4-Hydroxybenzoic acid

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4-Hydroxybenzoic acid
IUPAC name	4-Hydroxybenzoic acid
Other names	p-Hydroxybenzoic acid para-Hydroxybenzoic acid
Identifiers
CAS number	[99-96-7]
SMILES	OC1=CC=C(C(O)=O)C=C1
Properties
Molecular formula	C7H6O3
Molar mass	138.12 g/mol
Density	1.46 g/cm³
Melting point	214-217 °C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

4-Hydroxybenzoic acid, or p-hydroxybenzoic acid, is a phenolic derivative of benzoic acid. It is a white crystalline solid that is slightly soluble in water and chloroform, but soluble to extremely soluble in alcohols, ether, 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.

[edit] Production

4-Hydroxybenzoic acid is produced commercially from potassium phenoxide and carbon dioxide in the Kolbe-Schmitt reaction. It can also be produced in the laboratory by heating potassium salicylate with potassium carbonate to 240 °C, followed by treating with acid.^[1]

[edit] See also

The closely related 2-hydroxybenzoic acid is known as salicylic acid, a precursor to aspirin.

[edit] References

1. ^ Organic Syntheses, p-hydroxybenzoic acid, Coll. Vol. 2, p. 341 (1943).