Gentisic acid
Encyclopedia
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.
.
This conversion is an example of a Kolbe–Schmitt reaction.
, 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
, and has been shown to conveniently detect peptides incorporating the boronic acid moiety by MALDI.
Dihydroxybenzoic acid
Dihydroxybenzoic acids are a type of phenolic acids.There are six main compounds, having all the same molecular formula C7H6O4. Those are:* 2,3-Dihydroxybenzoic acid * 2,4-Dihydroxybenzoic acid...
. It is a derivative of benzoic acid
Benzoic acid
Benzoic acid , C7H6O2 , is a colorless crystalline solid and the simplest aromatic carboxylic acid. The name derived from gum benzoin, which was for a long time the only source for benzoic acid. Its salts are used as a food preservative and benzoic acid is an important precursor for the synthesis...
and a minor (1%) product of the metabolic break down of aspirin
Aspirin
Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...
, excreted by the kidneys.
Production
Gentisic acid is produced by carboxylation of hydroquinoneHydroquinone
Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, having the chemical formula C6H42. Its chemical structure, shown in the table at right, has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid...
.
- C6H4(OH)2 + CO2 → C6H3(CO2H)(OH)2
This conversion is an example of a Kolbe–Schmitt reaction.
Applications
As a hydroquinoneHydroquinone
Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, having the chemical formula C6H42. Its chemical structure, shown in the table at right, has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid...
, gentisic acid is readily oxidised and is used as an antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
excipient
Excipient
An excipient is generally a pharmacologically inactive substance used as a carrier for the active ingredients of a medication. In many cases, an "active" substance may not be easily administered and absorbed by the human body; in such cases the substance in question may be dissolved into or...
in some pharmaceutical preparations.
In the laboratory, it is used as a sample matrix in matrix-assisted laser desorption/ionization
Matrix-assisted laser desorption/ionization
Matrix-assisted laser desorption/ionization is a soft ionization technique used in mass spectrometry, allowing the analysis of biomolecules and large organic molecules , which tend to be fragile and fragment when ionized by more conventional ionization methods...
(MALDI) mass spectrometry
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...
, and has been shown to conveniently detect peptides incorporating the boronic acid moiety by MALDI.