Preparation
Take 140g of glycyrrhizic acid powder (glycyrrhizic acid content approximately 25% HPLC), add 1120ml of 95% edible ethanol, extract at 40℃ for 3 hours, filter to remove insoluble impurities, distill the filtrate to recover ethanol to obtain the extract, dry the extract at 100℃ in a water bath to obtain 118g of dry extract with a water content of no more than 20%; pulverize the dry extract and take 100g, add 300ml of 70% glacial acetic acid and 7ml of concentrated sulfuric acid, hydrolyze and acetylate under normal pressure, heat to 98-103℃, react for 2 hours, after hydrolysis and acetylation are completed, cool to room temperature, filter the precipitated solid, wash the filter cake with 250ml of 65% acetic acid, then wash with 200ml of ethanol, and finally wash with 300ml of water, dry at 100℃ to obtain 20.21g of crude acetylglycine with a purity of 88.2% (HPLC).
Take 20g of acetylglycyrrhetinic acid, add 300ml of water, add 5g of sodium hydroxide to adjust the pH to 13, hydrolyze under reflux at normal pressure for 4 hours, cool to room temperature, acidify the pH to 5.2 with hydrochloric acid, filter, wash the filter cake with pure water to remove inorganic salts, and dry at 100℃ to obtain 17.8g of crude glycyrrhetinic acid with a purity of 92.9% (HPLC). Dissolve the crude glycyrrhetinic acid in 214ml of 95% ethanol (v/v), add 25% (4.45g) of activated carbon for reflux decolorization, filter after reflux decolorization, recover the ethanol from the filtrate, precipitate the solid, and filter to obtain 16.4g of glycyrrhetinic acid with a purity of 98.2% (neutralization method). For further purification, recrystallize three times with 95% ethanol to obtain glycyrrhetinic acid product with a purity of 98% (HPLC), with total impurity peaks not exceeding 2% and single impurity peaks not exceeding 0.7%, fully complying with the European Pharmacopoeia standards.
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