Synthesis of pharmaceutical intermediate 2,4,6-trihydroxybenzoic acid

2,4,6-trihydroxybenzoic acid is an important pharmaceutical intermediate. 2,4,6-trihydroxybenzoic acid is a white powder with a flash point of 164.481 ° C, a boiling point of 373 ℃, and a relative density of 1.924 g / cm3. It is irritating to eyes, respiratory system and skin. In case of contact with eyes, please wash with plenty of water immediately and consult doctor. Wear appropriate gloves, goggles or mask during operation.

The preparation process is as follows:
(1) Synthetic reaction
The anhydrous ions, sodium bicarbonate and phloroglucinol were respectively put into the synthesis reactor, and then the material mouth was closed, the stirring was started, and the air in the reactor was replaced by CO2 gas. After reaching the standard, the temperature was raised rapidly, and the reaction was held for 4 h. After the reaction, the temperature was rapidly lowered, the pressure was released and the material was drained, and the mother liquor entered the next acid precipitation operation.
(2) Acid precipitation
The synthetic mother liquor and dilute sulfuric acid are pressed into the acid precipitation kettle at the same time. The stirring is started to adjust the pH. after the jacket is cooled, stirring intermittently and standing for 2 h, the crude product of 2,4,6-trihydroxybenzoic acid centrifuged is washed with deionized water, and the crude product enters the refining operation.
(3) Crude refining
Add quantitative deionized water to the recrystallization reactor and raise the temperature. Add appropriate crude 2,4,6-trihydroxybenzoic acid. After dissolving completely, cool down with ice water quickly. After standing for a period of time, centrifugation washing and vacuum drying the wet product for 3 h to obtain the final product.