JACKSON AND CALVERT. METaPHENYLENE DIAMINE. 145 



The zinc dust contained in a flask kept full of carbonic dioxide was 

 covered with acetic acid of 80 per cent, and the tribromdinitrobenzol 

 added in small quantities at a time. If the zinc dust and tribromdi- 

 nitrobenzol were mixed together before adding the acetic acid the 

 action was far too violent ; in fact, once the mixture took fire when 

 the acetic acid was added. Even when the process was carried on as 

 directed, the action was energetic at first, but later it was necessary to 

 warm the flask gently to assist the reaction. The products were in 

 part dissolved in tlie aqueous lic^uid, which with all our precautions 

 was invariably dark colored, and partly appeared as a crystalline pow- 

 der in the bottom of the flask. The insoluble part was recrystallized 

 from benzol, by which it was separated into a large fraction melting 

 at 158°, a small amount of substances melting at a lower temperature, 

 and a little unaltered tribromdinitrobenzol. The principal product 

 was shown to be tribromphenylene diamine by its melting point, but 

 to confirm this it was dried at 100° and analyzed, when it gave the 

 following results : — 



0.2337 gram of the substance gave by the method of Carius 0.3786 

 gram of argentic bromide. 



Calculated for Found. 



CpHBralNHa)^. 



Bromine 69.56 68.95 



This percentage of bromine, although not agreeing with that calcu- 

 lated so closely as could be wished, is yet accurate enough when taken 

 in connection with the melting point to leave no doubt as to the nature 

 of the substance formed, and therefore we did not attempt to get a 

 number nearer to the theoretical. 



The amount of tribromphenylene diamine formed by the reduction 

 was considerable ; in one case 10 grams of tribromdinitrobenzol yielded 

 4.7 grams of it, and 0.9 gram of tribromdinitrobenzol were recovered 

 unaltered, so that the percentage of the theoretical yield was 60.6. The 

 remainder of the product was contained in the aqueous solution (and to 

 a less extent in the small amount of lower melting material from the 

 benzol mother liquors) ; it undoubtedly consisted of phenylene diamine, 

 from which part or all the bromine had been removed, since the aqueous 

 solution gave tribromphenylene diamine when treated with bromine 

 water, a behavior which, as we have already stated, belongs to solu- 

 tions of phenylene diamine and its salts. 



Reduction with Tin and Hydrochloric Acid. We found it best to 

 proceed as follows : Some granulated tin with a piece of platinum 

 and about 300 c.c. of strong hydrochloric acid were gently warmed in a 

 VOL. XXXI. (n. s. xxiii.) 10 



