.657). 



