Salicylic Acid and Related Compounds

Abstract Salicylic acid, also known as o ‐hydroxybenzoic acid, appears early in the historical recognition of the identity and preparation of organic compounds. The extract of roots, bark, leaves, and fruit of many plants and trees contains the glucosides of methyl salicylate and other derivatives from which salicylic acid is easily derived by extraction and mild oxidation. The extract of willow bark was referenced by Hypocrites about 400 BC as a pain reliever, and the preparation and crude estimate of strength were cited in the first United States Pharmacopeia published in 1820. Related to salicylic acid as isomers are m ‐hydroxybenzoic acid and p ‐hydroxybenzoic acid. The three are commonly known as the monohydroxybenzoic acids, which share chemical reactions and are used in a broad range of applications from paper coatings and liquid crystal preparations to drugs. Salicylic acid and its derivatives have demonstrated activity as analgesics, antipyretics, and antiinflammatory agents; para‐substituted acids and esters have activity as preservatives for food.