400 QUINONES. 



4. Trioxynaphthalene. 

 C 10 H 8 3 = C IO H 5 (OH) 3 . 



Is formed by the action of tin and hydrochloric 

 acid on oxynaphthoquinone, and after the solution has 

 been freed from tin by sulphuretted hydrogen, it can 

 be extracted by means of ether. Yellow needles ; so- 

 luble in water, alcohol, and ether ; the solutions, which 

 are at first colorless, turn yellow and brown in the 

 air. Is a strong reducing agent, especially in alkaline 

 solution. 



C. QUINONES. 



Naphthoquinone, C 10 H 6 j Q>, is as yet not known. 



Only substitution-products and other derivatives of it 

 have been discovered. 



Dichlornaphthoquinone (Chloroxynaphthalene 

 chloride), C 10 H 4 C1 2 1 Q>. Is produced by the action of 



nitric acid on chlornaphthalene chloride. Can be most 

 easily prepared by treating naphthol or commercial 

 naphthalene yellow (see Dinitronaphthol p. 397) with 

 hydrochloric acid and potassium chlorate, or by the 

 addition of chromium oxichloride to a solution of 

 naphthalene in concentrated acetic acid. Golden-yel- 

 low needles ; fusing point, 189 ; insoluble in water, 

 but slightly in cold alcohol and in ether, more readily 

 in hot alcohol ; easily sublimable. Hot concentrated 

 nitric acid converts it into phtalic acid. Sulphurous 

 acid and hydriodic acid convert it into dichlordioxy- 

 naphthalene, C 10 H 4 C1 2 (OH) 2 , which crystallizes in reddish- 

 colored needles, that fuse at 135-140, and are recon- 

 verted into dichlornaphthoquinone by iron chloride. 

 Heated with two molecules phosphorus chloride at 180- 

 200, dichlornaphthoquinone is transformed into penta- 

 chlornaphthalene (p. 393). , 



Oxynaphthoquinone (Naphthalic acid), 

 C 10 H 5 (OH) | Q>. Is most readily obtained by heating 



