Chemistry:Gentisic acid
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| Preferred IUPAC name
2,5-Dihydroxybenzoic acid | |
| Other names
DHB
5-Hydroxysalicylic acid Gentianic acid Carboxyhydroquinone 2,5-Dioxybenzoic Acid Hydroquinonecarboxylic acid | |
| Identifiers | |
3D model (JSmol)
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PubChem CID
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| Properties | |
| C7H6O4 | |
| Molar mass | 154.12 g/mol |
| Appearance | white to yellow powder |
| Melting point | 204 °C (399 °F; 477 K)[3] |
| Acidity (pKa) | 2.97[2] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
 verify (what is   ?)
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| Infobox references | |
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]
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]
Reactions
In the presence of the enzyme gentisate 1,2-dioxygenase, gentisic acid reacts with oxygen to give maleylpyruvate:
- 2,5-dihydroxybenzoate + O2 [math]\displaystyle{ \rightleftharpoons }[/math] maleylpyruvate
Applications
As a hydroquinone, gentisic acid is readily oxidised and is used as an antioxidant excipient in some pharmaceutical preparations.
In the laboratory, it is used as a sample matrix in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry,[9] and has been shown to conveniently detect peptides incorporating the boronic acid moiety by MALDI.[10]
References
- ↑ Gentisic acid - Compound Summary, PubChem.
- ↑ Haynes, p. 5.91
- ↑ Haynes, p. 3.190
- ↑ Levy, G; Tsuchiya, T (1972-08-31). "Salicylate accumulation kinetics in man". New England Journal of Medicine 287 (9): 430–2. doi:10.1056/NEJM197208312870903. PMID 5044917.
- ↑ Tian, Rong-Rong; Pan, Qiu-Hong; Zhan, Ji-Cheng; Li, Jing-Ming; Wan, Si-Bao; Zhang, Qing-Hua; Huang, Wei-Dong (2009). "Comparison of Phenolic Acids and Flavan-3-ols During Wine Fermentation of Grapes with Different Harvest Times". Molecules 14 (2): 827–838. doi:10.3390/molecules14020827.
- ↑ Hudnall, Phillip M. (2005) "Hydroquinone" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. Wiley-VCH, Weinheim. doi:10.1002/14356007.a13_499.
- ↑ Behrman, E.J. (1988). Organic Reactions, Volume 35. New York: John Wiley & Sons Inc.. p. 440. ISBN 978-0471832539. https://books.google.com/books?id=sfjdPwAACAAJ&q=0471832537.
- ↑ Schock, R. U. Jr.; Tabern, D. L. (1951). "The Persulfate Oxidation of Salicylic Acid. 2,3,5-Trihydroxybenzoic Acid". The Journal of Organic Chemistry 16 (11): 1772–1775. doi:10.1021/jo50005a018.
- ↑ "2,5-Dihidroxybenzoic acid: a new matrix for laser desorption-ionization mass spectrometry". Int. J. Mass Spectrom. Ion Process. 72 (111): 89–102. 1991. doi:10.1016/0168-1176(91)85050-V. Bibcode: 1991IJMSI.111...89S.
- ↑ Crumpton, J.; Zhang, W.; Santos, W. L. (2011). "Facile Analysis and Sequencing of Linear and Branched Peptide Boronic Acids by MALDI Mass Spectrometry". Analytical Chemistry 83 (9): 3548–3554. doi:10.1021/ac2002565. PMID 21449540.
Cited sources
- Haynes, William M., ed (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. ISBN 9781498754293.
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