Lecture on Axial and Equatorial Cyclohexane Planes
Introduction
- Presenter: Casey from the Montreal Student Network
- Topic: Axial and equatorial cyclohexane planes and how to draw chair conformations
Chair Conformation Basics
- Axial Planes
- Generally less stable, especially with large substituents
- Cause steric hindrance due to proximity with other parts
- Equatorial Planes
- More stable and preferred for larger substituents
- Provide more space, reducing steric hindrance
Importance in Cis and Trans Relationships
- Axial and equatorial positions are crucial for determining cis/trans relationships
- Blue crosses/stripes indicate direction (upward/downward)
- 3 axial, 3 equatorial pointing upward
- Substituent Placement
- Larger groups (e.g., tertiary butyl) should preferably be on the equatorial plane
Problem-Solving Approach
- Objective: Draw the most stable chair conformation
- Key Step: Differentiate axial from equatorial to achieve stability
Example 1: Cis-1-tert-Butyl-3-methylcyclohexane
- Naming: T comes before M due to butyl vs. methyl
- Conformation Drawing
- Identify the most bulky group (tert-butyl)
- Place tert-butyl on the equatorial plane
- 1-3 relationship: Ensure both substituents have the same directional orientation (cis)
- Both substituents on equatorial plane = Maximum stability
Example 2: Cis-1-2 Relationship
- Alternating Directions: Axial to equatorial
- Less Stable Configuration
- Sometimes axial must be used for one substituent
- Follow steps to identify the bulky group, place it on equatorial first
- Adjust the other substituent accordingly to maintain cis relationship
Problem-Solving Steps
- Identify the bulky group (e.g., tert-butyl)
- Place the bulky group on the equatorial plane
- Determine the numerical relationship and direction (cis/trans)
- Adjust other substituents as needed
Conclusion
- Emphasize the importance of identifying and placing the bulky group first
- Following these steps ensures efficient and accurate problem solving
- Suggestions for note-taking: Always note the bulky group placement rule
Additional Resources
- Contact Casey for questions via Twitter (handle in video description)
These notes summarize the key points from the lecture on axial and equatorial cyclohexane planes, focusing on chair conformation and problem-solving strategies.