Ch 9

Question 1

Sn1

Answer 1

• 1st Order (2 Step)
• Weak Base (and/or poor Nucleophile)
• 3° > 2° > 1 ° NO Me!
• protic solvents (solvates R+ and X)
• ALWAYS with E1
• Attack either side -> Enantiomers

Question 2

E1

Answer 2

• 1st Order (2 Step)
• Weak Base (and/or poor Nucleophile)
• 3° > 2° > 1 ° NO Me!
• protic solvents (solvates R+ and X)
• ALWAYS with E1
• More substituted alkene = major

Question 3

Sn2

Answer 3

• 2nd Order (1 Step)
• STRONG base and/or Good Nuc
• Me > 1° > 2 ° (NEVER 3° for Sn2)
• ***polar aprotic
• NO Bulky Base
• Backside attack–> INVERSION

Question 4

E2

Answer 4

• 2nd Order (1 Step)
• STRONG base and/or Good Nuc
• Me > 1° > 2 ° > 3°
• BULKY Base
• ANTI-periplanar (LG anti to β-H)

Question 5

Sn / E Reactions Summary

Answer 5

Question 6

What’s a Good LG?

Answer 6

Weak Base bc readily accomodates e- cloud

Question 7

Can substitutions happen within a molecule?

Answer 7

Yes

Question 8

Difference between Nucleophiles and Bases

Answer 8

Nucleophiles ATTACK Carbons

Bases ATTACK Protons

Question 9

LG Strength

Answer 9

↓ Basicity

with → PT

with ↓ PT

Question 10

↑ Nucleophilicity

Answer 10

1. If same atom type (e.g. X) is attacker, STRONG Base = Good Nuc
2. As Nucs, Anions > Neutral molecule (bc looser e-)
3. ↑ with ← PT (eneg) AND ↓ PT (size/polarizability)
4. Less Bulkiness

Question 11

Grignard Reagent Formation

Answer 11

R-X + Mg ——-Et₂O (anhydrous ether) or THF —> R-Mg-X

Steps: 1) radical anion 2) R-X split into R^. and X^- 3) R^. + ^.Mg⁺ 4) R-Mg⁺ + X^-

Question 12

Radical Halogenation

Answer 12

Trigonal planar

3 > 2 >1 >> Me

ONLY Cl₂ or Br₂

Propagation steps determine ΔH

Initiation: Cl - Cl (split) —— hv or / heat —-> 2 Cl ^.

Propagation:

1. Abstraction of H⁺ —–> H-Cl + R ^.
2. R ^. + Cl₂ —–> Cl ^. + R-Cl