Stereoisomers

Definition

Stereoisomers are a type of isomer where molecules have the same molecular formula and connectivity, but differ in the three-dimensional arrangement of their atoms in space. This spatial arrangement affects the chemical and physical properties of the molecules.

5 Must Know Facts For Your Next Test

1. Stereoisomers have the same molecular formula and connectivity but differ in the spatial arrangement of their atoms.
2. The presence of chiral centers is a key factor in determining whether a molecule can exhibit stereoisomerism.
3. Enantiomers are a type of stereoisomers that are non-superimposable mirror images of each other.
4. Diastereomers are stereoisomers that are not mirror images and have different physical and chemical properties.
5. Stereoisomerism can have significant implications for the biological activity and properties of molecules, particularly in the pharmaceutical industry.

Review Questions

• Explain how the presence of chiral centers in a molecule can lead to the formation of stereoisomers.
  • Chiral centers are atoms, usually carbon, that are bonded to four different substituents. This arrangement creates a non-superimposable mirror image, resulting in the formation of stereoisomers. Molecules with chiral centers can have two or more possible spatial arrangements of their atoms, leading to the existence of stereoisomers that have the same molecular formula and connectivity but differ in their three-dimensional structure.
• Distinguish between enantiomers and diastereomers, and provide examples of each type of stereoisomer.
  • Enantiomers are a type of stereoisomer that are non-superimposable mirror images of each other, meaning they have the same molecular formula and connectivity but differ in their spatial arrangement. For example, the two enantiomers of lactic acid, (R)-lactic acid and (S)-lactic acid, are mirror images. Diastereomers, on the other hand, are stereoisomers that are not mirror images and have different physical and chemical properties. An example of diastereomers would be the cis and trans isomers of 1,2-dichlorocyclohexane, which have different melting points and boiling points.
• Discuss the importance of stereoisomerism in the context of the pharmaceutical industry and the development of new drugs.
  • Stereoisomerism is of critical importance in the pharmaceutical industry because the spatial arrangement of atoms in a molecule can significantly impact its biological activity and properties. Enantiomers, for example, can have vastly different effects on the human body, with one enantiomer being the desired therapeutic agent and the other potentially being ineffective or even harmful. Understanding and controlling stereoisomerism is essential for the development of new drugs, as pharmaceutical companies must ensure the correct spatial arrangement of the active ingredient to maximize the desired therapeutic effect and minimize any adverse side effects.

Related terms

Enantiomers: Enantiomers are a type of stereoisomers that are non-superimposable mirror images of each other, meaning they have the same connectivity but differ in their spatial orientation.

Diastereomers: Diastereomers are a type of stereoisomers that are not mirror images of each other and have different physical and chemical properties.

Chiral Center: A chiral center is an atom, usually a carbon atom, that is bonded to four different substituents, giving the molecule a non-superimposable mirror image.