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The mirror images of these configurations were then designated the L-family of aldoses. To illustrate using present day knowledge, Fischer projection formulas and names for the D-aldose family (three to six-carbon atoms) are shown below, with the asymmetric carbon atoms (chiral centers) colored red.
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23 sty 2023 · One of their most interesting type of isomer is the mirror-image stereoisomers, a non-superimposable set of two molecules that are mirror image of one another. The existence of these molecules are determined by concept known as chirality .
The effect is due to the chirality of the molecules, and indeed the mirror-image isomer, l-(−)-glucose, is levorotatory (rotates polarized light counterclockwise) by the same amount. The strength of the effect is different for each of the five tautomers.
A left directed hydroxyl group (the mirror image) then represented the L-family. Fischer's initial assignment of the D-configuration had a 50:50 chance of being right, but all his subsequent conclusions concerning the relative configurations of various aldoses were soundly based.
If two sugars are identical except for having one chiral carbon arranged differently (such as images glucose and galactose – Figure 2.150), they are considered epimers of one another. If two sugars are mirror images of each other, they are enantiomers (Figure 2.151).
31 sie 2023 · The confusion about D and L arises because L sugars of a given name (glucose, for example) are mirror images of D sugars of the same name. The figure on the previous page shows the structure of D- and L- glucose.
The “left-handed” and “right-handed” forms of a molecule are called enantiomers (mirror images). Figure 13.7 The enantiomers of glyceraldehyde are the result of the different handedness of the central carbon.
