Chapter 5: 5.9 Selectivity in Elimination Reactions Flashcards
What forms of selectivity can elimination reactions display?
- Regioselectivity
- Stereoselectivity
Define:
Regioselectivity
Preferential elimination at one site over another
Define:
Stereoselectivity
Preferential formation of one stereoisomer over another
What do E2 reactions require?
An anti-periplanar geometry of the proton and leaving group
In E2 Reactions:
What happens when a non-bulky base is used?
The Zaitsev product is formed
What is the Zaitsev product?
It has the most substituted alkene
* The trans product is favoured, due to steric hinderance
In E2 Reactions:
What happens when a bulky base is used?
(Give an example of a bulky base)
The Hofmann product will be formed
* Bulky base: KOtBu
What is the Hofmann product?
The least substituted alkene
What hydrogen will be removed in E2 Reactions?
The one that is anti-periplanar to the leaving group
What is different in selectivity in E1 reactions?
Reactions proceeds through a carbocation intermediate
* Means that we don’t need to worry about anti-periplanar geometry
HOtBu is a…
Neutral bulky base
