METHOD OF DISTILLATION FOR IMPROVEMENT OF PROCESS OF PREPARING PURE PRODUCT FROM CRUDE ANTHRACENE Russian patent published in 2002 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to a method of preparing pure products from crude anthracene by distillation and crystallization. Invention proposes to carry out a distillation for two stages. In the first distillation column a fraction of diphenyloxide and fluorine with boiling limit points 280-320 C is separated as a head product under normal pressure. To a vat residue from the first column by-side product of carbazole synthesis obtained by crystallization as carbazole residues are added and this mixture is fed in the second distillation column where phenanthrene-containing fraction is removed in head part and anthracene and carbazole fractions are removed from side flows and high-boiling fraction and part of added carbazole are removed from a vat residue. Obtained fractions containing anthracene, carbazole, phenanthrene and fluorene are subjected for the treatment, preferably by crystallization, from a polar solvent. Pure anthracene product comprising less about 600 ppm of diphenyloxide, pure fluorene product comprising maximally about 5 wt.% of anthracene and carbazole pure product comprising minimally about 94 wt.% of carbazole are obtained. Method provides decrease of diphenyloxide content and decreased loss of carbazole. EFFECT: improved method of distillation, significant improvement of quality of pure anthracene product, increased yield of carbazole. 8 cl, 2 dwg, 1 ex