OF ARTS AND SCIENCES. 279 



XI. 



CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 



HARVARD COLLEGE. 



By Charles F. Marery. 



Presented March 12, ISSl. 



No. L — ON ^-BROMTETRACHLORPROPIONIC ACID. 



"With the hope of establishing the structure of certain bromdichlor- 

 acrylic acids which I have at present under examination, I endeavored 

 to prepare an acid of the same empirical composition by the addition 

 of a molecule of chlorine to bromproj^iolic acid.* 



In studying the relations of these substances toward each other 

 under different conditions, it was found that the action of chlorine 

 upon the melted acid was so violent that frequently it resulted in an 

 explosion. Even at ordinary temperatures a gaseous product was 

 freely evolved, with a disagreeable odor resembling that of phosgene. 



As previous experiments had shown, in a chloroform solution of the 

 acid the action of chlorine could easily be controlled ; in fact, for some 

 time it could not be determined whether the addition had beofun, since 

 evaporation of the chloroform left only a pasty mass which refused to 

 crystallize. Finally, after continuing the action for several hours, a 

 crust began to form above the solution, and soon the greater part of a 

 crystalline addition product was deposited. 



This substance proved to be sparingly soluble in cold carbonic di- 

 sulphide and chloroform, more soluble in hot, and after purification it 

 melted with decomposition at 225°. The percentage composition cal- 

 culated from the results of analysis corresponds to that of bromtetra- 

 chlorpropionic acid. 



* In a former paper (Maberj and Robinson, these Proceedings, Vol. XVIII. 

 p. 45) it was stated that a bromdichloracrylic acid could be prepared by passing 

 chlorine through a chloroform solution of brompropiolic acid cooled to 0°. This 

 statement was evidently made upon insufficient evidence, since all subsequent 

 attempts to obtain tlie same result have proved unsuccessful. 



