4-Hydroxybenzoic Acid (4-HBA)

4-Hydroxybenzoic acid is a monohydroxybenzoic acid, a phenolic derivative of benzoic acid. It is a white crystalline solid that is slightly soluble in water and chloroform but more soluble in polar organic solvents such as alcohols and acetone. 4-Hydroxybenzoic acid is primarily known as the basis for the preparation of its esters, known as parabens, which are used as preservatives in cosmetics and some ophthalmic solutions. It is isomeric with 2-hydroxybenzoic acid, known as salicylic acid, a precursor to aspirin. p-Hydroxybenzoic acid glucoside can be found in mycorrhizal and non-mycorrhizal roots of Norway spruces (Picea abies). Violdelphin is ananthocyanin, a type of plant pigments, found in blue flowers and incorporating two p-hydroxy benzoic acid residues, one rutinoside and two glucosides associated with a delphinidin.