OChem Ch 3.4-4

Identical connectivity but different orientation in space

• E from non-ideal bond angle
• E needed for orbitals to distort

E^- repulsion in neighboring eclipsed bonds

Steric crowding of 2 groups across a ring

• Strain free

• All axial H become equilateral
• All equilateral H become axial
• Not a rotation-- Draw a different chair

It favors the chair with the most and larges groups equatorial. The equatorial conformation is favored by a ratio of 95:5.

• 1,3-diaxial interactions is a type of transannular strain.
• Groups 1,3 are in the same axial plane and interact sterically with a larger molecule.
• There is also gauche interactions for each axial group.

• Heterolytic Cleavage
• Homolytic Cleavage

Energy required to break a covalent bond via homolytic cleavage

• 1) Stronger bonds form between overlapping orbitals of the same size
• 2) Stronger bonds create less stable radicals
• 3) Stronger bonds are harder to break

• Hyperconjugation
• Resonance

Stabilization through donation of e- density from neighboring aligned sp3 C-C/C-H sigma bonds

• More hyperconjugation=more stable
• Type of induction

• 1) Initiation
• 2) Propagation
• 3) Termination