Elimination VS substitution
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When can substitution and elimination reactions occur at the same time?
When they occur under the same reaction conditions
How can you ensure you either get just elimination or substitution products?
By using appropriate reaction conditions
Where does the nucleophile attack in each reaction?
Substitution - attack on carbon Elimination - attack on hydrogen
Which reaction would a large nucleophile do and why?
Elimination Attacks the hydrogen which is small and on the outside of the molecule so it is less sterically hindered
Which reaction would a small nucleophile do and why?
Substitution Empty orbital on carbon has a steric hinderance but a small nucleophile can access the carbon
In the energy diagram, are SN2 or E2 products preferred?
E2 The energy is lower in the transition state
What do E1 and SN1 reactions have the same?
transition state Activation energy intermediate carbenium ion
What are SN1 and E1 reactions controlled by?
The choice and size of nucleophile
The more strongly basic the nucleophile…
The more likely elimination will be
Which type of nucleophiles favour elimination?
Large, basic nucleophiles
What reaction will tBuO- take place in?
Elimination
What is the reaction molarity like in an elimination reaction?
2 molecules to 3 molecules
What is the reaction molarity like in a substitution reaction?
2 molecules to 2 molecules
Which reaction is more entropically favourable?
elimination reaction
Which reaction do high temperatures favour? Why?
Elimination Disorder will increase as the temperature increases
When can E1 and SN1 reactions only occur?
If the intermediate carbenium ion is stabilised
Why is steric hinderance usually not important for elimination?
The nucleophile reacts at the hydrogen of the substrate