METHOD OF ISOLATING BETULINOL Russian patent published in 1999 - IPC

FIELD: isolation of natural compounds. SUBSTANCE: invention relates to chemical processing of birch bark. Betulinol, e.g. lup-20[29]-en-3β,28-diol, with high content of principal substance is obtained by extraction of birch bark with high-boiling hydrocarbon solvent (e.g. white spirit). Method is distinguished by that extract is treated with concentrated aqueous solution of sodium hydroxide, resulting precipitate of sodium derivatives of fatty and triterpenic acids, tannins, and flavonoids is separated, and supernatant is then cooled to precipitate betulinol. Alkali treatment increases level of principal substance in betulinol products from 76 to 88-90%. Single-step recrystallization from C₂-C₄-alcohols or their acetates gives 97-99.5% betulinol. Expenses can be reduced if white spirit mother solution is reused for extraction of next portion of birch bark. Wet birch bark should be extracted under azeotropic drying conditions. EFFECT: optimized preparation conditions and increased purity of product. 3 cl, 2 tbl, 12 ex