212 PROCEEDINGS OF THE AMERICAN ACADEMY 



either from the factory of Kahlbaum, in Berlin, or of Schuchardt, in Gor- 

 litz, were heated to boiling in a small flask, through whose cork passed a 

 return-cooler and the delivery-tube from a flask containing 10 gr. of 

 bromine, the end of which within the flask was less than a centimeter 

 above the sui'face of the bromtoluol ; the bromine was driven over in 

 the form of vapor by heating the flask containing it with a small flame 

 placed some distance below at such a rate that it was completely de- 

 colorized at a few centimeters from the end of the exit-tube : to pre- 

 vent condensation of the bromine, the delivery-tube was made as short 

 as possible ; the heat was carefully regulated so that the bromtoluol 

 boiled gently, the explosive boiling with evolution of white fumes, 

 which was apt to occur toward the end of the process, being especially 

 avoided. If these precautions were observed, the liquid solidified 

 almost completely on cooling, and the substance was easily purified by 

 j)ressing the crystals thus obtained between filter-paper and recrystal- 

 lizing once or twice from hot alcohol. The average yield from ten 

 grammes of parabromtoluol was ten grammes of parabrombenzylbro- 

 mide, that is about sixty-eight per cent of the theoretical amount; but, 

 if more than ten grammes of parabromtoluol were used in one opera- 

 tion, the yield was not so large. 



The substance was also obtained from the mixture of para- and ortho- 

 bromtoluol,* prepared by treating cold toluol with bromine. On cooling 

 the product of the action of bromine on the hot mixture with ice and 

 salt, some parabrombenzylbromide separated out, and more was ob- 

 tained by distilling off a part of the oil with steam, as the orthobrom- 

 benzylbromide distils more easily with steam than the paracompound. 

 This distillation is not to be recommended, however, as under these con. 

 ditions a portion of the bromide is converted into the corresponding 

 alcohol ; but without doubt this difficulty could be I'emoved by using 

 hydrobromic acid in jilace of water. Compare p. 214. 



Second Method. Benzylbromide was treated in the cold with an 

 equal weight of bromine, to which a little iodine had been added ; on 

 freezing the product of the reaction, a quantity of parabrombenzylbro- 

 mide separated out. This method is decidedly inferior to that with 

 pure parabromtoluol, as it not only gives a smaller yield, but also there 

 is a i^ossibility that orthobrombenzylbromide may be formed. The 

 composition of the parabrombenzylbromide was established by the fol- 

 lowing analyses : — 



0.5934 gr. of substance gave 0.7377 gr. CO2 and 0.1378 gr. H^O. 



* Ann. Chem. Pliarm., 147, p. 39. 



