Stereochemistry is the branch of chemistry that studies the three-dimensional arrangement of atoms in molecules and how this arrangement affects their physical and chemical properties.
Key points about stereochemistry:
- It deals with spatial orientation of atoms rather than just connectivity.
- Molecules that have the same molecular formula and connectivity but different 3D arrangements are called stereoisomers.
- Stereochemistry explains why two compounds with the same formula may behave differently in biological systems, chemical reactions, or physical properties.
Types of stereoisomers:
- Enantiomers – Non-superimposable mirror images (like left and right hands).
- Diastereomers – Stereoisomers that are not mirror images.
- Cis-trans (geometrical isomers) – Arise due to restricted rotation (like in double bonds or cyclic compounds).
Importance:
- Crucial in pharmaceuticals, because often only one stereoisomer of a drug is effective or safe.
- Helps understand reaction mechanisms (stereoselectivity and stereospecificity).
- Explains phenomena like chirality, optical activity, and conformations of molecules.
In short: Stereochemistry is the study of “molecular 3D shapes” and their impact on properties and reactions.