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Glucose has a pKa value of 12.16 at 25 °C (77 °F) in water. [26] With six carbon atoms, it is classed as a hexose, a subcategory of the monosaccharides. d-Glucose is one of the sixteen aldohexose stereoisomers. The d-isomer, d-glucose, also known as dextrose, occurs widely in nature, but the l-isomer, l-glucose, does not.
In general, only one of the two enantiomers occurs naturally (for example, D-glucose) and can be metabolized by animals or fermented by yeasts. The term "hexose" sometimes is assumed to include deoxyhexoses , such as fucose and rhamnose : compounds with general formula C 6 H 12 O 6− y that can be described as derived from hexoses by ...
These prefixes are attached to the systematic name of the molecular graph. So for example, D-glucose is D-gluco-hexose, D-ribose is D-ribo-pentose, and D-psicose is D-ribo-hexulose. Note that, in this nomenclature, mirror-image isomers differ only in the ' D '/' L ' prefix, even though all their hydroxyls are reversed.
For example, there are 16 distinct aldohexose stereoisomers, but the name "glucose" means a specific pair of mirror-image aldohexoses. In the Fischer projection, one of the two glucose isomers has the hydroxyl at left on C3, and at right on C4 and C5; while the other isomer has the reversed pattern.
l-Glucose is an organic compound with formula C 6 H 12 O 6 or O=CH[CH(OH)] 5 H, specifically one of the aldohexose monosaccharides. As the l-isomer of glucose, it is the enantiomer of the more common d-glucose. l-Glucose does not occur naturally in living organisms, but can be synthesized in the laboratory.
A molecule with multiple chiral carbons has two forms at each chiral carbon. Isomerization at one chiral carbon of several yields epimers, which differ from one another in absolute configuration at just one chiral carbon. [2] For example, D-glucose and D-mannose differ in configuration at just one chiral carbon. This class is further broken ...
For example, in living organisms, the open-chain isomer of glucose usually exists only transiently, in small amounts; D-glucose is the usual isomer; and L-glucose is rare. Straight-chain molecules are often not literally straight, in the sense that their bond angles are often not 180°, but the name reflects that they are schematically straight.
For example, replacing two atoms of common hydrogen by deuterium (, or ) on an ethane molecule yields two distinct structural isomers, depending on whether the substitutions are both on the same carbon (1,1-dideuteroethane, ) or one on each carbon (1,2-dideuteroethane, ); as if the substituent was chlorine instead of deuterium.