The lowest asymmetric carbon atom is considered for assigning the configuration of monosaccharides. In glucose, for example, the comparison is made based on the position of the -OH group on the lowest asymmetric carbon, comparing it to the corresponding position in glyceraldehyde to determine D-configuration.
Which carbon atom is considered for assigning the configuration of monosaccharides, and how is the comparison made with glyceraldehyde?
Share
The configuration of monosaccharides is assigned based on the chiral carbon farthest from the carbonyl group, often called the anomeric carbon. This carbon is typically the first asymmetric carbon in the molecule. For aldoses, such as glucose, it is the first carbon, and for ketoses, such as fructose, it is the carbon next to the carbonyl group. The comparison with glyceraldehyde involves examining the spatial arrangement of substituents around this chiral carbon. If the hydroxyl group on the chiral carbon is on the right side in a Fischer projection, it is designated as ‘D’ (for dextrorotatory), and if on the left, it is ‘L’ (for levorotatory).