Introduction
Coulson and Moffitt, in 1947, modified Baeyer’s theory by introducing the concept of non-planar ring structures, particularly for cyclohexane.
Key Concepts of Coulson and Moffitt’s:
Non-Planar Structures:
They proposed that cyclohexane is not planar but rather adopts non-planar structures like the chair and boat conformations, which relieve angle strain.
Bond Angle Deformation:
Coulson and Moffitt introduced the idea that bond angles in larger rings can deviate slightly from the ideal tetrahedral angle without causing significant strain.
Stability Explanation:
Cyclohexane:
Cyclohexane is most stable in the chair conformation, where the bond angles are very close to 109.5°, and there is no angle strain.
The boat conformation, while less stable, also demonstrates that cyclohexane can adopt various non-planar forms to relieve strain.
Larger Rings:
For rings larger than cyclohexane, Coulson and Moffitt's modification explains that they can adopt puckered or twisted conformations, reducing angle strain.