JACKSON AND KOCH. — TRIBROMDINITROBENZOL. 127 



crucible, taking care that the temperature was kept just below boiling. 

 It was then allowed to stand over night at ordinary temperatures, when 

 most of the tribromdinitrobenzol crystallized out, while the rest of it was 

 obtained by pouring the supernatant acid liquid into a large excess of 

 water. The dried product was purified by crystallization from about 

 eight times its weight of a niixture of three parts of alcohol with one 

 of benzol. 



Action of Sadie Ethylate on Tribromdinitrohenzol at 70°. 



The tribromdinitrobenzol used in all this work, made in the way de- 

 scribed in the previous section, melted at 192°, and had the constitution 

 lir3l,3,o,(N02)22,4. Forty grams of this tribromdinitrobenzol were dis- 

 solved in 80 c.c. of benzol, and mixed with the solution of sodic ethylate 

 obtained from 6.8 grams of sodium and 180 c.c. of absolute alcohol, 

 wliich gave the proportion of three molecules of sodic ethylate to each 

 molecule of tribromdinitrobenzol. The flask containing the mixture was 

 then placed in a water bath, which was heated until a thermometer im- 

 mersed in the mixture rose to 70°, at which temperature the solution was 

 kept for ten minutes. The liquid turned dark brown during this heating, 

 a color which had been found to be characteristic of the reaction with 

 the aid of heat. At the end of the ten minutes the liquid was poured 

 into a large evaporating dish, and the solvents allowed to evaporate spon- 

 taneously. The residue thus obtained was washed with water until tha 

 wash waters became colorless, and the products purified as follows. 



Residue Insoluble in Water. 



This residue was dried and extracted three times with boiling ligroin. 

 The portion insoluble in ligroin was purified by repeated crystallization 

 from a mixture of ligroin and benzol, during which it was frequently 

 treated with boneblack. The product was the diuitroresorcine diethyl- 

 ether already obtained in this way by W. H. Warren and one of us;* 

 it was recognized by its melting point, 133°, and its solubilities and 

 appearance. 



The ligroin solution on standing deposited a flocculent precipitate in 

 too small quantity for identification, which was filtered out, and the fil- 

 trate evaporated to dryness ; the crystalline residue was spread on an 

 ungluzed plate to remove oily impurities, after which it was purified by 

 crystallization from hot ligroin. After four crystallizations it showed 



* These Proceedincrs, XXV. 170. 



