406 PROCEEDINGS OF THE AMERICAN ACADE3IY. 



of glacial acetic acid, and adding liquid bromine until it was present 

 in distinct excess, as shown by the reddish brown color of the liquid. 

 To make certain that the reaction was complete, the liquid was 

 warmed gently on the steam bath for a few minutes, and then allowed 

 to stand at ordinary temperatures for an hour, after which water was 

 added in excess, giving a pale yellow precipitate partly solid and partly 

 liquid. After this had settled, the supernatant liquid, colored red 

 with the excess of bromine, was poured off, and the liquid part solidi- 

 fied by cooling. It was then washed with water, dried by pressure on 

 filter paper, and purified by recrystallization from alcohol until it 

 showed the constant melting point 85°-86°, when it was dried in 

 a desiccator, and analyzed with the following result : — 



0,1873 gram of the substance gave by the method of Carius 0.0789 

 gram of argentic bromide. 



Calculated for 

 C6H2(N0,)3CBr(C00C2Hg)2. Found. 



Bromine 17.78 17.93 



It is obvious that this atom of bromine, the presence of which is 

 shown by the analysis, may have entered the molecule in one of two 

 different places, either replacing the hydrogen of the malonic ester 

 radical, as in the formula given above, or replacing one of the atoms 

 of hydrogen attached to the benzol ring. It is easy to determine 

 which position the bromine occupies, for, if it is attached to the 

 malonic ester radical, the substance will have lost all its acid proper- 

 ties, since the acid hydrogen has been replaced by 4he atom of bro- 

 mine. In the second case, where the bromine is attached to the benzol 

 ring, on the other hand, the acid properties will not be interfered with, 

 but on the contrary will be somewhat increased if the bromine atom 

 has any effect whatever. Upon treating our new substance with a 

 solution of sodic carbonate no change was observed, whereas the picryl- 

 malonic ester is converted at once into its red salt by this reagent; 

 as, therefore, this substance has no acid properties, it follows that the 

 bromine has entered the malonic ester radical, and the formula given 

 above is the correct one. 



Properties of Picrylbrommalonic Ester. — It crystallizes from alcohol 

 in white plates, nearly but not quite square, and much striated ; these 

 plates are arranged in irregular rather long rosettes. Less commonly 

 it occurs in bladed or pennate forms. In general appearance it resem- 

 bles acetanilid. It melts at 85°-86°, and is very soluble in chloro- 

 form or benzol ; rather less soluble in ether, carbonic disulphide, or 

 glacial acetic acid ; soluble in cold alcohol, freely soluble in hot ; rather 



