3, 4-dihydroxybenzoic acid is a kind of organic compound naturally existing in the flue gas of rice flue-cured tobacco, Burley tobacco, Oriental flue-cured tobacco. The molecular formula is C7H6O4, the molecular weight is 154.12, CAS number is 99-50-3. 3,4-dihydroxybenzoic acid is a white to light brown needle-like crystal, soluble in hot water, ethanol, ether, slightly soluble in cold water, insoluble in benzene, it will not only decompose in boiling water, but also release carbon dioxide.
Vanillin and piperaldehyde can be used to prepare 3, 4-dihydroxybenzoic acid. Using vanillin as raw material, 3, 4-dihydroxybenzoic acid can be obtained by alkali melting oxidation demethylation and acidification. Using piperaldehyde as raw material, it can be oxidized with potassium permanganate to obtain piperic acid, and then hydrolyzed with aluminum trichloride to obtain 3, 4-dihydroxybenzoic acid.
It is understood that at present, 3, 4-dihydroxybenzoic acid is mainly used as dye intermediates, pharmaceutical intermediates and analytical reagents in coatings, medicine, chemical, biological and other fields.
3, 4-dihydroxybenzoic acid should avoid contact with strong oxidizer and alkali during storage, and should not be mixed with oxidizer and strong acid for storage or transportation. It is recommended to store 3, 4-dihydroxybenzoic acid in a cool, dry, ventilated room, and away from fire and heat sources, also need to be equipped with corresponding leakage containers, explosion-proof lights and ventilation facilities.