Glyceraldehyde

Glyceraldehyde
IUPAC name 2,3-Dihydroxypropanal
Other names Glyceraldehyde Glyceric aldehyde
Identifiers
CAS number	367-47-5 Y
Jmol-3D images	Image 1
SMILES OCC(O)C=O
Properties[1]
Molecular formula	C3H6O3
Molar mass	90.08 g mol−1
Density	1.455 g/cm³
Melting point	145 °C, 418 K, 293 °F
Boiling point	140-150°C at 0.8 mmHg
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Glyceraldehyde 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

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
Skeletal formula
Ball-and-stick model

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

In the d/l system, glyceraldehyde is used as the configurational standard for carbohydrates. Monosaccharides with a conformation 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

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

• Stereoisomerism

References

1. ^ Merck Index, 11th Edition, 4376