Page 38 Flashcards
What conformation is involved in the E2 reaction of cyclohexanes?
A: Conformation B, which has two axial β-hydrogens labeled H_a and H_b .
How many different directions can the E2 reaction occur in cyclohexanes?
A: Two different directions, based on the elimination of H_a or H_b .
What type of product is formed when H_a is eliminated in the E2 reaction?
A: A disubstituted alkene, which is the minor product.
What type of product is formed when H_b is eliminated in the E2 reaction?
A: A trisubstituted alkene, which is the major product.
Which rule predicts the major product in the E2 reaction of cyclohexanes?
A: Zaitsev’s rule, favoring the more stable, trisubstituted alkene.
Why is the trisubstituted alkene the major product?
A: Because it is more stable due to greater substitution at the double bond.
What geometry is required for the E2 elimination to occur?
A: The anti periplanar geometry between the β-hydrogen and the leaving group.
Why are both H_a and H_b reactive in this conformation?
A: They are both in the axial position, aligning properly for the anti periplanar requirement.
How does substitution affect the stability of the double bond in alkenes?
A: More substituted alkenes are more stable due to hyperconjugation and electron-donating effects.
What are the relative stabilities of the products in this reaction?
A: The trisubstituted alkene (major product) is more stable than the disubstituted alkene (minor product).
