OP ARTS AND SCIENCES. 241 



XII. 



CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF HAR- 

 VARD COLLEGE. 



RESEARCHES ON THE SUBSTITUTED BENZYL COM- 

 POUNDS. 



By C. Loring Jackson. 



TENTH PAPER. 



THE RELATIVE CHEMICAL ACTIVITY OF CERTAIN SUBSTI- 

 TUTED BENZYLBROMIDES. 



Presented November 12, 1879 



In the following paper I have the honor of laying before the Acad 

 emy an account of sonae experiments undertaken to compare the ease 

 with which bromine can be removed from the side-chains of the sub- 

 stituted benzylbromides described in the first paper of this series ; 

 in other words, an attempt to establish some relation between the 

 structure of a molecule and its chemical activity. The differences in 

 structure, which I have taken up, are of two sorts, — those depending 

 on difference in the position of the same element, as in the three 

 monobrombenzylbromides ; and those depending on the presence of 

 different but related elements in the same position, as in parachlor-, 

 parabrom-, and paraiodbenzylbromide. 



After a careful consideration of the reagents by which the side- 

 chain bromine could be removed from these substances in a simple 

 metathetical reaction, I decided that sodic acetate promised the best 

 results, and, after many experiments, adopted a method, which con- 

 sisted in treating equivalent amounts of the substituted benzylbromides, 

 for the same length of time and under the same conditions, with an 

 alcoholic solution of sodic acetate, and determining by volumetric 

 analysis the amount of sodic bromide formed from each according to 

 the following general reaction, — 



VOL. XVI. (N. S. VIII.) 16 



