JACKSON AND KOCH. — TRIBROMDINITROBENZOL. 123 



same position toward the three atoms of bromine as the three nitro groups 

 do in our body) was removed only after long boiling of the benzol and 

 alcohol solution, and then incompletely. 



D. The loosening effect of the three bromine atoms on each other. 

 This is a feeble effect, as Blau * found it necessary to heat symmetrical 

 tribrombenzol to 120°-130° with sodic ethylate to obtain much effect. 

 Calvert and one of us f found that with sodic ethylate a reaction took 

 place at the boiling point of alcohol in open vessels, but the reaction ran 

 more slowly, and was less complete than that witli tetrabrombenzol. 



We have then the most powerful loosening effect A, and the weakest 

 loosening effect D, exerted on the atoms of bromine, while the two inter- 

 mediate effects B and G influence the nitro groups, so that A -{■ D '\?, 

 very nearly, if not quite, equal io B -\- (J; that is, the attack of the sodic 

 ethylate will be directed about equally upon the atoms of bromine and 

 upon the nitro groups, which was the result of our experimental work as 

 stated above. 



A similar discussion of the action of sodic ethylate on tribromdinitro- 

 benzol gives the following results. The loosening effects are marked by 

 letters, and arranged in order of intensity, as before. 



E. The action of the two nitro groups in loosening the three atoms 

 of bromine. This is a strong effect, as shown by the ease with which the 

 bromdinitrobenzol Brl(NOo)22,4, is decomposed by potassic hydrate. $ 



F. The effect of the three atoms of bromine on the two nitro groups 

 already discussed. 



G. The effect of the three atoms of bromine on one another, which has 

 also been considered in the previous discussion. 



H. The effect of the two nitro groups on each other. So far as we 

 can find, this effect is too feeble to produce a replacement of a nitro group 

 by an ethoxy group, but it should not be left out of account, as Lobry de 

 Bruyn § has found that potassic cyanide in alcoholic solution converts 

 metadinitrobenzol into CgHsNOjOCaHsCN, which shows a certain loos- 

 ening of one of the nitro groups. 



Here then we have only one strong loosening agency (^E), and this 

 acts on the atoms of bromine, while of the other three by far the feeblest 

 (^H) is one of those acting on the nitro groups. It is evident there- 

 fore that 



E+ G> F+ H, 



* Monatsh. f. Chem., VII. 630. J Clemm, Journ. Pr. Chem., [2], I. 145. 



t These Proceedings, XXXI. 134. § Rec. Trav. Chim. Pays Bas, II. 205. 



