Gentisic acid

Gentisic acid ^[1]

Names
Preferred IUPAC name 2,5-Dihydroxybenzoic acid
Other names DHB 5-Hydroxysalicylic acid Gentianic acid Carboxyhydroquinone 2,5-Dioxybenzoic Acid Hydroquinonecarboxylic acid
Identifiers
CAS Number	490-79-9  Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:17189  Y
ChEMBL	ChEMBL1461  Y
ChemSpider	3350  Y
ECHA InfoCard	100.007.017
KEGG	C00628  Y
PubChem CID	3469
UNII	VP36V95O3T  Y
CompTox Dashboard (EPA)	DTXSID4060078
InChI InChI=1S/C7H6O4/c8-4-1-2-6(9)5(3-4)7(10)11/h1-3,8-9H,(H,10,11) Y Key: WXTMDXOMEHJXQO-UHFFFAOYSA-N Y 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
SMILES O=C(O)c1cc(O)ccc1O
Properties [2]
Chemical formula	C7H6O4
Molar mass	154.121 g·mol−1
Appearance	white to yellow powder
Melting point	204 °C (399 °F; 477 K)
Solubility in water	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	2,3-Dihydroxybenzoic acid 2,4-Dihydroxybenzoic acid 2,6-Dihydroxybenzoic acid 3,4-Dihydroxybenzoic acid 3,5-Dihydroxybenzoic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y  verify  (what is  YN ?) 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 and oxygen, gentisic acid undergoes a ring-opening reaction to give maleylpyruvate:^{[ citation needed ]}

C₇H₆O₄ + O₂ ⇌ C₇H₆O₆

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. ^{[9] [10]}

References

1. "Gentisic acid - Compound Summary". PubChem.
2. Haynes, William M., ed. (2016). "3". CRC Handbook of Chemistry and Physics (PDF) (97th ed.). CRC Press. p. 190. ISBN   9781498754293.
3. Haynes, William M., ed. (2016). "5". CRC Handbook of Chemistry and Physics (PDF) (97th ed.). CRC Press. p. 91. ISBN   9781498754293.
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. "Hydroquinone". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_499. ISBN   978-3-527-30673-2.
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.