All GRE Subject Test: Chemistry Resources
Example Question #1 : Epimers
The given molecules are __________.
None of these
Stereoisomers have different orientations around a single stereocenter. The two molecules are stereoisomers. Specifically, these molecules are epimers, meaning that they differ at only one stereocenter.
Constitutional isomers have the same molecular formula, but different structures. Conformers have different rotations around a single bond. The molecules are clearly not identical.
Example Question #2 : Epimers
Which of the following carbons represents the stereogenic center between the given isomers?
Epimers are isomers that have different configurations at only one carbon atom. This carbon atom is known as the stereogenic center. The given compounds are identical except for the orientation around carbon number 4; thus, carbon 4 is the stereogenic center.