Preparation of 3,4,5-Trimethoxybenzoic Acid from Aqueous Taratannin

Preparation of 3,4,5-Trimethoxybenzoic Acid from Aqueous Taratannin 

To a 50 gallon reactor containing 108 lbs. of aqueous taratannin (gallic acid content approximately 34.6 lbs), charge 72 lb of 50% NaOH and 90 lbs of dimethyl sulfate in portions over a 2-6 hour period while maintaining a temperature of 20°-40° C. Then, the reaction mixture is refluxed for 2-4 hours with 21 lbs of 50% NaOH. Upon cooling to 30°-60° C., the reaction mixture is treated with 45 lbs of dimethyl sulfate and 18 lbs of 50% NaOH over a 2-4 hour period. Then, after the addition of an additional 27 lbs of caustic, tbe reaction solution is refluxed for 2-4 hours. Upon completion of hydrolysis, the reaction mixture is cooled, acidified to 3-5 pH with concentrated hydrochloric acid to yield 36-37 lbs. of dried 3,4,5-trimetboxyben/oic acid in 84-86% yield. 

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