Glyoxylic acid
Names | |
---|---|
Preferred IUPAC name
Oxoacetic acid[1] | |
Systematic IUPAC name
Oxoethanoic acid | |
Other names | |
Identifiers | |
3D model (
JSmol ) |
|
741891 | |
ChEBI | |
ChEMBL | |
ChemSpider | |
DrugBank | |
ECHA InfoCard
|
100.005.508 |
EC Number |
|
25752 | |
KEGG | |
PubChem CID
|
|
UNII | |
CompTox Dashboard (EPA)
|
|
| |
| |
Properties | |
C2H2O3 | |
Molar mass | 74.035 g·mol−1 |
Density | 1.384 g/mL |
Melting point | 80 °C (176 °F; 353 K)[4] |
Boiling point | 111 °C (232 °F; 384 K) |
Acidity (pKa) | 3.18,[2] 3.32 [3] |
Related compounds | |
Other anions
|
glyoxylate
|
Related carboxylic acids
|
formic acid acetic acid glycolic acid oxalic acid propionic acid pyruvic acid |
Related compounds
|
acetaldehyde glyoxal glycolaldehyde |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
Glyoxylic acid or oxoacetic acid is an organic compound. Together with acetic acid, glycolic acid, and oxalic acid, glyoxylic acid is one of the C2 carboxylic acids. It is a colourless solid that occurs naturally and is useful industrially.
Structure and nomenclature
The structure of glyoxylic acid is shown as having an
In aqueous solution, this monohydrate exists in equilibrium with a hemiacylal dimer form:[7]
In isolation, the aldehyde structure has as a major
The Henry's law constant of glyoxylic acid is KH = 1.09 × 104 × exp[(40.0 × 103/R) × (1/T − 1/298)].[9]
Preparations
The
For the historical record, glyoxylic acid was prepared from oxalic acid electrosynthetically:[10][11] in organic synthesis, lead dioxide cathodes were applied for preparing glyoxylic acid from oxalic acid in a sulfuric acid electrolyte.[12]
Hot
Also, ozonolysis of maleic acid is effective.[7]
Biological role
Glyoxylate is an intermediate of the glyoxylate cycle, which enables organisms, such as bacteria,[13] fungi, and plants [14] to convert fatty acids into carbohydrates. The glyoxylate cycle is also important for induction of plant defense mechanisms in response to fungi.[15] The glyoxylate cycle is initiated through the activity of isocitrate lyase, which converts isocitrate into glyoxylate and succinate. Research is being done to co-opt the pathway for a variety of uses such as the biosynthesis of succinate.[16]
In humans
Glyoxylate is produced via two pathways: through the oxidation of glycolate in peroxisomes or through the catabolism of hydroxyproline in mitochondria.[17] In the peroxisomes, glyoxylate is converted into glycine by AGT1 or into oxalate by glycolate oxidase. In the mitochondria, glyoxylate is converted into glycine by AGT2 or into glycolate by glyoxylate reductase. A small amount of glyoxylate is converted into oxalate by cytoplasmic lactate dehydrogenase.[18]
In plants
In addition to being an intermediate in the glyoxylate cycle, glyoxylate is also an important intermediate in the photorespiration pathway. Photorespiration is a result of the side reaction of RuBisCO with O2 instead of CO2. While at first considered a waste of energy and resources, photorespiration has been shown to be an important method of regenerating carbon and CO2, removing toxic phosphoglycolate, and initiating defense mechanisms.[19][20] In photorespiration, glyoxylate is converted from glycolate through the activity of glycolate oxidase in the peroxisome. It is then converted into glycine through parallel actions by SGAT and GGAT, which is then transported into the mitochondria.[21][20] It has also been reported that the pyruvate dehydrogenase complex may play a role in glycolate and glyoxylate metabolism.[22]
Disease relevance
Diabetes
Glyoxylate is thought to be a potential early marker for
Nephrolithiasis
Glyoxylate is involved in the development of hyperoxaluria, a key cause of nephrolithiasis (commonly known as kidney stones). Glyoxylate is both a substrate and inductor of sulfate anion transporter-1 (sat-1), a gene responsible for oxalate transportation, allowing it to increase sat-1 mRNA expression and as a result oxalate efflux from the cell. The increased oxalate release allows the buildup of calcium oxalate in the urine, and thus the eventual formation of kidney stones.[18]
The disruption of glyoxylate metabolism provides an additional mechanism of hyperoxaluria development. Loss of function mutations in the HOGA1 gene leads to a loss of the 4-hydroxy-2-oxoglutarate aldolase, an enzyme in the hydroxyproline to glyoxylate pathway. The glyoxylate resulting from this pathway is normally stored away to prevent oxidation to oxalate in the cytosol. The disrupted pathway, however, causes a buildup of 4-hydroxy-2-oxoglutarate which can also be transported to the cytosol and converted into glyoxylate through a different aldolase. These glyoxylate molecules can be oxidized into oxalate increasing its concentration and causing hyperoxaluria.[17]
Reactions and uses
Glyoxylic acid is about ten times stronger an acid than acetic acid, with an acid dissociation constant of 4.7 × 10−4 (pKa = 3.32):
- OCHCO2H ⇌ OCHCO−
2 + H+
With concentrated base, glyoxylic acid
- 2 OCHCO2H + H2O → HOCH2CO2H + HO2CCO2H
Glyoxylic acid gives heterocycles upon
Phenol derivatives
In general, glyoxylic acid undergoes an electrophilic aromatic substitution reaction with phenols, a versatile step in the synthesis of several other compounds.
The immediate product with
The sequence of reactions, in which glyoxylic acid reacts with guaiacol the phenolic component followed by oxidation and decarboxylation, provides a route to vanillin as a net formylation process.[7][26][27]
Hopkins Cole reaction
Glyoxylic acid is a component of the Hopkins–Cole reaction, used to check for the presence of tryptophan in proteins.[28]
Environmental chemistry
Glyoxylic acid is one of several ketone- and aldehyde-containing carboxylic acids that together are abundant in
Safety
The compound is not very toxic with an LD50 for rats of 2500 mg/kg.
See also
References
- ^ ISBN 978-0-85404-182-4.
- ^ Dissociation Constants Of Organic Acids and Bases (600 compounds), http://zirchrom.com/organic.htm.
- ^ pKa Data Compiled by R. Williams, "Archived copy" (PDF). Archived from the original (PDF) on 2010-06-02. Retrieved 2010-06-02.
{{cite web}}
: CS1 maint: archived copy as title (link). - ^ Merck Index, 11th Edition, 4394
- .
- .
- ^
- .
- S2CID 129747490.
- .
- ^ Cohen, Julius (1920). Practical Organic Chemistry 2nd Ed (PDF). London: Macmillan and Co. Limited. pp. 102–104.
- ISBN 978-1-84628-668-1.
- PMID 3332993.
- PMID 9377475.
- PMID 23850601.
- PMID 23876414.
- ^ S2CID 11549218.
- ^ PMID 21093948.
- ^ "photorespiration". Archived from the original on 2006-12-11. Retrieved 2017-03-09.
- ^ PMID 22303256.
- PMID 25528301.
- PMID 23916564.
- ^ PMID 25525609.
- PMID 23267348.
- PMID 22763581.
- PMID 32189791.
- ^ Kamlet, Jonas; Mathieson, Olin (1953). Manufacture of vanillin and its homologues U.S. Patent 2,640,083 (PDF). U.S. Patent Office.
- ISBN 978-81-224-1736-4.
- PMID 27192089.