Gentisic acid

Gentisic acid^[1]
Names
	IUPAC name 2,5-dihydroxybenzoic acid
	Other names DHB; 2,5-dihydroxybenzoic acid; 5-Hydroxysalicylic acid; Gentianic acid; Carboxyhydroquinone; 2,5-Dioxybenzoic Acid; Hydroquinonecarboxylic acid
Identifiers
CAS Number	490-79-9 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:17189 ;
ChEMBL	ChEMBL1461 ;
ChemSpider	3350 ;
ECHA InfoCard	100.007.017
KEGG	C00628 ;
PubChem CID	3469;
UNII	VP36V95O3T ;
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) Key: WXTMDXOMEHJXQO-UHFFFAOYSA-N ; 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
Chemical formula	C7H6O4
Molar mass	154.12 g/mol
Appearance	white to yellow powder
Melting point	200 - 205 C (Sublimes)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) 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.^[2]

Production

Gentisic acid is produced by carboxylation of hydroquinone.^[3]

C₆H₄(OH)₂ + CO₂ → C₆H₃(CO₂H)(OH)₂

This conversion is an example of a Kolbe–Schmitt reaction.

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, ^[4] and has been shown to conveniently detect peptides incorporating the boronic acid moiety by MALDI. ^[5]

References

^ Gentisic acid - Compound Summary, PubChem.
^ Levy, G (1972-09-31). "Salicylate accumulation kinetics in man". New England Journal of Medicine. 287 (9): 430–2. doi:10.1056/NEJM197208312870903. PMID 5044917. {{cite journal}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Phillip M. Hudnall "Hydroquinone" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. 2005 Wiley-VCH, Weinheim. doi:10.1002/14356007.a13_499.
^ 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 Processes. 72 (111): 89–102. Bibcode:1991IJMSI.111...89S. doi:10.1016/0168-1176(91)85050-V.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Crumpton, J. (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. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[1] Gentisic acid - Compound Summary, PubChem.

[2] Levy, G (1972-09-31). "Salicylate accumulation kinetics in man". New England Journal of Medicine. 287 (9): 430–2. doi:10.1056/NEJM197208312870903. PMID 5044917. {{cite journal}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Ullmann-3] Phillip M. Hudnall "Hydroquinone" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. 2005 Wiley-VCH, Weinheim. doi:10.1002/14356007.a13_499.

[4] 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 Processes. 72 (111): 89–102. Bibcode:1991IJMSI.111...89S. doi:10.1016/0168-1176(91)85050-V.{{cite journal}}: CS1 maint: multiple names: authors list (link)

[5] Crumpton, J. (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. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

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