| 摘要 |
A method to purify crude diacerein via the use of toluene which consists of: dissolving crude diacerein in about 13 times the volume of dry diacerein of a 1:1 acetone/water mixture; adjusting the pH at 6.6-7.2, preferably 7.0-7.2, with a solution of a tertiary amine in acetone; a trialkylamine with C1-4 alkyl groups may be used as a tertiary amine, preferably selected from the group: trimethylamine, triethylamine, tripropylamine, methyldiethylamine, diethylpropylamine, among which triethylamine is most preferred; stirring until the diacerein is completely dissolved; adding an organic water immiscible-solvent and stir; performing between 5 and about 15 repeated extractions with the organic solvent and each time separating the organic phase; diacerein is crystallized in the acetone/water phase when changing the pH from neutral to acid with a strong mineral acid selected from hydrochloric, sulphuric and phosphoric acid; the crystallized product is centrifuged or filtered, washed with water and dried. Following this method diacerein is obtained under a 90-93% yield, an average purity of 99.17%, a content of aloe-emodin of 7-10 ppm and a content of chromium of 20-25 ppm.
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