3, 4-dihydroxybenzoic acid is a needle-like crystal, soluble in hot water, ethanol, and ether, and varies in color from white to light brown, depending on its purity. 3,4-dihydroxybenzoic acid not only breaks down in boiling water, but also releases carbon dioxide. When aqueous 3, 4-dihydroxybenzoic acid meets sodium bicarbonate, it changes color, turning dark red, and green when ferric chloride meets.
There are many ways to synthesize 3, 4-dihydroxybenzoic acid. For example, vanillin can be used as a raw material, through alkaline melting, oxidation and demethylation, and then through acidification, 3, 4-dihydroxybenzoic acid can be obtained. If piperanol is used as raw material, 3, 4-dihydroxybenzoic acid can also be synthesized, which is oxidized with potassium permanganate and then hydrolyzed by aluminum trichloride to get 3, 4-dihydroxybenzoic acid. 3, 4-dihydroxybenzoic acid can be widely used in the medical field, because 3, 4-dihydroxybenzoic acid has a good antibacterial effect on dysentery bacillus, Typhoid bacillus, Escherichia coli, Pseudomonas aeruginosa, bacillus subtilis, alkali producing bacillus, staphylococcus aureus and other bacteria.
