Page 13 Flashcards
Which is more stable: 1-butene or 2-butene?
A: 2-butenes (disubstituted) are more stable than 1-butene (monosubstituted).
Between cis-2-butene and trans-2-butene, which is more stable?
A: Trans-2-butene is more stable than cis-2-butene due to less steric crowding.
Why is trans-2-butene more stable than cis-2-butene?
A: Trans-2-butene has substituents on opposite sides of the double bond, minimizing steric interactions.
Why are disubstituted alkenes more stable than monosubstituted alkenes?
A: Disubstituted alkenes benefit from greater hyperconjugation and inductive electron donation from alkyl groups.
What is the least stable butene isomer shown?
A: 1-butene, because it is monosubstituted with only one alkyl group stabilizing the double bond.
How does steric hindrance affect alkene stability?
A: Increased steric hindrance, as in cis-isomers, reduces stability due to repulsion between substituents.
What role does hyperconjugation play in the stability of 2-butene isomers?
A: Both cis- and trans-2-butene benefit from hyperconjugation, but trans is more stable due to reduced steric interactions.
How does substituent positioning impact the stability of butene isomers?
A: The positioning of substituents (cis vs. trans) influences stability through steric interactions and symmetry.
Why is 1-butene less stable than both cis- and trans-2-butene?
A: 1-butene is monosubstituted, offering less hyperconjugation and fewer inductive effects compared to the disubstituted 2-butenes.
What general trend is observed in alkene stability as substitution increases?
A: Alkene stability increases with greater substitution due to increased hyperconjugation and electron donation from alkyl groups.
