DIOXYBENZENES. 303 



2. Toluquinone, C 7 H 6 2 , is not known. Substitution- 

 products of it trichlortoluquinone and tetrachlortoluqui- 

 none ar e produced by the action of hydrochloric acid 

 and potassium chlorate on creosol (p. 309) and the 

 cresol (p. 299) contained in coal-tar. 



3. Phlorone, C 8 H 8 2 . Is obtained from the phenols 

 C 8 H 10 0, contained in coal-tar and beech-wood tar, by 

 distilling them with manganese peroxide and sulphu 

 ric acid. Yellow, needly crystals. Easily sublimable. 

 Slightly soluble in cold water, more readily in hot 

 water, easily soluble in alcohol and ether. Its vapor 

 attacks the eyes and mucous membranes violently. 



4. Thymoquinone, C 10 H 12 2 . Is obtained by distilling 

 a solution of thymol, diluted with water, with manga 

 nese peroxide. Yellow, prismatic plates ; fusing point, 

 45.5 ; boiling point, 200 ; volatile with water vapor. 

 Has a peculiar penetrating odor. Yields, with bro 

 mine, mono- and dibromthymoquinone. The former crys 

 tallizes in long, yellow needles, which, when heated 

 with potassa-ley, are converted into oxythymoquinone, 

 C 10 II n (OH)0 2 ; the latter forms bright-yellow laminse 

 that fuse at 73.5. 



c. Diatomic Phenols. 



1. Dioxybenzenes. 

 C 6 H 6 2 = C 6 H 4 (OH) 2 . 



a. Hydroquinone (Ortho-dioxybenzene). Is pro 

 duced from quinic acid by destructive distillation ; or 

 by the addition of lead superoxide to its aqueous solu 

 tion ; by treating arbutine (see Glucosides) with dilute 

 sulphuric acid; by heating orthoiodophenol (p. 293) 

 with caustic potassa at 180; and is prepared most 

 readily by treating quinone with sulphurous or hydrio- 

 dic acid. 



Colorless prisms. Easily soluble in water, alcohol, and 

 ether ; fusing point, 177.5. When carefully heated it 

 is sublimable. Combines with sulphuretted hydrogen 



