148 PROCEEDINGS OF THE AMERICAN ACADEMY. 



mine can be removed from tribrommetaphenylene diamine by the action 

 of tin and hydrochloric acid, it occurred to us that the comparatively loose 

 attachment of the bromine to the benzol ring might be due to the fact 

 that the three atoms of bromine were in the symmetrical position, since 

 Blau has shown that one of these atoms in tribrombenzol can be replaced 

 by the methoxy radical, and we have confirmed this observation. This 

 hypothesis seemed the more probable because dibrommetaphenylene 

 diamine is reduced under these conditions much more slowly than the 

 tribrom compound. If this view is correct, tin and hydrochloric acid 

 should remove bromine from the symmetrical tribrombenzol, and ac- 

 cordingly we tried the following experiment. Ten grams of tribrom- 

 benzol were mixed with granulated tin and strong hydrochloric acid, a 

 piece of platinum added to promote the action, and enough alcohol to dis- 

 solve a large part of the tribrombenzol. The reason for adding the alcohol 

 was that we thought the action of the reducing agent on the tribrom- 

 metaphenylene diamine might be in part due to its tendency to dissolve 

 in the acid, or still more to the solubility of the products of the reduc- 

 tion in the acid, and we hoped by the addition of the alcohol to establish 

 similar favorable conditions in the case of the tribrombenzol. The mix- 

 ture was heated under a return condenser on the water bath for a week. 

 At the end of this time enough water was added to precipitate any brom- 

 benzols which might be present, and the heavy crystalline precipitate 

 thus obtained was filtered, and washed until it was free from stannous 

 chloride. It was then dried and weighed, when 9.5 grams were ob- 

 tamed, so that the loss was no greater than would be expected from 

 the rough way in which the experiment had been carried on. This 

 substance melted at 120°, and was therefore unaltered tribrombenzol 

 (melting-point 119.6°). It follows from this experiment that tin and 

 hydrochloric acid do not remove bromine from symmetrical tribrom- 

 benzol, and, therefore, that the conversion of tribrommetaphenylene 

 diamine into metaphenylene diamine by these reagents is not due to 

 the symmetrical position of the bromine atoms, although it may have a 

 subsidiary effect in assisting this conversion. 



An experiment similar to that just described was tried with 10 

 grams of tribromaniline. The conditions were exactly the same as 

 those used for tribrombenzol, given at length in the preceding para- 

 graph. Upon adding water to precipitate the organic substances, after 

 the reduction was completed, only a very small precipitate was formed, 

 which in time changed to long needles. This precipitate weighed less 

 than 0.5 gram, and as it melted at 118° was undoubtedly unaltered 

 tribromaniline. The filtrate from this precipitate was treated with 



