2.4

Question 1

What is the criteria for an E2 reaction? `

Answer 1

• Strong base present

Question 2

What is the criteria for an E1 reaction? `

Answer 2

• No nucleophile (first step the same as SN1: if there’s a nucleophile then substitution will occur: competing reactions).

Question 3

How do you know if something is acting as a base or nucleophile? Relevant to E1 (2 step with carbocation).

Answer 3

• Question will tell you.
• If it acts as a base it will steal a H+, leaving 2 spare electrons that can then reform a double bond (but wait that’s E2) and if its a nuc. it will take the

Question 4

Why does it matter whether it’s acting as a base or a nucleophile for an alkene?

Answer 4

• Base: E2

- Nucleophile: addition

Question 5

Steps of an E2 reaction:

Answer 5

• Base eliminates proton of beta carbon at the same time as alkene double bond starts to form and the X group starts to leave.

Question 6

Tertiary alcohol + sodium methoxide does what? Methoxide can be base or nuc

Answer 6

• Can’t do SN2 (too much steric hindrance) if methoxide nuc, so must be base.
• -> Thus tertiary alcohol + base

Question 7

Tertiary alcohol in presence of non-nucleophilic acid?

Answer 7

E1.
If acid acts as nucleophile reactions will compete because they have the same intermediate carbocation following removal of leaving group.
–> Can then either lose a hydrogen to E1 or gain a new group for SN1

Question 8

Strength of base vs of nucleophile?

Answer 8

Direct relationship.

Question 9

Effects of a bulky base?

Answer 9

More sterically hindered bases are E2 promoters.

THE MORE STERICALLY HINDERED A SUBSTANCE IS, THE MORE LIKELY IT IS TO ELIMINATE, AND THE LESS LIKELY IT IS TO SUBSTITUTE

Question 10

What is the significance of the leaving group stability?

Answer 10

Reaction may not proceed without a stable leaving group.

Question 11

E2 vs SN2

Answer 11

E2 and SN2 are both one step reactions.