JACKSON AND KOCH. — TRIBROMDINITROBENZOL. 131 



by crystallization from a mixture of alcohol and benzol showed the con- 

 stant melting point 105^, which suggested that they were the dinitrophlo- 

 roglucine triethylether discovered by W. R. Lamar and one of us.* To 

 settle the nature of the substance, it was dried at 100° and analyzed with 

 the following result : — 



0.2297 gram of the substance gave 19.4 c.c. of nitrogen at a tempera- 

 ture of 23° and a pressure of 750 mm. 



Calculated for 

 CoU(,OC2H5>s{NOj),. Found. 



Nitrogen 9.34 9.42 



It is therefore the dinitrophloroglucine triethylether. 



Tlie ligroin mother liquor, from which the dinitrophloroglucine tri- 

 ethylether had been deposited, was evaporated to dryness, and spread on 

 a porous plate to remove oily impurities, after which it was diss^olved in 

 hot ligroin, and allowed to crystallize, when in addition to the square 

 prisms of dinitrophloroglucine triethylether long needles with square 

 ends were observed, which resembled the bromdinitroresorcine diethyl- 

 ether melting at 92°, obtained by the action of a hot sodic ethylate solu- 

 tion on tribromdinitrobenzol, as described earlier in this paper. The iso- 

 lation of this substance from the mixture of crystals proved a matter of 

 great difficulty. Hot ligroin did not accomplish this, and a number of 

 other solvents were tried with no better success. Finally, on soaking the 

 mixture for some time with cold ligroin, it was found that a considerable 

 amount of ths square prisms remained undissolved; these were filtered 

 out, and the filtrate on evaporation gave a residue, which was once more 

 extracted with cold ligroin in the same way. This second extract 

 yielded crystals, which could be purified by crystallization from hot 

 ligroin, when their constant melting point 92° and their solubilities and 

 crystalline form proved that they were the bromdinitroresorcine diethyl- 

 ether (OaH5),l,3,Br5,(NO,),2,4. 



Although the dinitrophloroglucine triethylether was formed freely in 

 the cold, we obtained none of it when we carried on the reaction at 70°. 

 This was probably due to the short duration of our* experiments (ten 

 minutes), as there is little doubt that this substance is produced by the 

 further action of the sodic ethylate on the bromdinitroresorcine diethyl- 

 ether at first formed. It follows that the best way of making the die- 

 thylether melting at 92° is the process described under the action of sodic 

 ethylate at 70°. 



* Am. Chem. Journ., XVIII. 670. 



