27G PROCEEDINGS OP THE AMERICAN ACADEMY 



II. 12 grs. of tribromdinitrobenzol yielded 4.40 grs. of bromine in 

 tbe form of sodic bromide. 

 If two atoms of bromine are removed from each molecule by this re- 

 action, 12 grs. of tribromdinitrobenzol would lose 4.74 grs. of bromine. 

 Percentage of bromine removed as sodic bromide, — 

 i. ii. 



93.5 93.0 



From this it appears that all the bromine removed from the tribrom- 

 dinitrobenzol is finally in the state of sodic bromide, as the sligbt loss 

 of 7 to 6.5 per cent is not greater than wonld be expected when it is 

 considered that the aqueous solution containing the sodic bromide was 

 shaken out twice with ether. These determinations show also that in 

 these cases the whole of the tribromdinitrobenzol entered into the re- 

 action, and in fact none of it could be found unaltered in the products 

 of these two preparations ; but this was not always the case, as, for in- 

 stance, in the preparation described on page 275. 



The full explanation of the reaction, however, was to be found in 

 the study of its secondary product, the red oil removed from the crys- 

 tals by washing with cold alcohol. This, upon long standing exposed 

 to the air, threw down a few more crystals of bromdinitrophenyl- 

 acetacetic ester, which would raise the yield a little above that given, 

 but the amount obtained in this way was very small. The oil, after 

 no more crystals could be obtained from it, was distilled under di- 

 minished pressure and yielded some acetacetic ester, leaving in the flask 

 a tarry mass which has shown no signs of giving crystals even after 

 long standing. This part of the work therefore was not carried fur- 

 ther, as from the formula of the ester and the removal of all the bro- 

 mine as sodic bromide there can be no doubt that the reaction with 

 acetacetic ester runs in the same way as that with malonic ester, and in 

 this latter case the reaction has been fully explained.* Reasoning on 

 this analogy, the following reactions may be taken as expressing what 

 takes place in the formation of the bromdinitrophenylacetacetic ester. 



C 6 HBr 3 (N0 2 ) 2 + 2 CH 3 COCHNaCOOC 2 H. = 

 ' C 6 HBr 2 (Na),CH„COCHCOOC 2 H 5 + NaBr 



+ CH,COCHNaCOOC 2 H 5 = 

 C s IIBr„(N0 2 ) 2 CII 3 COCNaCOOC 2 H 5 + CH 3 COCII 2 COOC 2 H 5 



+ NaBr = 

 C 6 n 2 Br(N0 2 ) 2 CII ! COCNaCOOC 2 II 5 + CH,COCIIBrCOOC 2 H 5 



+ NaBr. 



* These Proceedings, xxiv. 238, 265. 



