Studies on the Purification of Anthracene; Determination and Use of Segregation Coefficients

Zone melting and normal freezing have been used in a study of the purification of anthracene. Of thirteen impurities concentrated by zone melting and gradient sublimation and isolated by chromatography, twelve have been identified as naphthalene, biphenyl, acenaphthene, fluorene, 9, 10-dihydroanthracene, carbazole, phenanthrene, 2-methylanthracene, anthraquinone, pyrene, chrysene and tetracene. Effective segregation coefficients were measured at various rates of crystallization for fluorene, phenanthrene, carbazole, anthraquinone and tetracene. The effect of stirring on segregation was studied; by reducing the extent of constitutional supercooling, stirring gives greater segregation and smoother concentration profiles in normally frozen ingots.