6 PEOCEEDINGS OF THE AMERICAN ACADEMY 



increased in order to bring more of the tribromdinitrobenzol into the 

 reaction, any gain from this cause is more than compensated by the 

 larger amount of the product taken up by the greater quantity of oil, 

 which is only in part deposited on long standing. Nor was the yield 

 increased by longer standing, or by boiling the materials with a re- 

 verse condenser ; in this latter case the product came down in an oily 

 form, and with, if anything, rather a smaller yield was much harder 

 to purify. 



Properties of the Bromdinitrophenylmalonic Ester, 

 C G H 2 Br(NO,) 2 CH( COOC 2 H 5 ) 2 . 



The substance crystallizes in pale yellow flattened needles, or long 

 plates terminated by a single plane, which forms with the sides angles 

 not very far from 90°, but distinctly obtuse and acute. It melts be- 

 tween 75° and 76°, and shows a tendency to explode at high tem- 

 peratures, so that the heat must be applied carefully when making a 

 combustion of the substance. It is not very soluble in cold alcohol, 

 but freely in hot, more soluble in methyl than in ethyl alcohol, freely 

 soluble in ether, benzol, or glacial acetic acid, even more so in chlo- 

 roform, moderately soluble in acetone or carbonic disulphide, nearly 

 insoluble in ligroine or water. Strong sulphuric' acid in the cold has 

 little action on it, although perhaps a small quantity dissolves ; on 

 warming the mixture, complete solution takes place, and addition of 

 water precipitates a solid, which seems to consist principally of un- 

 altered bromdinitrophenylmalonic ester mixed with a small amount 

 of a substance with a higher melting point, probably the compound 

 formed by the action of concentrated hydrochloric acid in sealed tubes 

 (see page 11). Nitric acid, either strong or fuming, dissolves the 

 bromdinitrophenylmalonic ester in the cold, but does not produce any 

 change of color. In this respect, it differs markedly from the corre- 

 sponding trinitro compound. If the acid solution is warmed, decom- 

 position seems to take place. 



The bromdinitrophenylmalonic ester possesses well-marked acid 

 properties, as was to be expected, since it contains a hydrogen atom 

 standing between the two carboxyls of the malonic ester and a phenyl, 

 which, as Victor Meyer* has shown, frequently exercises a negative 

 influence, much heightened in this case by the presence of the two 

 nitro groups. Sodic hydrate in either aqueous or alcoholic solution at 

 once converts it into a soluble red sodium salt, and the same salt is 



* Bcr. d. ch. G. 1887, p. 534, 1888, p. 1291 et seq. 



