P-hydroxybenzoic acidIt is a widely used organic synthetic raw material, especially its esters, including methyl p-hydroxybenzoate (Nipagin a), ethyl ester (Nipagin b), propyl ester, butyl ester, isopropyl ester and isobutyl ester. It can be used as a food additive for soy sauce, vinegar, cool drinks (except soft drinks), fruit flavoring agents, fruits and vegetables, pickled products, etc. it is also widely used in food, cosmetics, medicine, preservatives, fungicides and fungicides. P-hydroxybenzoic acid is also used as an intermediate of dyes and pesticides. It is used to synthesize organophosphorus insecticides gyap and CYP in pesticides; A color developing agent used in the synthesis of heat sensitive dyes in the dye industry; It can also be used as raw material of plasticizer in color film, synthetic oil soluble coupler "538" and nylon 12. In addition, it is also used in liquid crystal polymers and plastics.

    P-hydroxybenzoic acid can also be used as antiseptic and bactericide. Pharmacological experiments showed that it had obvious protective effect on Cobra poisoning in mice. This product can inhibit the growth of mold. It can react with alcohol, propanol, butanol and other alcohols to produce various esters. It is an excellent preservative. This product can also be used as antiseptic and insecticide in dyeing, organic synthesis industry and other fields. P-hydroxyphenyl acid naturally exists in the leaves of Platycodon grandiflorum, azalea and Rhododendron minor. Therefore, it has a wide range of sources and uses, and is a very important raw material for organic synthesis.