IV. ANTHRACENE-DERIVATIVES. 



ANTHRACENE, the substance from which the hod-ies 

 of this group are derived, has a chemical constitution 

 similar to that of benzene and naphthalene. It bears 

 the same relation to naphthalene that the latter bears 

 to benzene. It may be considered as a combination of 

 three benzene-rings, of which each one has two carbon 

 atoms in common with one or both the others : 



CH:CH.C.CH:C.CH:CH 

 CH:CH.C.CH:C.CH:Oa 



Anthracene. 

 C 14 H 10 . 



Formation. By dry distillation of anthracite coal ; 

 hence contained in coal-tar. By heating benzyl chlo- 

 ride (p. 274) with water at 190, together with liquid 

 ditolyl (p. 282) and benzylic ether (p. 313). 



Preparation. From those portions of coal-tar, that 

 boil at high temperatures, by means of repeated dis- 

 tillations, pressing, and recrystallizing from benzene. 

 To obtain it perfectly pure and colorless, it must be 

 sublimed at as low a temperature as possible, best by 

 heating it until it begins to boil, and then blowing a 

 strong current of air over it by means of a pair of bel- 

 lows. Or the solution in hot benzene is bleached in 

 direct sunlight. 



Properties. Colorless, monoclinate plates ; when per- 

 fectly pure exhibiting a beautiful blue fluorescence ; 

 fusing point, 213; boiling point, somewhat above 



