Method 1: Using birch bark as raw material, the extraction and purification process of betulin in birch bark was studied, and this process was suitable for the scale-up production of medicine. Crush the birch bark, extract with 10 times the amount of 95% ethanol under reflux for 5 hours, filter, and extract the filter residue with 8 times the amount of 95% ethanol under reflux for 3 hours, combine the filtrates, recover ethanol, pass through a diatomaceous earth column, and wash with ethyl acetate Ethyl acetate was recovered from the eluate to dryness, and 15 times of 95% ethanol was added to heat to dissolve, then cooled below 0~C, filtered, and dried, and the content of the dry product was above 98%.
Method 2: a method for preparing high-purity betulin, comprising:
1) The pulverized white birch bark is extracted by heating and refluxing with an aqueous ethanol solution, the extract is collected, then the extract is concentrated, the concentrate is cooled, the crude betulin solid is precipitated, and the crude product I is obtained by filtration;
2) Dissolving the crude betulin alcohol I obtained in step (1) in an aqueous ethanol solution, heating and stirring to dissolve, filtering while hot to remove insoluble impurities, adding an aqueous alkali solution, solid precipitation, cooling, and filtering the solid to obtain crude product II;
3) Dissolve the crude betulin alcohol II obtained in step (2) in an aqueous ethanol solution, heat to dissolve, filter to remove insoluble impurities, collect the filtrate, place and cool to precipitate crystals, filter to obtain a solid, and dry to obtain betulin with a purity greater than or equal to 99%. alcohol.
