What sugar is the c-3 epimer of d-xylose?
b. what sugar is the c-5 epimer of d-allose?
c. what sugar is the c-4 epimer of l-gulose?
d. what sugar is the c-4 epimer of d-lyxose?
Those optical isomers that differs from each other in the configuration of a single carbon atom are called as Epimers. In statement we given with 4 diastereomers (having more than one chiral carbon) and are asked to make its epimer by changing the congfiguration at specific carbon. The epimers of each molecule is drawn on right hand side. The points of change are highlighted blue.
