4-Hydroxybenzoic acid 3626498 225384260 2008-07-13T11:48:04Z Rifleman 82 1255637 fix {{Chembox new | Name = 4-Hydroxybenzoic acid | ImageFile = 4-Hydroxybenzoic acid.svg | ImageSize = 75px | ImageName = 4-Hydroxybenzoic acid | IUPACName = 4-Hydroxybenzoic acid | OtherNames = ''p''-Hydroxybenzoic acid<br />''para''-Hydroxybenzoic acid | Section1 = {{Chembox Identifiers | CASNo = 99-96-7 | SMILES = OC1=CC=C(C(O)=O)C=C1 | PubChem = 135 }} | Section2 = {{Chembox Properties | Formula = C<sub>7</sub>H<sub>6</sub>O<sub>3</sub> | MolarMass = 138.12074 g/mol | Density = 1.46 g/cm³ | MeltingPt = 214-217 °C }} }} '''4-Hydroxybenzoic acid''', or ''p''-hydroxybenzoic acid, is a [[phenol]]ic derivative of [[benzoic acid]]. It is a white crystalline solid that is slightly soluble in water and [[chloroform]], but soluble to extremely soluble in [[alcohol]]s, [[diethyl ether|ether]], and [[acetone]]. 4-Hydroxybenzoic acid is primarily known as the basis for the preparation of its [[ester]]s, known as [[paraben]]s, which are used as preservatives in cosmetics. ==Production== 4-Hydroxybenzoic acid is produced commercially from potassium [[phenol|phenoxide]] and [[carbon dioxide]] in the [[Kolbe-Schmitt reaction]]. It can also be produced in the laboratory by heating [[salicylic acid|potassium salicylate]] with [[potassium carbonate]] to 240 °C, followed by treating with acid.<ref>[[Organic Syntheses]], [http://www.orgsyn.org/orgsyn/pdfs/CV2P0341.pdf p-hydroxybenzoic acid], Coll. Vol. 2, p. 341 (1943).</ref> ==See also== The closely related 2-hydroxybenzoic acid is known as [[salicylic acid]], a precursor to [[aspirin]]. ==References== {{reflist}} {{DEFAULTSORT:Hydroxybenzoic acid, 4-}} [[Category:Phenols]] [[Category:Benzoic acids]] [[Category:Monomers]] [[Category:Hydroxy acids]] {{phenol-stub}}