Ease Into Prep with an OAT^® Question of the Day

The correct answer is A.

The last pair of compounds are non-superimposable mirror images and are recognizable as such because the two compounds have two of the groups interchanged about a chiral center. By definition, they are enantiomers. Note that another switch between any two of the four groups will bring the molecule back to its original configuration.

(B) Distortion. These are not diastereomers. Diastereomers are configurational isomers: they have the same connectivity of atoms, differ in their arrangement in space, and are not non-superimposable mirror images of each other.

(C) Distortion. The relationship between these two molecules is more complex than simple constitutional isomerism

(D) Distortion. Conformational isomerism does not characterize these molecules.

(E) Distortion. There is no chance for tautomerization between these molecules.