.236 PROCEEDINGS OF THE AMERICAN ACADEMY 



Preparation of Bromdinitrophenylmalonic Ester. 



Our longer experience in the preparation of bromdinitrophenyl- 

 malonic ester has led us to introduce several improvements into the 

 process, which now we carry on as follows. A strong benzol solu- 

 tion of 20 grs. of tribromdinitrobenzol (benzol is to be preferred to 

 the ether used formerly, because the tribromdinitrobenzol is more 

 soluble in it) is mixed with 16 grs. of malonic ester jjreviously con- 

 verted into sodium malonic ester by treatment with the sodic ethylate 

 from 2.3 grs. of sodium and about 100 to 125 c.c. of alcohol, and the 

 mixture allowed to stand over night at ordinary temperatures. The 

 red solution thus obtained is treated with water, which separates it 

 into two layers, a dark red aqueous solution containing the sodium 

 salt of bromdinitroiihenylmalonic ester and sodic bromide, and a ben- 

 zol solution of the unaltered tribromdinitrobenzol with the oily product 

 of the reaction. The two layers are separated with a drop-funnel, 

 and the lower aqueous one acidified with dilute sulphuric acid ; this 

 throws down a yellowish white precipitate of the bromdinitrophenyl- 

 malonic ester, which is purified by crystallization from hot alcohol, 

 until it shows the constant melting point 76°. 



In this way 20 grs. of tribromdinitrobenzol gave 7.9 grs. of the 

 bromdinitrophenylmalonic ester,* and 5.1 grs. of tribromdinitrobenzol 

 were recovered from the benzol solution. Subtracting this from the 

 20 grs. there are left 14.9 grs. of tribromdinitrobenzol, which entered 

 into the reaction, and should have given the same weight, 14.9 grs., of 

 the product, so that the yield was 53 per cent of the theory, or about 

 the same as that obtained by the process as given in om* first jjaper, 

 which calculated in the same way becomes 50 per cent. 



In the course of some other experiments the curious observation 

 was made that it is not necessary to use sodic ethylate to bring 

 about the action of malonic ester on the tribromdinitrobenzol, as a 

 little of the red salt of bromdiuitrophenylmalonic ester was formed 

 when aqueous sodic hydrate was added to a mixture of the two organic 



* Dr. G. D. Moore, in his work with me on tlie action of sodium acetacetic 

 ester on tribromdinitrobenzol, has found that a much better yield is obtained if 

 the mixture is boiled for an hour under a return condenser, Tliis observation 

 was not made until the work described in this paper was finished and Mr. 

 Robinson had left Cambridge, so that it was not convenient to try the experi- 

 ment of boiling the solution of sodium malonic ester and tribromdinitrobenzol, 

 nor did it seem very desirable to do so, as when we first took up the subject 

 such an experiment was tried, and seemed to yield very unfavorable results. 

 I propose, however, to repeat the experiment next year, if I return to the study 

 of these compounds. C. L. J. 



