Optical isomerism (A-level only) Study Guide

Study Guide: Optical Isomerism

1. Chiral Carbon Atoms

• Definition: A chiral carbon is one that is attached to four different groups.
• Identification: Practice identifying chiral centers in various organic molecules. For example, in 2-butanol, the second carbon is chiral.

2. Drawing Optical Isomers

• Visual Representation: Learn to draw the two enantiomers of a chiral molecule. Use dashed and wedged bonds to indicate three-dimensional structure.
• Example: Draw the enantiomers of lactic acid, showing how they are mirror images of each other.

3. Plane-Polarised Light

• Concept: Understand that plane-polarised light is light that vibrates in one plane.
• Rotation: Explore how each enantiomer rotates this light in opposite directions and the significance of this property in pharmaceuticals.

4. Distinguishing Isomerism Types

• Optical vs. Structural Isomerism: Compare and contrast optical isomerism with structural isomerism. Structural isomers have different connectivity, while optical isomers have the same connectivity but differ in spatial arrangement.

5. Applications

• Biological Importance: Discuss the role of optical isomers in biological systems, such as the difference in activity between D- and L-amino acids.