CPC C07D 311/32 (2013.01) [C07D 311/40 (2013.01)] | 20 Claims |
1. A preparation method of dihydroquercetin, comprising the steps of:
adjusting the alkalinity of a water reaction solvent with an alkalizing reagent, to obtain an alkaline aqueous solution;
dissolving quercetin dihydrate in the alkaline aqueous solution, and adding an oxygen-containing sulfite binary combined reducing agent to carry out reduction reaction, to obtain an endpoint reduction reaction solution;
diluting the endpoint reduction reaction solution with water, and then acidizing, aging, and filtering a resultant to obtain a filtrate and a filter cake;
subjecting the filtrate to extraction, washing, drying, and vacuum concentration to obtain a concentrated crude product; and
repeatedly crystallizing the concentrated crude product to obtain the dihydroquercetin,
wherein the oxygen-containing sulfite binary combined reducing agent is selected from the group consisting of a binary combination of sodium hydrosulfite and sodium pyrosulfite and a binary combination of sodium hydrosulfite and sodium bisulfite.
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