3, 4-dihydroxybenzoic acid, also known as protocatechuic acid, is a needle-like crystal soluble in hot water, ethanol, and ether. The color varies from white to light brown, depending on purity. 3,4-dihydroxybenzoic acid breaks down in boiling water and releases carbon dioxide. Aqueous solutions of 3, 4-dihydroxybenzoic acid turn dark red on sodium bicarbonate. If iron is encountered, it turns green.
The synthesis process of 3, 4-dihydroxybenzoic acid can be obtained from vanillin by alkali melting oxidation demethylation and acidification treatment. Piperaldehyde can also be used as raw material to obtain piperic acid by oxidation with potassium permanganate, and then 3, 4-dihydroxy benzoic acid by hydrolysis with aluminum trichloride.
3, 4-dihydroxybenzoic acid has been widely used in the medical field because of its broad-spectrum antibacterial activity. In vitro experiments, we found that 3, 4-dihydroxybenzoic acid can play different degrees of antibacterial effects on Shigella, Typhoid, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, alkali producing bacillus and Staphylococcus aureus.
