Gentisic acid
Chemical compound
From Wikipedia, the free encyclopedia
Gentisic acid is a dihydroxybenzoic acid. It is a derivative of benzoic acid and a minor (1%) product of the metabolic break down of aspirin, excreted by the kidneys.[4]
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| Names | |
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| Preferred IUPAC name
2,5-Dihydroxybenzoic acid | |
Other names
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| Identifiers | |
3D model (JSmol) |
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| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.007.017 |
| KEGG | |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties[2] | |
| C7H6O4 | |
| Molar mass | 154.121 g·mol−1 |
| Appearance | white to yellow powder |
| Melting point | 204 °C (399 °F; 477 K) |
| very soluble | |
| Solubility in ethanol | very soluble |
| Solubility in diethyl ether | very soluble |
| Solubility in acetone | soluble |
| Acidity (pKa) | 2.97[3] |
| Related compounds | |
Related compounds |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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It is also found in the African tree Alchornea cordifolia and in wine.[5]
Production
Gentisic acid is produced by carboxylation of hydroquinone.[6]
- C6H4(OH)2 + CO2 → C6H3(CO2H)(OH)2
This conversion is an example of a Kolbe–Schmitt reaction.
Alternatively the compound can be synthesized from salicylic acid via Elbs persulfate oxidation.[7][8]
Metabolism
In the presence of the enzyme gentisate 1,2-dioxygenase and oxygen, gentisic acid undergoes a ring-opening reaction to give 3-maleylpyruvic acid:[9]
This reaction has been used to detect gentisic acid with a whole-cell biosensor developed from a 3-maleylpyruvic acid-inducible gene expression system and the gentisate 1,2-dioxygenase gene from chemolithoautotrophic bacterium Cupriavidus necator.[10]
Applications
As a hydroquinone, gentisic acid is readily oxidised and is used as an antioxidant excipient in some pharmaceutical preparations.[citation needed]
In the laboratory, it is used as a sample matrix in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, and has been shown to conveniently detect peptides incorporating the boronic acid moiety by MALDI.[11][12]