244 PROCEEDINGS OF THE AMERICAN ACADEMY 



Comparison of the Three Monobrombenzylhromides. 



One gramme of each substance was weighed in a wide-mouthed 

 flask, the cork of which was fitted with a return-condenser and a short 

 wide tube closed with a cork for the addition of the reagents, 10 c.c 

 of absolute alcohol were added, and the mixture heated for seven 

 minutes in a boiling water-bath. After which, 25 c.c. of a saturated 

 solution of sodic acetate in 99 per cent alcohol, at 60° to 70°, were 

 introduced, and the flask heated for a definite time, varied in each 

 series of exjjeriinents; care being taken that the water-bath boiled 

 violently during the whole time, and that the three flasks to be com- 

 pared were immersed to the same depth, and arranged symmetrically 

 in the bath. The action was stopped by the addition of a large quan- 

 tity of water, the flask being removed from the bath at the same time ; 

 and, after filtering out the organic matter, the quantity of sodic 

 bromide formed by the reaction was determined by Volhard's * excel- 

 lent method of titration with sulphocyanate. 



The brombenzylbromides used were made in the way described in 

 the first paper f of this series, and purified with the utmost care. 



The sodic acetate was prepared by drying the crystallized salt in an 

 air-bath. It yielded on analysis the following result : — 



0.7720 grm. of NaCgHgO^ gave 0.6655 grm. of Na^SO^. 



Calculated. Found. 



Sodium 28.05 27.93 



The absolute alcohol did not turn anhydrous cupric sulphate blue, 

 and neither it nor the acidified solution of the sodic acetate gave a 

 precipitate with argentic nitrate. 



The 25 c.c. of the alcoholic solution of sodic acetate contained a 

 little more than enough of the salt to decompose the one gramme of 

 brombenzylbromide used, since, — 



10 c.c. of this solution yielded on evaporation 0.136 grm. of sodic 

 acetate, and therefore, — 



25 c.c. contained 0.340 grm. 



Needed for 1 grm. brombenzylbromide . . 0.328 grm. 



Excess 0.012 erm. 



* Ann. Chem. u. Pharm., cxc. p. 1. 



t Tliese Proceedings, vol. xii. (n. a. iv.) p. 211. 



