Which of the following pairs are examples of enantiomers
## Core Concept
Enantiomers are pairs of molecules that are mirror images of each other but are not superimposable, much like how one's left hand is a mirror image of one's right hand but the two hands are not superimposable. This concept is crucial in stereochemistry, especially in pharmacology, where the biological activity of enantiomers can differ significantly. Enantiomers have the same physical and chemical properties but differ in their optical activity.
## Why the Correct Answer is Right
The correct answer, , represents a pair of molecules that are enantiomers. This is because they are non-superimposable mirror images of each other. For a pair of compounds to be enantiomers, they must have the opposite configuration at every chiral center. This means if one compound has an (R) configuration at a particular chiral center, its enantiomer must have an (S) configuration at that same center.
## Why Each Wrong Option is Incorrect
- **Option A:** represents a pair of molecules that are the same, not enantiomers. They have the same configuration at every chiral center, making them identical rather than mirror images.
- **Option B:** shows a pair of molecules that are diastereomers, not enantiomers. Diastereomers are stereoisomers that are not mirror images of each other, indicating they do not have the opposite configuration at every chiral center.
- **Option D:** depicts a meso compound and its mirror image, which are not enantiomers but rather a compound and itself. A meso compound has a superimposable mirror image due to its internal plane of symmetry.
## Clinical Pearl / High-Yield Fact
A key clinical pearl is that many drugs are chiral, and their enantiomers can have different pharmacokinetic and pharmacodynamic properties. For example, thalidomide, which was famously used to treat morning sickness in the 1950s and 1960s, has one enantiomer that is teratogenic while the other has the desired therapeutic effect. This highlights the importance of understanding stereochemistry in drug development and use.
## Correct Answer: .