JACKSON AND KOCH. — TRTBROMDINITROBENZOL. 



125 



Dinitroresorcine diethylether, melting point 133° . 

 Bromdinitroresorcine diethylether, melting point 92^ 



16 per cent. 

 9 per cent. 



Total 25 per cent. 



So that in this case 75 per cent of the substance was unaccounted for. 

 Most of this undoubtedly went into the tarry products. 



The most striking phenomenon in the action of sodic ethylate on 

 tribromdinitrobeuzol at high temperatures is the replacement by hydro- 

 gen of the atom of bromine in the otho position to both nitro groups. 

 The fact that this reaction only takes place to a very limited extent in the 

 cold may perhaps be accounted for by the sparing solubility of the brom- 

 dinitroresorcine diethylether melting at 184° in the cold alcohol and 

 benzol, so that most of it is precipitated, and therefore removed from the 

 action of the ethylate. On the other hand, as this ether is easily soluble 

 in these liquids, when hot, it would be brought into the sphere of the 

 reaction under these conditions, and the dinitroresorcine diethylether 

 would be formed. The bromdinitroresorcine diethylether melting at 92° 

 is soluble in the cold solvents, and this probably accounts for the fact 

 that a considerable amount of it was converted into the dinitrophloroglu- 

 cine triethylether even in the cold. 



It is perhaps worth while to call attention to the fact that in the re- 

 actions described in this paper the action is confined either to the atoms of 

 bromine or to the nitro groups; that is, if it has started in one set of 

 radicals in the meta position to each other, it does not extend to the other 

 set of radicals in the meta position to each other and ortho or para to 

 the first set. This observation has been made frequently in the course of 

 the investigation of which this is a part, and the principle has sometimes 

 given valuable aid in interpreting experimental results. In only a single 

 case has such an extension of the reaction beyond the limits of the first 

 set of trimeta positions been observed ; this was in the action of hot sodic 

 ethylate on tribromtrinitrobenzol,* which gave first tribromnitroresorcine 

 diethylether, and by further action bromnitroresorcine diethylether 

 Br Br Br t 



* These Proceedings, XXVII. 315. 



t The position of the atom of bromine in this substance has not been estab- 

 lisiied experimentally. 



