410 PYRENE. 



Anthracenecarbonic Acid. 

 C 15 H 10 2 = C 14 H 9 .CO.OH. 



Preparation. By heating anthracene with phosgene 

 in sealed tubes for twelve hours at 200, dissolving the 

 product in a solution of sodium carbonate, and precipi- 

 tating with hydrochloric acid. 



Properties. Long bright-yellow needles of a silky 

 lustre. Fuses at 206, with decomposition. Almost 

 insoluble in cold water, difficultly in boiling water, 

 easily soluble in alcohol. Heated alone or with soda- 

 lime, it is resolved into anthracene and carbonic acid. 

 When its solution in glacial acetic acid containing 

 chromic acid is gently warmed it is converted into 

 anthraquinone. 



Most of its salts are soluble in water and alcohol. 



In connection with this group, a few hydrocarbons 

 that are not so well known, will here be described. 



Pyrene, C 16 H 10 (isomeric with diacetenylphenyl, p. 

 379). Is contained in those portions of coal-tar that 

 boil at a high temperature. Those hydrocarbons that 

 boil higher than anthracene are extracted by means of 

 carbon bisulphide. Crude chrysene (p. 411) is thus left 

 behind, while pyrene and other hydrocarbons are dis- 

 solved. In order to purify the pyrene, the carbon 

 bisulphide is distilled off, the residue dissolved in alco- 

 hol, and mixed with an alcoholic solution of picric 

 acid. Red crystals of a compound of pyrene with 

 picric acid are deposited, which, after repeated recrys- 

 tallizations from alcohol, are decomposed with ammo- 

 nia. Colorless lamine ; fusing point, 142 ; but slightly 

 soluble in cold alcohol, more readily in hot alcohol, 

 very easily soluble in benzene, ether, and carbon bisul- 

 phide. 



Nitric acid readily converts it into substitution-pro- 

 ducts ; bromine yields substitution- and addition-pro- 

 ducts. Heated with potassium bichromate and dilute 

 sulphuric acid, it is converted into pyrenequinone. 



