L17 - Alkene Reactivity Flashcards
1
Q
What is a double bond in terms of e- density?
A
Region of high e- density
- isolated (not conjugated)
= nucleophilic
- weaker than sigma bonds
2
Q
How do alkenes undergo electrophilic addition reactions?
A
- db in C-C attack H
- forms carbocations
- X- ion choses most stable carbocation
(Concept of regioselectivity)
3
Q
Why do X- ions chose the more stable carbocation?
A
- inductive effect
Occurs through sigma bonds (alkyl groups are weakly donating) - hyperconjugation
4
Q
What is the rank order for cabocation stabalisation?
A
Tertiary > secondary > primary
5
Q
What are additional stabilising effects?
A
- allylic carbocations
- benzylic carbocation
