3,4-dihydroxybenzoic acid is a kind of phenolic acid, which naturally exists in a variety of fruits and vegetables. It is water-soluble and has biological activity. Procatechuic acid is also an effective active ingredient in traditional Chinese medicine such as Hiborium multiflorus and Salvia miltiorrhiza. 3,4-dihydroxybenzoic acid can not only play the role of analgesia, bacteriostasis, reduce heart oxygen consumption, anti-platelet agglutination, slow heart rate, improve myocardial oxygen resistance, but also can protect nerves, anti-tumor, anti-oxidation and other functions.
At present, 3,4-dihydroxybenzoic acid on the market is generally white to brown crystalline powder in appearance, with the molecular formula C7H6O4, molecular weight 154.12, CAS registration number 99-50-3. 3,4-dihydroxybenzoic acid changes color in the air, and it also appears blue-green if encountered in an aqueous solution of ferric chloride. It should be noted that when storing 3,4-dihydroxybenzoic acid, it should be sealed and stored in a shading, cool and dry environment.