3,4-dihydroxybenzoic acid, also known as procatechuic acid, is a phenolic acid that naturally occurs in many fruits and vegetables and is water-soluble. It is also an active ingredient in many traditional Chinese medicines such as hibiscus hibiscus and salvia miltiorrhiza. 3,4-dihydroxybenzoic acid can not only play the role of analgesia, bacteriostasis, reduce the heart oxygen consumption, anti-platelet agglutination, slow down the heart rate, improve the myocardial oxygen resistance, but also play the role of nerve protection, anti-tumor, anti-oxidation and so on.
Currently, 3,4-dihydroxybenzoic acid on the market is usually a white to brown crystalline powder with a discoloration when exposed to air, and a blue-green color if encountered with an aqueous solution of ferric chloride. The molecular formula C7H6O4, molecular weight 154.12, CAS accession number 99-50-3, note that we need to seal 3,4-dihydroxybenzoic acid and keep it in a dark, cool and dry environment.