166 PROCEEDINGS OF THE AMERICAN ACADEMY 



dinitrodibrom compound,* and to a less extent in the trinitro deriva- 

 tive t ; while the I'eplacement of bromine by hydrogen, mentioned 

 under the third head, corresponds closely to the removal of the 

 second atom of bromine from all these substances. In regard to the 

 replacement of the nitro groups instead of the atoms of bromine by 

 ethoxy or methoxy radicals, described under the fourth head, we can 

 only say that the conditions were essentially the same as those under 

 which the bromine in the dinitro compound was replaced, and that 

 as yet we have no hint of an explanation for it, but hope that future 

 experiments will throw some light on the cause of this strange be- 

 havior. We may here call attention to the fact, that the replacement 

 of these nitro groups is in direct contradiction to Laubenheimer's 

 rule.t that a nitro group is removed only when it is in the ortho 

 position to another nitro group, since in the tribromtrinitrobenzol 

 the three nitro groups are in the meta position to each other. 

 Whether this exception to Laubenheimer's rule is due to the fact 

 that it does not apply to sodic ethylate, or to some cause peculiar to 

 the tribromtrinitrobenzol, must be determined by future experiment. 



We also found that neither sodic acetate nor sodic picrate acted on 

 tribromdiuitrobenzol even at 100°, nor did sodic picrate act on tri- 

 bromtrinitrobenzol, which justifies the inference that decidedly acid 

 radicals cannot be taken up by these molecules, which contain so 

 many nitro groups. Also we have repeated the experiment on the 

 action of malonic ester upon tribromdiuitrobenzol and confirm the 

 negative results previously obtained. § 



The description of the experimental details of the research occupies 

 the rest of the paper. 



Action of Sodic Ethylate on Trihromdinitrohenzol in the Cold. 



In order to study this action 20 gr. of tribromdiuitrobenzol (melt- 

 ing point 192°, made from symmetrical tribrombenzol) dissolved in 

 a mixture of 40 c.c. of benzol and 90 c.c. of absolute alcohol were 

 treated with an alcoholic solution of the sodic ethylate, made from 

 3.4 gr. of sodium, which gave the proportion of three molecules of 

 sodic ethylate to one of tribromdiuitrobenzol. That a reaction took 

 place was indicated by the appearance of a pale reddish yellow color, 

 which gradually increased in intensity to a dark brownish red, but 

 there was no perceptible evolution of heat. To give the reaction 



* These Proceedings, xxiv. 294. J Ber. d. ch. G., ix. 766, 1828. 



t Ibid., 258. § These Proceedings, xxiv. 308 (1889). 



