Threose

Threose ^[1]

d-Threose
l-Threose
Names
IUPAC names d-Threose l-Threose [2]
Systematic IUPAC name (2S,3R)-2,3,4-Trihydroxybutanal (d) (2R,3S)-2,3,4-Trihydroxybutanal (l)
Other names Threotetrose
Identifiers
CAS Number	95-43-2 (d) Y 95-44-3 (l) Y
3D model (JSmol)	(d): Interactive image (l): Interactive image
ChEBI	CHEBI:28587  Y
ChemSpider	388736  Y
ECHA InfoCard	100.002.199
PubChem CID	439665  (d)
UNII	4EHO9A06LX  (d) Y MHH79K1BVR  (l) Y
CompTox Dashboard (EPA)	DTXSID101017421
InChI InChI=1S/C4H8O4/c5-1-3(7)4(8)2-6/h1,3-4,6-8H,2H2/t3-,4-/m1/s1 Y Key: YTBSYETUWUMLBZ-QWWZWVQMSA-N Y InChI=1/C4H8O4/c5-1-3(7)4(8)2-6/h1,3-4,6-8H,2H2/t3-,4-/m1/s1 Key: YTBSYETUWUMLBZ-QWWZWVQMBY
SMILES (d):O=C[C@@H](O)[C@H](O)CO (l):OC[C@H](O)[C@@H](O)C=O
Properties
Chemical formula	C4H8O4
Molar mass	120.104 g·mol−1
Appearance	Syrup
Solubility in water	Very soluble
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N  verify  (what is  YN ?) Infobox references

Threose is a four-carbon monosaccharide with molecular formula C₄H₈O₄. It has a terminal aldehyde group, rather than a ketone, in its linear chain and so is considered part of the aldose family of monosaccharides. The threose name can be used to refer to both the d- and l-stereoisomers and more generally to the racemic mixture (d/L-, equal parts D- and L-) as well as to the more generic threose structure (absolute stereochemistry unspecified).

The prefix "threo-" which derives from threose (and "erythro-" from a corresponding diastereomer erythrose) offer a useful way to describe general organic structures with adjacent chiral centers, where "the prefixes... designate the relative configuration of the centers". ^[3] As is depicted in a Fischer projection of d-threose, the adjacent substituents will have a syn orientation in the isomer referred to as "threo", and are anti in the isomer referred to as "erythro". ^{[3] [4]}

Fischer projections depicting the two enantiomers of threose

Although often inconsequential, threose in aqueous solution mainly exists as the hydrate owing to the following equilibrium: ^[5]

HOCH₂CH(OH)CH(OH)CHO + H₂O ⇌ HOCH₂CH(OH)CH(OH)CH(OH)₂

See also

• Threitol
• Threonic acid
• Threose nucleic acid

References

1. Merck Index, 11th Edition, 9317
2. "Carbohydrate Nomenclature".
3. Formulas Using Other Configurational Notations, W. Rausch, accessed 1 March 2011
4. Prof. Rausch helpfully notes that the prefixes "may be applied to racemic compounds, as well as pure enantiomers and meso compounds", and that when depicted in the common "zig-zag" representation, adjacent "substituents may lie on the same side of the carbon chain... [syn] or on opposite sides... [anti]", which is opposite of their depiction in a Fischer projection.
5. Angyal, SJ; Wheen, RG (1980). "The Composition of Reducing Sugars in Aqueous Solution : Glyceraldehyde, Erythrose, Threose". Australian Journal of Chemistry. 33 (5): 1001. doi:10.1071/CH9801001.