Exam 2 Stuff

Question 1

Weak nucleophile/bases (3)

Answer 1

H2O, CH3OH, CH3SH

Question 2

Strong nucleophiles (6)

Answer 2

CN-, N3-, SR-, R3P, R3N, R2S

Question 3

Bulky bases (3)

Answer 3

T-BuO , LDA, TBuLi

Question 4

Strong nucs/strong bases (5)

Answer 4

HO-, RO-, H2N-, R3N, BuLi

Question 5

What type of leaving group (LG) does not allow SN2 reactions to occur due to steric hindrance?

Answer 5

3° LG

Steric hindrance prevents the nucleophile from effectively attacking the electrophile.

Question 6

Why is E2 faster than SN2 on 2° leaving groups?

Answer 6

Due to steric hindrance

E2 reactions are less hindered compared to SN2 in this case.

Question 7

On which type of leaving group does SN2 occur much faster unless a bulky base is present?

Answer 7

1° LG

1° LG allows for easier backside attack by the nucleophile.

Question 8

What is the stereochemical outcome of SN2 reactions?

Answer 8

Inversion of stereochemistry

This is a characteristic feature of SN2 mechanisms.

Question 9

What type of hydrogen is required for the E2 mechanism?

Answer 9

Antiperiplanar hydrogen

This orientation is crucial for the elimination process in E2 reactions.

Question 10

What do bulky bases tend to form during elimination reactions?

Answer 10

The least substituted alkene

Bulky bases favor less sterically hindered products.

Question 11

What rule do small bases follow during elimination reactions?

Answer 11

Saytzev’s Rule

This rule states that the more substituted alkene is favored as the product.

Question 12

What type of solvents do SN2 and E2 reactions prefer?

Answer 12

Polar aprotic solvents

These solvents stabilize the transition state and improve reaction rates.

Question 13

What major pathways do temperature decide in organic reactions?

Answer 13

SN1 and E1

Temperature influences whether a reaction will proceed via the SN1 or E1 pathway.

Question 14

Which rule does the E1 reaction follow?

Answer 14

Saytzev’s Rule

Saytzev’s Rule states that the more substituted alkene will be the major product in elimination reactions.

Question 15

What type of carbocation do SN1 and E1 reactions form?

Answer 15

The most stable carbocation

Stability of carbocations is crucial for the favorability of SN1 and E1 reactions.

Question 16

What should be monitored during carbocation formation?

Answer 16

Rearrangements (no more than 2 shifts)

Carbocation rearrangements can lead to more stable intermediates but are limited to two shifts.

Question 17

Can carbocations form with 1° leaving groups?

Answer 17

No

Primary leaving groups are typically not stable enough to form carbocations.

Question 18

What type of solvents do SN1 and E1 reactions prefer?

Answer 18

Polar protic solvents

Polar protic solvents stabilize the carbocation intermediate and the leaving group.

Question 19

What is the stereochemistry of SN1 and E1 reactions?

Answer 19

No stereochemistry

SN1 and E1 reactions result in racemic mixtures due to the planar nature of the carbocation.

Question 20

What type of reaction arrows are used to indicate SN1 and E1 reactions?

Answer 20

Reversible reaction arrows

The reversibility indicates that the reactions can go in both directions under certain conditions.

Question 21

Study this and work it out in your brain

Answer 21