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| Names | |||
|---|---|---|---|
| Preferred IUPAC name Oxaldehyde[1] | |||
| Systematic IUPAC name Ethanedial[1] | |||
| Other names | |||
| Identifiers | |||
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3D model (JSmol) | |||
| ChEBI | |||
| ChemSpider |
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| ECHA InfoCard | 100.003.160 | ||
| KEGG |
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| UNII | |||
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| Properties | |||
| C2H2O2 | |||
| Molar mass | 58.036 g·mol−1 | ||
| Melting point | 15 °C (59 °F; 288 K) | ||
| Boiling point | 51 °C (124 °F; 324 K) | ||
| Thermochemistry | |||
| 1.044 J/(K·g) | |||
| Hazards | |||
| NFPA 704 (fire diamond) | |||
| Flash point | −4 °C (25 °F; 269 K) | ||
| 285 °C (545 °F; 558 K) | |||
| Related compounds | |||
Relatedaldehydes | acetaldehyde glycolaldehyde propanedial methylglyoxal | ||
Related compounds | glyoxylic acid glycolic acid oxalic acid pyruvic acid diacetyl acetylacetone | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Glyoxal is anorganic compound with thechemical formula OCHCHO. It is the smallestdialdehyde (a compound with twoaldehyde groups). It is a crystalline solid, white at low temperatures and yellow near themelting point (15 °C). The liquid is yellow, and the vapor is green.[2]
Pure glyoxal is not commonly encountered because glyoxal is usually handled as a 40% aqueous solution (density near 1.24 g/mL). It forms a series ofhydrates, includingoligomers. For many purposes, these hydrated oligomers behave equivalently to glyoxal. Glyoxal is produced industrially as a precursor to many products.[3]
Glyoxal was first prepared and named by the German-British chemistHeinrich Debus (1824–1915) by reactingethanol withnitric acid.[4][5]
Commercial glyoxal is prepared either by the gas-phaseoxidation ofethylene glycol in the presence of asilver orcoppercatalyst (the Laporte process) or by the liquid-phase oxidation ofacetaldehyde withnitric acid.[3]
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The first commercial glyoxal source was inLamotte, France, started in 1960. The single largest commercial source isBASF inLudwigshafen,Germany, at around 60,000 tons per year. Other production sites exist also in the US and China. Commercial bulk glyoxal is made and reported as a 40% solution in water by weight[3] (approx. 1:5 molar ratio of glyoxal to water).
Glyoxal may be synthesized in the laboratory by oxidation ofacetaldehyde withselenious acid[6] or byozonolysis ofbenzene.[7]
Anhydrous glyoxal is prepared by heating solid glyoxal hydrate(s) withphosphorus pentoxide and condensing the vapors in acold trap.[8]
The experimentally determinedHenry's law constant of glyoxal is:
Advanced glycation end-products (AGEs) are proteins or lipids that becomeglycated as the result of a high-sugar diet.[10] They are a bio-marker implicated in aging and the development, or worsening, of manydegenerative diseases, such asdiabetes,atherosclerosis,chronic kidney disease, andAlzheimer's disease.[11]
Guanine bases inDNA can undergo non-enzymaticglycation by glyoxal to form glyoxal-guanine adducts.[12] These adducts may then produceDNA crosslinks. Glycation of DNA may also lead tomutation, breaks in DNA andcytotoxicity.[13] In humans, glyoxal-glycated nucleotides can be repaired by the protein DJ-1 also known as Park7.[13]
Coated paper andtextile finishes use large amounts of glyoxal as acrosslinker forstarch-based formulations. It condenses withurea to afford 4,5-dihydroxy-2-imidazolidinone, which further reacts withformaldehyde to give the bis(hydroxymethyl) derivativedimethylol ethylene urea, which is used for wrinkle-resistant chemical treatments of clothing, i.e. permanent press.[3]
Glyoxal is used as asolubilizer andcross-linking agent inpolymer chemistry.
Glyoxal is a valuable building block inorganic synthesis, especially in the synthesis ofheterocycles such asimidazoles.[14] A convenient form of the reagent for use in the laboratory is its bis(hemiacetal) withethylene glycol, 1,4-dioxane-2,3-diol. This compound is commercially available.
Glyoxal solutions can also be used as afixative forhistology, that is, a method of preserving cells for examining them under a microscope.
Glyoxal is supplied typically as a 40% aqueous solution.[3] Like other smallaldehydes, glyoxal forms hydrates. Furthermore, the hydrates condense to give a series of oligomers, some of which remain of uncertain structure. For most applications, the exact nature of the species in solution is inconsequential. At least one hydrate of glyoxal is sold commercially, glyoxal trimer dihydrate: [(CHO)2]3(H2O)2 (CAS 4405-13-4).Other glyoxal equivalents are available, such as the ethylene glycol hemiacetal 1,4-dioxane-trans-2,3-diol (CAS 4845-50-5,m.p. 91–95 °C).
It is estimated that, at concentrations less than 1 M, glyoxal exists predominantly as the monomer or hydrates thereof, i.e., OCHCHO, OCHCH(OH)2, or (HO)2CHCH(OH)2. At concentrations above 1 M, dimers predominate. These dimers are probablydioxolanes, with the formula [(HO)CH]2O2CHCHO. Dimer and trimers precipitate as solids from cold solutions.[15]
Glyoxal has been observed as atrace gas in the atmosphere, e.g. as an oxidation product of hydrocarbons.[16]Tropospheric concentrations of 0–200 ppt by volume have been reported, in polluted regions up to 1 ppb by volume.[17]
TheLD50 (oral, rats) is 3.3 g/kg,[3] when that of commonsalt is 3 g/kg.[18]
Man erhitzt nun das Glyoxal-Phosphorpentoxyd-Gemisch mit freier Flamme und beobachtet bald, dass sich unter Schwarzfärbung des Kolbeninhalte ein flüchtiges grünes Gas bildet, welches sich in der gekühlten Vorlage zu schönen Krystallen von gelber Farbe kondensiert. [One heats the mixture of (crude) glyoxal and P4O10 with an open flame and soon observes, upon blackening of the contents, a mobile green gas which condenses in the cooled flask as beautiful yellow crystals.]
