Glyoxal is an organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 with the formula OCHCHO. This yellow colored liquid is the smallest dialdehyde
A dialdehyde is an organic chemical compound with two aldehyde groups. Examples include:* Glyoxal* Malondialdehyde* Succindialdehyde* Glutaraldehyde- Nomenclature :...

 (two aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

 groups). Its tautomer acetylenediol
Acetylenediol, or ethynediol, is a chemical substance with formula HO-C≡C-OH. It is the diol of acetylene. Acetylenediol is unstable in the condensed phase, although its tautomer glyoxal H2H is well known.-Detection:...

 is unstable.


Commercial glyoxal is prepared either by the gas phase oxidation of ethylene glycol
Ethylene glycol
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid...

 in the presence of a silver or copper catalyst or by the liquid phase oxidation of acetaldehyde with nitric acid. Global nameplate capacity is ~220,000 tons, with production rates less, due to over-capacity mostly in Asia. Most production is done via the gas phase oxidation route.

The first commercial glyoxal source was in Lamotte, France, started in 1960 and currently owned by Clariant. The single largest commercial source is BASF in Ludwigshafen, Germany at ~60,000 tons/annum. Only 2 production sites (Geismer, LA and Charlotte, NC) exist in the Americas. Significant capacity has been added recently in China. Commercial bulk glyoxal is made and reported as a 40%-strength solution.

Glyoxal may be synthesized in the laboratory by oxidation of acetaldehyde
Acetaldehyde is an organic chemical compound with the formula CH3CHO or MeCHO. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale industrially. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants as part...

 with selenious acid. The preparation of anhydrous glyoxal entails heating solid glyoxal hydrate(s) with phosphorus pentoxide
Phosphorus pentoxide
Phosphorus pentoxide is a chemical compound with molecular formula P4O10 . This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant.-Structure:...

 and condensing the vapors in a cold trap
Cold trap
In vacuum applications, a cold trap is a device that condenses all vapors except the permanent gases into a liquid or solid. The most common objective is to prevent vapors from a vacuum pump from contaminating the experiment or sample of interest. Cold traps also refer to the application of cooled...

The experimentally determined Henry's law constants of glyoxal is: KH = 4.19 × 105 × exp[(62.2 × 103/R) × (1/T − 1/298)]


Coated paper
Coated paper
Coated paper is paper which has been coated by a compound to impart certain qualities to the paper, including weight, surface gloss, smoothness or reduced ink absorbency. Kaolinite or calcium carbonate are used to coat paper for high quality printing used in packaging industry and in magazines...

 and in the textile finishes use large amounts of glyoxal as a crosslinker for starch
Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...

-based formulations and as a starting material with ureas for wrinkle-resistant chemical treatments. It is used as a solubilizer
Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the used solvent as well as on...

 and cross-link
Cross-links are bonds that link one polymer chain to another. They can be covalent bonds or ionic bonds. "Polymer chains" can refer to synthetic polymers or natural polymers . When the term "cross-linking" is used in the synthetic polymer science field, it usually refers to the use of...

ing agent in polymer chemistry
Polymer chemistry
Polymer chemistry or macromolecular chemistry is a multidisciplinary science that deals with the chemical synthesis and chemical properties of polymers or macromolecules. According to IUPAC recommendations, macromolecules refer to the individual molecular chains and are the domain of chemistry...

  • proteins (leather tanning process)
  • collagen
  • cellulose derivatives (textiles)
  • hydrocolloids
  • starch (paper coatings)

It is a valuable building block in organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

, especially in the synthesis of heterocycles such as imidazole
Imidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is a diazole and is classified as an alkaloid. Imidazole refers to the parent compound, whereas imidazoles are a class of heterocycles with similar ring structure, but varying substituents...

s. A convenient form of the reagent for use in the laboratory is its bis-hemiacetal with ethylene glycol, 1,4-dioxane-2,3-diol. This compound is commercially available.

Speciation in solution

Glyoxal is supplied typically as a 40% aqueous solution. Like other small aldehydes, glyoxal forms hydrates. Furthermore, the hydrates condense to give a series of oligomers, the structures of which remain uncertain. For most applications, the exact nature of the species in solution is inconsequential. At least two hydrates of glyoxal are sold commercially:
  • glyoxal dimer, dihydrate: [(CHO)2]2[H2O]2, 1,4-dioxane-trans-2,3-diol (CAS# 4845-50-5, m.p. 91-95 C)
  • glyoxal trimer, dihydrate: [(CHO)2]3(H2O)2 (CAS# 4405-13-4).

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 >1 M, dimers predominate. These dimers are probably dioxolane
Dioxolane is a heterocyclic acetal with the chemical formula 2O2CH2. It is related to tetrahydrofuran by interchange of one oxygen for a CH2 group. The corresponding saturated 6-membered C4O2 rings are called dioxanes. The isomeric 1,2-dioxolane is an peroxide...

s, with the formula [(HO)CH]2O2CHCHO. Dimer and trimer can precipitate, due to lower solubility, from solution at <40 F.

Other occurrences

Glyoxal is an inflammatory compound formed when cooking oils and fats are heated to high temperatures.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.