Glyceraldehyde

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Glyceraldehyde
Glyceraldehyde
D-glyceraldehyde
Identifiers
CAS number 56-82-6 YesY
PubChem 751
ChemSpider 731 YesY
ChEBI CHEBI:5445 YesY
ChEMBL CHEMBL173813 YesY
Jmol-3D images Image 1
Image 3
Properties[1]
Molecular formula C3H6O3
Molar mass 90.08 g mol−1
Density 1.455 g/cm3
Melting point 145 °C (293 °F; 418 K)
Boiling point 140 to 150 at 0.8 mmHg
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Glyceraldehyde (glyceral) is a triose monosaccharide with chemical formula C3H6O3. It is the simplest of all common aldoses. It is a sweet, colorless, crystalline solid that is an intermediate compound in carbohydrate metabolism. The word comes from combining glycerine and aldehyde, as glyceraldehyde is merely glycerine with one hydroxymethylene group changed to an aldehyde.

Structure[edit]

Glyceraldehyde has chiral center and therefore exists as two different enantiomers with opposite optical rotation:

  • R from Latin Rectus meaning "right", or
  • S from Latin sinister meaning "left"
d-glyceraldehyde
(R)-glyceraldehyde
(+)-glyceraldehyde
l-glyceraldehyde
(S)-glyceraldehyde
(−)-glyceraldehyde
Fischer projection D-glyceraldehyde L-glyceraldehyde
Skeletal formula D-glyceraldehyde L-glyceraldehyde
Ball-and-stick model D-glyceraldehyde L-glyceraldehyde

While the optical rotation of glyceraldehyde is (+) for R and (−) for S, this is not true for all monosaccharides. The stereochemical rotation can only be determined by the chemical structure, whereas the optical rotation can only be determined empirically (by experiment).

It was by a lucky guess that the molecular d- geometry was assigned to (+)-glyceraldehyde in the late 19th century, as confirmed by X-ray crystallography in 1951.

Nomenclature[edit]

In the d/l system, glyceraldehyde is used as the configurational standard for carbohydrates. Monosaccharides with an absolute configuration identical to (R)-glyceraldehyde at the last stereocentre, for example C5 in glucose, are assigned the stereo-descriptor d-. Those similar to (S)-glyceraldehyde are assigned an l-.

Synthesis and biochemical role[edit]

Glyceraldehyde can be prepared, along with dihydroxyacetone, by the mild oxidation of glycerol, for example with hydrogen peroxide and a ferrous salt as catalyst. Dihydroxyacetone, the simplest ketose, is an isomer of glyceraldehyde. Interconversion of the phosphates of these two compounds, catalyzed by the enzyme triosephosphate isomerase, is an important intermediate step in glycolysis.

See also[edit]

References[edit]

  1. ^ Merck Index, 11th Edition, 4376