Draw Fischer projections for all 2-ketopentoses. Which are d-2-ketopentoses, which are l-2-ketopentoses, and which are enantiomers?
Pentose indicates a five-carbon skeleton. The ketone functional group is present on the second carbon atom. Enantiomers are mirror images of stereoisomers that are not superimposable. There are four stereoisomers present because of the presence of two chiral carbon atoms. The D and L notation are used to distinguish the two enantiomers of the monosaccharides. The monosaccharide is designated with D and L based on the position of the hydrogen atom and hydroxyl group on the second last carbon atom in the Fischer projection. If the hydroxyl group is placed on the left side of the second last carbon atom in the Fischer projection, it is L conformer, and if it is on the right side, then it is D conformer.