Gallic acid
291767
200909192
2008-03-25T22:14:16Z
Hellbus
290570
{{Chembox new
| Name = Gallic acid
| ImageFile = Gallic acid.svg
<!-- | ImageSize = 150px -->
| ImageName = Gallic acid
| IUPACName = 3,4,5-hydroxybenzoic acid
| OtherNames = Gallic acid
| Section1 = {{Chembox Identifiers
| SMILES = Oc1cc(cc(O)c1O)C(O)=O
| CASOther = [149-91-7] (Anhydrous)<br />[5995-86-8] (Monohydrate)
}}
| Section2 = {{Chembox Properties
| Formula = C<sub>7</sub>H<sub>6</sub>O<sub>5</sub>
| MolarMass = 170.12 g/mol
| Appearance = White, yellowish-white, or<br />pale fawn-colored crystals.
| Density = 1.7 g/cm<sup>3</sup> (anhydrous)
| Solubility = 1.1g/100ml water @ 20°C (anhydrous)<br />1.5g/100ml water @ 20°C (monohydrate)
| MeltingPt = 250°C (523 K)
| BoilingPt = (? K)
| pKa = COOH: 4.5, OH: 10.
}}
| Section3 = {{Chembox Structure
| CrystalStruct =
| Dipole =
}}
| Section7 = {{Chembox Hazards
| ExternalMSDS = [http://bulkpharm.mallinckrodt.com/_attachments/msds/G0806.htm External MSDS]
| MainHazards = Irritant
}}
| Section8 = {{Chembox Related
| Function = [[phenol]]s,<br />[[carboxylic acid]]s
| OtherFunctn =
| OtherCpds = [[Benzoic acid]], [[Phenol]]
}}
}}
'''Gallic acid''' is an [[organic acid]], also known as 3,4,5-trihydroxy[[benzoic acid]], found in [[gallnut]]s, [[sumac]], [[witch hazel]], [[tea]] leaves, [[oak]] [[bark]], and other [[plant]]s. The chemical formula is [[carbon|C]]<sub>6</sub>[[hydrogen|H]]<sub>2</sub>([[oxygen|OH]])<sub>3</sub>COOH. Gallic acid is found both free and as part of [[tannin]]s. [[Salts]] and [[ester]]s of gallic acid are termed [[gallate]]s. Despite its name, it does not contain [[gallium]].
Gallic acid is commonly used in the pharmaceutical industry.{{Fact|date=March 2008}} It is used as a [[standard]] for determining the [[phenol]] content of various analytes by the [[Folin-Ciocalteau assay]]; results are reported in ''gallic acid equivalents''.<ref>{{cite web | author = Andrew Waterhouse | title = Folin-Ciocalteau Micro Method for Total Phenol in Wine | publisher = [[UC Davis]] | url = http://waterhouse.ucdavis.edu/phenol/folinmicro.htm}}</ref> Gallic acid can also be used to synthesize the hallucinogenic alkaloid [[mescaline]], also known as 3,4,5-trimethoxyphenethylamine.{{Fact|date=March 2008}}
Gallic acid was one of the substances used by [[Angelo Mai]] among other early investigators of [[palimpsest]]s to clear the top layer of text off and reveal hidden manuscripts underneath. Mai was the first to employ it, but did so "with a heavy hand," often damaging manuscripts for future study.{{Fact|date=March 2008}}
==See also==
*[[Pyrogallol]]
*[[Syringol]]
*[[Syringaldehyde]]
==References==
{{citationstyle|date=September 2007}}
*LD Reynolds and NG Wilson, “Scribes and Scholars” 3rd Ed. Oxford: 1991. pp193–4.
<references/>
==External links==
*[http://www.henriettesherbal.com/eclectic/kings/acidum-gall.html King's American Dispensatory (1898) entry on Gallic acid]
[[Category:Benzoic acids]]
[[Category:Phenols]]
[[Category:Astringent flavors]]
[[cs:Kyselina gallová]]
[[de:Gallussäure]]
[[fr:Acide gallique]]
[[it:Acido gallico]]
[[nl:Galluszuur]]
[[ja:没食子酸]]
[[pl:Kwas galusowy]]
[[ru:Галловая кислота]]
[[fi:Gallushappo]]
[[zh:没食子酸]]