, CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 



HARVARD COLLEGE. 



CERTAIN DERIVATIVES OF METADIBROMDINITRO- 



BENZOL. 



By C. Loring Jackson and W P. Cohoe. 



Presented December 13, 1899. Received June 4, 1900. 



The dibromdinitrobenzol melting at 117°. 4 was made by Korner in 

 his classical research on Isomerism of the Aromatic Compounds with Six 

 Atoms of Carbon,* but' its constitution has not been determined with 

 certainty. Nietzki and Schedler f in a recent paper have proved that the 

 dichlordinitrobenzol melting at 103° has the structure Cl 2 1.3.(N0 2 ) 2 4. 6, 

 and as this substance is made from the action of fuming nitric acid on 

 metadichlorbenzol, just as the dibrom compound is made from metadi- 

 brombenzol, there is good reason to believe that they have the same 

 constitution ; but we thought it necessary to prove that this was the case 

 before we studied this dibromdinitrobenzol further. For this purpose we 

 heated the substance with aniline, and obtained the dianilidodinitrobenzol 

 melting at 186°, which Nietzki and Schedler had obtained from their 

 dichlordinitrobenzol ; the dibrom substance therefore has the structure 

 Br 2 1. 3. (N0 2 ) 2 4. 6. If aniline acted on the dibromdinitrobenzol in the 

 cold, a bromauilidodinitrobenzol, C G H 2 BrC 6 H 5 NH(NOo)o, melting at 

 157° was obtained, and this occurs in a yellow and in a red modification 

 which seem to differ in crystalline form as well as in color. This seems 

 to be a case of dimorphism, as the two forms pass into each other with 

 great ease. The yellow form is converted into the red by crystallization 

 from benzol, the red into the yellow by heating to 135°. Similar phe- 

 nomena have been observed in the cases of anilidotrinitrophenyltartronic 

 ester t and triauilidodinitrobenzol. § 



* Gazz. Chim. 1874, 305. 



t Ber. (1. chem. Ges., XXX. 1666 (1897). 



t Jackson and Bentley, These Proceedings, XXVI. 83. 



§ Jackson and Herman, Ibid. XXVII. 253. 



