Gentisic acid[1]
Skeletal formula of gentisic acid
Space-filling model of the gentisic acid molecule
Names
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)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.007.017
KEGG
UNII
  • InChI=1S/C7H6O4/c8-4-1-2-6(9)5(3-4)7(10)11/h1-3,8-9H,(H,10,11) checkY
    Key: WXTMDXOMEHJXQO-UHFFFAOYSA-N checkY
  • InChI=1/C7H6O4/c8-4-1-2-6(9)5(3-4)7(10)11/h1-3,8-9H,(H,10,11)
    Key: WXTMDXOMEHJXQO-UHFFFAOYAO
  • O=C(O)c1cc(O)ccc1O
Properties
C7H6O4
Molar mass 154.12 g/mol
Appearance white to yellow powder
Melting point 204 °C (399 °F; 477 K)[2]
Acidity (pKa) 2.97[3]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)
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 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

  1. ↑ Gentisic acid - Compound Summary, PubChem.
  2. ↑ Haynes, p. 3.190
  3. ↑ Haynes, p. 5.91
  4. ↑ 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.
  5. ↑ 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. PMC 6253884.
  6. ↑ 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.
  7. ↑ Behrman, E.J. (1988). Organic Reactions, Volume 35. New York: John Wiley & Sons Inc. p. 440. ISBN 978-0471832539.
  8. ↑ 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.
  9. ↑ Strupat K, Karas M, Hillenkamp F (1991). "2,5-Dihidroxybenzoic acid: a new matrix for laser desorption-ionization mass spectrometry". Int. J. Mass Spectrom. Ion Process. 72 (111): 89–102. Bibcode:1991IJMSI.111...89S. doi:10.1016/0168-1176(91)85050-V.
  10. ↑ 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. PMC 3090651. PMID 21449540.

Cited sources

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