Free Radical and SN and E

Question 1

Alkyl halide alternative term

Answer 1

Haloalkane

Question 2

Name of cleavage for free radical mechanism

Answer 2

Homolytic cleavage

Question 3

How long does the propagation step last?

Answer 3

It can go on forever, until free radical hits free radical - termination.

Question 4

Why is the tertiary radical the most stable?

Answer 4

Inductive Effect and Hyperconjugation.

Question 5

Regioselective

Answer 5

One pathway is more likely to occur than the other.

Question 6

Problems with conventional Allylic Bromination and Solution

Answer 6

Br likes to go to double bond, and requires a lot of heat to do reaction. Allylic Bromination with NBS solves both problems.

Question 7

NBS

Answer 7

N-Bromosuccinimide

Question 8

The allylic radical is more stable than the normal primary radical because

Answer 8

of resonance

Question 9

Resulting product from free radical mechanism (stereochemistry)

Answer 9

Racemic

Question 10

3 steps of SN1

Answer 10

1. Ionization of alkyl halide (rate determining step)
2. Nucleophile Attacks
3. Proton Extraction

Question 11

Solvolysis

Answer 11

Solvent is nucleophile

Question 12

Factors affecting the rate of SN1/SN2

Answer 12

1. Substrate = alkyl halide 2. Nucleophile (no affect on SN1) 3. Solvent 4. Leaving Group

Question 13

Polar Aprotic Solvents favor what reaction? Why?

Answer 13

Favors SN2, will not solvate Nu

Question 14

Strongest Halogen nucleophile for PAS

Answer 14

F (opposite for PPS)

Question 15

Best leaving group, why?

Answer 15

Iodine, most stable anion, weakest base

Question 16

2 steps in elimination reaction

Answer 16

1. Dehydrohalogenation (removal of X & ß Carbon)

2. Formation of a double bond

Question 17

How to increase E1 product?

Answer 17

Increase temperature

Question 18

E2 requirements

Answer 18

ß Hydrogen and Halogen must be anticoplanar (can still be done in eclipse, but needs a lot of energy to beat steric effect).

Question 19

Which ß elimination reaction takes place on a tertiary alkyl halide (substrate)? Why?

Answer 19

E1 - weak base
E2 - Strong base
Reason: Backside size doesn’t come into play like SN1/2

Question 20

1º alkyl halide, strong nu/base, which reaction is favored?

Answer 20

SN2 (1 bond broken) > E2 (2 bonds broken)

Question 21

Hoffmann Product

Answer 21

Least substituted double bond (opposite of Zaitsev’s Rule)

Question 22

When do we get Hoffmann Product?

Answer 22

Bulky Base