Glyoxal

• Oxalaldehyd
• Ethanedial

Below 15 ° C yellow crystals

Liquid

1.14 g · cm -3

15 ° C.

50 ° C.

293 hPa ( 20 ° C)

Good in water ( 600 g · l-1 at 20 ° C)

1.3826 (20 ° C)

Attention

7070 mg · kg -1 ( LD50, rat, oral)

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Ethanedial (common name: glyoxal ) is one of the chemical compounds of the dialdehydes ( divalent aldehydes) and is usually used as 40% aqueous solution traded.

Occurrence

Glyoxal comes as a trace gas in the atmosphere, as a degradation product of hydrocarbons. The tropospheric concentrations are usually here at 0-200 pptv, ppbv in polluted regions up to 1.

Production and representation

The industrial production carried out by the catalytic gas phase oxidation of ethylene with oxygen on silver or copper catalyst at 300 ° C.

In the laboratory, glyoxal can be prepared by oxidation of acetaldehyde with nitric acid and interception of glyoxal sodium bisulfite adduct represented as.

Properties

Glyoxal on heating forms pungent green vapors condense in the cold to yellow prismatic crystals of melting point 15 ° C. It readily polymerizes to colorless polyglyoxal, again produced from the monomer by heating with phosphorus ( V) oxide. In aqueous solution of glyoxal is present as the dihydrate, which can be isolated. Glyoxal is an aqueous solution containing 40 % and as trimeric, solid hydrate (3 C2H2O2 · 2 H2O; vapor pressure at 26 ° C: 378 hPa ) are commercially available. Under the action of aqueous alkali metal hydroxide solution glyoxal becomes the salt of glycolic acid by intramolecular Cannizzaro reaction. It has a very good solubility in water, a Henry's Law constant of 360,000th

Chemical Properties

The two reactive aldehyde groups of glyoxal enable it to a variety of chemical reactions, from which the condensation reaction is to be given with urea to glycoluril here. Due to the possibility of reaction with the hydroxyl groups of the cellulose glyoxal is also used for textile finishing.

Use

Glyoxal is used as a raw material for syntheses and is also used in textile finishing and as a component in disinfectants. You need it for the production of CL20, one of the strongest known explosives.

In medical research glyoxal is used to generate information about the response of the RAGE receptor oxidative stress in cell cultures.