ANTHRAQUINONE. 407 



water, but slightly soluble in alcohol, ether, and cold 

 benzene, more easily in hot benzene. Very stable ; 

 alcoholic potassa-ley produces no effect upon it. Heated 

 with hydriodic acid at 150, or with zinc-dust, it is 

 converted into anthracene. Fused with caustic potassa 

 it yields benzoic acid. 



Dichloranthraquinone, C 14 H 6 C1 2 2 . Is obtained 

 by oxidizing tetrachloranthracene like anthraquinone. 

 Yellow needles. 



Monobromanthraquinone, C 14 H 7 Br0 2 . By oxida- 

 tion of tribromanthracene. Bright-yellow needles; 

 fusing point, 187 ; sublimable. JDibromanthraquinone^ 

 C 14 H 6 Br 2 O 2 . By heating anthraquinone with two 

 molecules bromine at 100 ; more readily by oxidizing 

 tetrabromanthracene. Bright-yellow needles ; sub- 

 limable. 



Dinitroanthraquinone, C 14 H 6 (]TO 2 ) 2 2 . Is formed 

 together with anthraquinone, by heating anthracene 

 with dilute nitric acid. From the solution of the pro- 

 duct in a great deal of hot alcohol, it separates first on 

 cooling. It is more readily obtained by the action of 

 nitric-sulphuric acid on anthraquinone. Small, bright- 

 yellow, monoclinate crystals; difficultly soluble in 

 alcohol, ether, and benzene ; sublimes in the form of 

 yellow needles, at the same time undergoing partial 

 decomposition. Combines with hydrocarbons, the 

 same as picric acid, forming very characteristic com- 

 pounds. 



piamidoanthraquinone, C 14 H 6 (KH 2 ) 2 2 . Is ob- 

 tained from dinitroanthroquinone by warming with tin 

 and hydrochloric acid, or with a solution of sodium 

 sulphydrate. Small, cinnabar-colored needles ; fusing 

 point, 236. Scarcely soluble in water, soluble in alco- 

 hol, ether, and concentrated acids. Sublimes in garnet- 

 colored, flat needles. Very weak base. From its 

 solutions in acids it is thrown down in a free condition 

 on the addition of water. 



