Separation and recovery of dibenzofuran of high purity is accomplished by distilling a coal tar fraction having boiling point range of 220.degree. to 300.degree. C. thereby producing a dibenzofuran fraction having a dibenzofuran content of not less than 30% by weight, a dibenzofuran/acenaphthene molar ratio of not less than 1.3, and a fluorene/dibenzofuran molar ratio of not more than 0.05, then introducing the dibenzofuran fraction obtained as described above into a continuous crystallization purification unit provided with a cooling zone for crystallization of the feed, a heating zone for melting the purified crystals, and a refining zone for enabling crystals being transferred from said cooling zone to said heating zone to come into counter current contact with a mass of molten crystals midway along the path between said two zones, and subjecting the dibenzofuran fraction to continuous crystallization purification therein.
The invention concerns a coal tar extract with reduced polycyclic aromatic hydrocarbon and benzo(a)pyrene content and a method for obtaining same using two sequentially linked distillation systems. The invention also concerns cosmetic and dermatological preparations containing said resulting coal tar extract.
Provided is a method of inhibiting estrogen activity by administering a biologically active amount of a substituted dibenzofuran or substituted dibenzodioxin.
