3,4-dihydroxybenzoic acid is a phenolic acid found naturally in fruits, vegetables, nuts, tea, brown rice, and some Chinese herbs. As commodities, it appears as a white to brown crystalline powder that discolors when exposed to air, breaks down in boiling water, and releases carbon dioxide, Aqueous solutions of 3,4-dihydroxybenzoic acid turn green on ferric chloride and red on sodium bicarbonate.
So how can 3,4-dihydroxybenzoic acid be prepared? Vanillin can be prepared as raw material. 3,4-dihydroxybenzoic acid can be obtained by acidizing vanillin after demethylation by alkaline melting. Piperaldehyde can also be used as a raw material for preparation. 3,4-dihydroxybenzoic acid can be obtained by oxidizing it to piperic acid with potassium permanganate and hydrolyzing it with aluminum chloride.
3,4-dihydroxybenzoic acid is mainly used as pharmaceutical intermediates in the medical field and can exert its antibacterial effects. It was found that 3,4-dihydroxybenzoic acid has different antibacterial effects on Bacillus dysenteriae, Bacillus typhi, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, allogenic Bacillus and Staphylococcus aureus.
