Classification of Compounds Lecture

Introduction

• Focus on classifying compounds as:
  • Stereoisomers
  • Anomers
  • Diastereomers
  • Meso compounds
  • Constitutional isomers

Isomer Definitions

• Isomers: Compounds with the same chemical formula but different structures.
• Constitutional Isomers: Differ in connectivity. Example:
  • Alcohol attached to different carbon atoms.
• Stereoisomers: Same connectivity, different spatial arrangement.
  • Example: Bromine atoms attached to the same carbon but oriented differently in space.

Types of Stereoisomers

1. Enantiomers
   • Non-superimposable mirror images.
   • All chiral centers change configuration.
2. Diastereomers
   • Some but not all chiral centers change.
   • Example:
     • Molecules with chiral centers RRR compared to RSR.
   • Cis-trans Isomers: A subtype of diastereomers.
     • Cis isomers: Same side.
     • Trans isomers: Opposite sides.

Meso Compounds

• Possess a plane of symmetry.
• Despite having chiral centers, they are identical due to symmetry.
• Example:
  • Chiral centers reversed but with symmetry, they are meso.

Classification Examples

1. Enantiomers
   • All chiral centers reversed.
   • No plane of symmetry.
2. Meso Compounds
   • Symmetrical with chiral centers.
3. Constitutional Isomers
   • Differently connected atoms.
   • Example: Bromine atoms on different carbons.
4. Identical Molecules
   • No chiral centers, symmetry present.

Conclusion

• Understanding different kinds of isomers:
  • Enantiomers require all chiral centers to change.
  • Diastereomers involve some changes.
  • Meso compounds are symmetrical with changed configurations.
  • Constitutional isomers have different connectivity.
• Examples illustrate various isomer relationships and classifications.