3, 4-dihydroxybenzoic acid, also known as protocatechuic acid, is a needle-like crystal that dissolves in hot water, ethanol, and ether and varies in color from white to light brown, depending on its purity. 3,4-dihydroxybenzoic acid, which breaks down in boiling water and releases carbon dioxide, turns dark red when it encounters sodium bicarbonate and green when it encounters ferric chloride.
As for the synthesis process of 3, 4-dihydroxybenzoic acid, it can be obtained from vanillin as raw material through alkaline melting oxidation demethylation, and then through acidification treatment. Piperaldehyde can also be used as raw material, using potassium permanganate for oxidation to obtain piperic acid, and then through aluminum chloride hydrolysis to obtain 3, 4-dihydroxy benzoic acid. 3, 4-dihydroxybenzoic acid can be mainly used in the medical field to play its antibacterial role. Through in vitro tests, we found that 3, 4-dihydroxybenzoic acid can play different degrees of antibacterial effect on dysentery bacillus, Typhoid bacillus, Escherichia coli, Pseudomonas aeroginosa, Bacillus subtilis, alkali producing bacillus, Staphylococcus aureus and so on.