JACKSON, DUNLAP, — BROMINE DERIVATIVES OP RESORCINE. 233 



tallized from alcohol till it showed the constant melting point of 12G°, 

 after which it was dried at 100° and analyzed. 



0.1313 gram of the substance gave 13.5 c. c. of moist nitrogen at a 

 temperature of 26° and a pressure of 746.6 mm. 



Calculated for 

 C 6 (N0 2 ) 2 H 2 (0C 2 H 5 ) 2 . Found. 



Nitrogen 10.94 11.19 



Properties. — The dinitroresorcine diethylether crystallizes from 

 alcohol in radiated clusters of long white needles, or of smaller curved 

 needles forming woolly masses. It is of a very faint yellow color and 

 melts when pure at 126°. It is readily soluble in chloroform and 

 acetone ; slightly soluble in ligroin ; soluble in benzol ; tolerably soluble 

 in carbonic disulphide ; soluble also in ether. Alcohol is the best sol- 

 vent for purification. 



Tribromresorcine, C 6 H Br 3 (OH) 2 . 



Tribromresorcine was prepared by the method of Benedikt,* as this 

 yields better results than the treatment of resorcine dissolved in water 

 with bromine, used by Hlasiwetz and Barth.f For this purpose the 

 calculated amount of bromine is run into a solution of resorcine in 

 cold glacial acetic acid. After the addition of the bromine this solu- 

 tion is somewhat warm, and upon cooling a finely crystallized product 

 separates, which is best washed free from acetic acid by decantation. 

 If more than the calculated amount of bromine is added, pentabrom- 

 resorcine is formed in addition to the tribromresorcine. The yield by 

 this method is slightly over 57 per cent of the theoretical. 



A great many conflicting statements occur in the chemical literature 

 regarding the melting point of tribromresorcine. Hlasiwetz and Barth, 

 who discovered it, give no melting point. Typke.J in some work on 

 tribromdioxyazobenzol, obtained a body with a constant melting point 

 of 104°. The amount of this body that he had was too small for 

 analysis, but a careful comparison of its properties, especially its 

 melting point, its crystalline form, and its solubility, with that of 

 tribromresorcine he had prepared himself, convinced him of the iden- 

 tity of the two substances. 



Rudolph Benedikt § by the action of tin and hydrochloric acid 

 upon Stenhouse's pentabromresorcine, obtained tribromresorcine which 



* Monatsh. f. Chem., IV. 227. \ Ber. d. ch. G., X. 1578. 



t Ann. Chem., CXXX. 357. § Ibid., XI. 2168. 



