Sn2/Sn1 E2/E1 Rxn Chart

Question 1

steps Sn2/E2

Answer 1

1 step, rate-determining

Question 2

steps Sn1/E1

Answer 2

2 steps, 1st is rate-determining (carbocat forms)

Question 3

big obstacle Sn2/E2

Answer 3

Sn2: sterics blocking Nu

E2: anti-peri planar, base doesn’t join substrate so sterics not a problem

Question 4

big obstacle Sn1/E1

Answer 4

stabilizing carbocation for both

Question 5

stereochemistry Sn2/E2

Answer 5

Sn2: inversion of configuration R –> S

E2: cis OR trans dependent on anti-peri planar t.s.

Question 6

stereochemistry Sn1/E1

Answer 6

Sn1: racemization

E1: both cis AND trans isomers

Question 7

regiochemistry E2

Answer 7

possible products from deprotonation of any B carbon

major prod w/ bulky base: less substituted

major prod w/o bulky base: more substituted

Question 8

regiochemistry E1

Answer 8

possible products from deprotonation of any B carbon

major product: more substituted alkene

e- donating substituents stabilize alkenes

Question 9

Nu quality Sn2/E2

Answer 9

Sn2 & E2 need a good Nu/strong B

if bulky Nu/B, facors E2 vs. Sn2

Question 10

Nu quality Sn1/E1

Answer 10

any Nu/B will work

Question 11

solvent for Sn2/E2

Answer 11

polar aprotic for both

Sn2: protic, H-bonding blocks Nu

E2: protic would protonate the base

Question 12

solvent for Sn1/E1

Answer 12

polar protic for both

H-bonds stabilize carbocation

Question 13

substrates Sn2/E2

Answer 13

Sn2: methyl > 1 > 2; 3rd degree no rxn (sterics)

E2: 1, 2, or 3 (sterics not an issue)

Question 14

substrates Sn1/E1

Answer 14

3 > 2; methyl and 1 give no Sn1/E1

alkyl groups stabilize carbocation

Question 15

strong bases for E2

Answer 15

N- or O-

Question 16

haloalkane rxns: methyl/1st degree

Answer 16

if poor Nu/weak base: no rxn

good Nu/weak base: Sn2

good Nu/strong base: Sn2 unless bulky, then E2

Question 17

if beta carbon is 4th degree

Answer 17

no rxn for Sn2 (sterics)

Question 18

haloalkane rxns: 2nd degree

Answer 18

if poor Nu/weak base: 95% Sn1, 5% E1

if good Nu/weak base: Sn2

if good Nu/strong base: E2

Question 19

haloalkane rxns: 3rd degree

Answer 19

if poor Nu/weak base: 95% Sn1, 5% E1

if good Nu/weak base: 95% Sn1, 5% Eq

if good Nu/strong base: E2

Question 20

alcohol rxns: methyl, 1st degree

Answer 20

nucleophilic acid: Sn2 (no rxn with Cl-)

Question 21

alcohol rxns: 2nd degree

Answer 21

nonnucleophilic acid + heat: E1

nucleophilic acid: 95% Sn1, 5% E1

Question 22

alcohol rxns: 3rd degree

Answer 22

nonnucleophilic acid + heat: E1

nucleophilic acid: 95% Sn1, 5% E1