Gentisic acid[ 1] Names Preferred IUPAC name 2,5-Dihydroxybenzoic acid
Other namesDHB
Identifiers 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)
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
Properties C7 H6 O4 Molar mass 154.12 g/mol Appearance white to yellow powder Melting point 204 °C (399 °F; 477 K)[ 3] Acidity (pK a )2.97[ 2] Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
Chemical compound
Gentisic acid is adihydroxybenzoic acid . It is a derivative ofbenzoic acid and a minor (1%) product of the metabolic break down ofaspirin , excreted by the kidneys.[ 4]
It is also found in the African treeAlchornea cordifolia wine .[ 5]
Gentisic acid is produced by carboxylation ofhydroquinone .[ 6]
C6 H4 (OH)2 + CO2 → C6 H3 (CO2 H)(OH)2 This conversion is an example of aKolbe–Schmitt reaction .
Alternatively the compound can be synthesized fromsalicylic acid viaElbs persulfate oxidation .[ 7] [ 8]
In the presence of the enzymegentisate 1,2-dioxygenase , gentisic acid reacts withoxygen to givemaleylpyruvate :
2,5-dihydroxybenzoate + O2 ⇌ {\displaystyle \rightleftharpoons } As ahydroquinone , gentisic acid is readily oxidised and is used as anantioxidant excipient in somepharmaceutical preparations.
In the laboratory, it is used as a sample matrix inmatrix-assisted laser desorption/ionization (MALDI)mass spectrometry ,[ 9] [ 10]
^ 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 PMC 6253884 ^ 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 ISBN 978-0471832539 ^ 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 . ^ 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 . ^ 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 .
