{{#if:58.04 g/molC2H2O21.27 g/cm315|! style="background: #F8EABA; text-align: center;" colspan="2" | Properties
CAS number 107-22-2 YesY
PubChem 7860
ChemSpider 7572 YesY
UNII 50NP6JJ975 YesY
KEGG C14448 YesY
ChEBI CHEBI:34779 YesY
Jmol-3D images Image 1
Molecular formula C2H2O2
Molar mass 58.04 g/mol
Density 1.27 g/cm3
Melting point

15 °C, 288 K, 59 °F

Boiling point

51 °C, 324 K, 124 °F

Specific heat capacity, C 1.044 J/k/g
NFPA 704
NFPA 704.svg
Flash point −4 °C, 269 K, 25 °F
285 °C, 558 K, 545 °F
Related compounds
Related aldehydes acetaldehyde
Related compounds glyoxylic acid
glycolic acid
oxalic acid
pyruvic acid
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Glyoxal is an organic compound with the formula OCHCHO. This yellow colored liquid is the smallest dialdehyde (two aldehyde groups). It is typically applied to paper and textile business as crosslinker for starch-based formulations and as a starting material with ureas for wrinkle-resistant chemical treatments.

It can also be applied in the oilfield as an H2S scavenger for treating sour gas.

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 dioxolanes, with the formula [(HO)CH]2O2CHCHO.[1] Dimer and trimer can precipitate, due to lower solubility, from solution at <40 F.

Properties as an H2S scavenger


Glyoxal offers some benefits over traditional triazine chemistry as an H2S scavenger[2].

  • Glyoxal is effective and can be applied in neutral, acidic, and alkaline conditions (pH environment), where triazine is effective and stable only under alkaline conditions.
  • An acidic formulation allows the product to avoid causing carbonate scaling. It can also be formulated with acid stimulation package to scavenge any potential H2S release.
  • Glyoxal when diluted in water (pH below neutral) does not produce an increased quantity of formaldehyde as a by product, where MEA triazine does.


  • Its reaction with H2S is much slower than triazine, especially at lower temperatures[3].

H2S scavenging test results

The following H2S scavenging results was presented by BASF, a glyoxal vendor.

Scavenging results with 50ppm H2S at 50C and pH of 5.0.


  1. Script error
  2. http://www.basf.de/basf2/img/produkte/intermed/produkte/glyoxal/Glyoxal_as_an_H2S_Scavenger_091001.pdf
  3. Kelland, A.M. Production Chemicals for the Oil and Gas Industry