Method of producing glucofrangulin of technical purity

Claim 1

A CONTINUOUS METHOD FOR PRODUCING TECHNICALY PURE GLUCOFRANGULIN FROM AN AQUEOUS ALCOHOLIC RAW EXTRACT OF ALDER BUCKTHORN BARK CONTAINING IMPURITIES COMPRISING FRANGULIN AND EMODIN WHICH CONSISTS ESSENTIALLY OF THE STEPS OF: A. PRECIPITATING IMPURITIES POORLY SOLUBLE IN WATER FROM SAID RAW EXTRACT BY TREATING IT WITH WATER; B. REMOVING SAID IMPURITIES POORLY SOLUBLE IN WATER BY FILTRATION TO PRODUCE A PREPURIFIED GLUCOFRANGULIN CONTAINING RAW EXTRACT; C. SUBJECTING SAID PREPURIFIED RAW EXTRACT TO COUNTERCURRENT LIQUID-LIQUID EXTRACTION WITH A BINARY SOLVENT SYSTEM CONSISTING OF (1) AN ORGANIC PHASE CONSISTING OF WATERSATURATED BUTANOL OR HIGHER ALIPHATIC ALCOHOL, METHYL ETHYL KETONE, METHYLISOBUTYL KETONE OR WATER SATURATED MIXTURE THEREOF AND (2) AN AQUEOUS PHASE SATURATED WITH THE ORGANIC PHASE ADJUSTED TO A PH OF ABOUT 5.5, TO EFFECT PREFERENTIAL TRANSFER OF SAID GLUCOFRANGULIN INTO SAID ORGANIC PHASE; D. COUNTERCURRENTLY CONTACTING THE THUS OBTAINED GLUCOFRANGULIN-CONTAINING ORGANIC PHASE FROM STEP (C) WITH AN AQUEOUS PHASE ADJUSTED TO A PH OF ABOUT 4 TO EFFECT PREFERENTIAL TRANSFER OF GLUCOFRANGULIN FROM SAID ORGANIC PHASE INTO SAID AQUEOUS PHASE; E. EVAPORATING SAID GLUCOFRANGULIN-CONTAINING AQUEOUS PHASE FROM STEP (D) TO RECOVER GLUCOFRANGULIN OF TECHNICAL PURITY; F. COUNTERCURRENTLY CONTACTING THE ORGANIC PHASE FROM STEP (D) WITH AN AQUEOUS PHASE ADJUSTED TO PH ABOUT 6.5 OR ABOVE, TO EFFECT PREFERENTIAL TRANSFER OF IMPURITIES INTO SAID AQUEOUS PHASE WITH RETENTION OF GLUCOFRANGULIN IN SAID ORGANIC PHASE; G. DISCARDING SAID AQUEOUS PHASE FROM STEP (F); H. EVAPORATING SAID ORGANIC PHASE FROM STEP (F) TO RECOVER ORGANIC SOLVENT THEREFROM, THEREBY PRODUCING A RESIDUECONTAINING GLUCOFRANGULIN, EMODIN AND FRANGULIN AND I. ADDING SAID RESIDUE OF STEP (H) ALONG WITH A NEW PORTION OF PREPURIFIED RAW EXTRACT TO STEP (C).