258 PROCEEDINGS OP THE AMERICAN ACADEMY 



was converted into colorless crystals melting at 125°, and as they 

 melted becoming blood-red and increasing very much in volume. 

 The study of this curious substance is still unfinished : we have only 

 established the fact that it is an ester. If the action of the nitric acid 

 is long continued, another body is formed melting at 156° to a color- 

 less liquid, and dissolving in aqueous sodic hydrate with a red color. 



Sulphuric acid of specific gravity 1.44 converts the ester into the 

 metabromtrinitrotoluol melting at 143°-144°, recently discovered in 

 this laboratory by Bentley and Warren. 



The trinitrophenylendimalonic ester (melting point 123°), 



C 6 H(N0 2 ) 3 [CH(COOC 2 H 5 ) 2 ] 2 , 



was also obtained by the further action of sodium malonic ester on 

 bromtrinitrophenylmalonic ester ; strangely enough, it has less marked 

 acid properties than the bromine compound, from which it is derived. 



Preparation of Bromtrinitrophenylmalonic Ester. 



The tribromtrinitrobenzol used for this purpose was prepared 

 according to the method already given by one of us and J. F. Wing;* 

 we have found, however, that if the proportion of fuming sulphuric 

 acid is increased, a better yield is obtained. The proportions finally 

 used were, 20 grs. of tribromdinitrobenzol, 500 c.c. of the nitric acid 

 of 1.52 specific gravity, and 200 c.c. of fuming sulphuric acid, instead 

 of one third the volume of the nitric acid as previously recommended. 

 The yield obtained from the new proportions was in the neighborhood 

 of 40 per cent of the theory, running in one case as high as 45 per 

 cent, whereas the proportions recommended by one of us and Wing 

 gave on the average from 15 to 20 per cent, and only in a single 

 instance ran as high as 40 per cent. 



To convert the tribromtrinitrobenzol into bromtrinitrophenylmalonic 

 ester, one molecule of it must be treated with about three molecules 

 of sodium malonic ester. In practice we found it convenient to pro- 

 ceed as follows. 10 grs. of tribromtrinitrobenzol were dissolved in 

 about 200 c.c. of benzol with the aid of heat, mixed, while the solu- 

 tion was still moderately warm, with 10.6 grs. of malonic ester pre- 

 viously converted into the sodium compound by treatment with the 

 sodic ethylate from 1.7 grs. of sodium (a slight excess over the calcu- 

 lated amount) and about 15 c.c. of absolute alcohol, and the mixture 



* These Proceedings, xxiii. 139. 



