SN2, SN1, E1, E2

Question 1

Sn2
LG: _____
Carbon: _____
Nu: _____
Solvent: _____

Answer 1

good
1°
Strong Nu
Polar aprotic

Question 2

Sn1
LG: _____
Carbon: _____
Nu: _____
Solvent: _____

Answer 2

good
3°
Weak Nu
Polar Protic

Question 3

E2
LG: _____
Carbon: _____
Nu: _____
Solvent: _____

Answer 3

good
3°
Strong Base
Polar aprotic

Question 4

E1
LG: _____
Carbon: _____
Nu: _____
Solvent: _____

Answer 4

good
3°
Weak Base
Polar Protic

Question 5

What facilitates a Good Leaving Group?

Answer 5

Stability of the anions that form after they leave.

This stability is influenced by factors like:

Electronegativity: More electronegative atoms can better stabilize a negative charge, making them good leaving groups.
Size: Larger atoms can distribute the negative charge over a larger area, increasing stability and leaving group ability.
Resonance: Anions that can delocalize the negative charge through resonance are more stable and better leaving groups.
Inductive Effects: Electron-withdrawing groups near the leaving group can stabilize the negative charge through inductive effects, improving leaving group ability.

Question 6

Strong nucleophiles are generally characterized by:

Answer 6

High electron density: This can be due to a negative charge or the presence of lone pairs.
Low electronegativity: Less electronegative atoms are more willing to share their electrons.
Polarizability: Larger atoms with more diffuse electron clouds can better stabilize the developing positive charge in the transition state.
Lack of steric hindrance: Bulky groups around the nucleophilic atom can hinder its approach to the electrophile.

Question 7

Strong bases, on the other hand, are characterized by:

Answer 7

High electron density and willingness to donate electrons: Similar to strong nucleophiles.
Strong affinity for protons (H+): This is the key difference. Strong bases readily accept protons, while strong nucleophiles may or may not have a high affinity for protons.

Question 8

Good Leaving Groups are :

Answer 8

Weak Bases
(their C.A. has a low pKa)
- the better it can exist on it’s own, the more able it is to accept the electron pair

Question 9

True or False:
Equilibrium favors the products of Nucleophilic Substitution rxn’s when the Leaving Group is a Weaker Base than the Nucleophile

Answer 9

True

Question 10

Nucleophiles attack …..
Bases attack …..

Answer 10

• Nucleophiles attack other electron deficient atoms, usually a Carbon
• Bases attack Hydrogens (protons)

Question 11

Strong Nucleophile:

Answer 11

• strong base (high pKa)

Question 12

OH-
CH3O-
CH3CH2O-
R-C≡C-
H-

Answer 12

Strong Nucleophile

Question 13

H2O
CH3OH
CH3CH2OH
Cl- , Br- , I-

Answer 13

Weak Nucleophile

Question 14

NH3
F-

Answer 14

Meh Nucleophile

Question 15

______ Effects can cause Nucleophilicity to NOT parallel Basicity

Answer 15

Steric

Question 16

CN-
SH-
SCH3-

Answer 16

Weak Bases but Strong Nucleophiles

Question 17

In Polar Protic Solvents, Nucleophilicity increases __________ a column

Answer 17

down
F- < Cl- < Br- < I-
- I- is a weak base but a strong nucleophile in polar protic solvents
- looking at size
- the smaller ions are well solvated in solvent molecules thus don’t like to let it go & hold it from the rxn, making weaker nucleophiles

Question 18

In Polar Aprotic Solvents, Nucleophilicity increases __________ a column

Answer 18

up
F- > Cl- > Br- > I-
- since aprotic, it doesn’t solvate anions well
- nucleophilicity follows basicity

Question 19

Polar ________ Solvents:
DMSO
DMF
Acetone
Acetonitrile
THF
HMPA

Answer 19

Polar Aprotic Solvents

Question 20

Polar ________ Solvents:
H2O
CH3OH
CH3CH2OH
CH3COOH
(CH3)3COH

Answer 20

Polar Protic Solvents

Question 21

(Higher or Lower) temperatures favor Elimination
(Higher or Lower) temperatures favor Substitution

Answer 21

Higher for Elim.
Lower for Subs.