82 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Reduction of Symmetrical Dibromdinitrobenzol with Zinc 



Dust and Acetic Acid. 



Twenty grams of zinc dust were placed in a flask fitted with a Bunsen 

 valve and connected with a carbonic dioxide generator, acetic acid of 

 eighty-five per cent was added, and then five grams of the dibromdinitro- 

 benzol in small portions at a time, as under these conditions the reaction 

 ran quietly and smoothly, although accompanied by blackening in every 

 case. The reduction was carried on at first in the cold, but toward the 

 end of the operation the mixture was heated gently on the steam bath. 

 After two hours the reaction was complete, when the insoluble portion 

 was filtered out, and extracted with dilute alcohol, which upon cooling 

 deposited crystals melting even in the crude state at 131°. The filtrate 

 from the insoluble reduction products was treated with an excess of sodic 

 hydrate sutficieut to dissolve the zinc salts, the precipitate formed in this 

 way filtered out, and extracted with hot dilute alcohol, which gave an- 

 other portion of the crude product melting at 131°. After purification 

 by crystallization from alcohol the melting point became constant at 

 134° ; it was dried in vacuo, and analyzed with the following result: — 



0.1407 gram of the substance gave by the method of Carius 0.1976 gram 



of argentic bromide. 



Calculated for 

 C6HoBr2(NH2),. 



Found. 



Bromine 60.15 59.78 



This dibromphenylene diamine melts essentially at the same point 

 ( 1 35°) as that prepared by S. Calvert and one of us * from metapheny- 

 lene diacetamide and bromine. It also crystallizes like this in white 

 needles, which turn brown on exposure to the air. As the constitution 

 of our dibrorabinitrobenzol is Bro 1.3. (NOo).. 4. 6, it follows that this 

 dibrommetaphenylene diamine must have the corresponding constitution 

 Brol.S. (NH2)o'4. 6. 



* These Proceedings, XXXI. 150. 



