Ch.7 reagents

Strong Base/bulky base, Weak Nucleophile

• T-BuOK, t-BuONa, t-BuOLi

• DBN, DBU, LDA

• Potassium neopentoxide (KOCH₂C(CH₃)₃), Lithium 2,6-di-tert-butylphenoxide

E2 reaction for all 1/2/3°

E2 = Bulky → Hoffman product

Strong Base, Strong Nucleophile

• NaOH, NaOH2, NaOEt, NaOMe, KOH, NaNH2, LiNH2, NaH

• O-H, R-O

• If you see NaNH₂ in excess, think E2 with triple bond formation on dihalides

• NaOMe + heat → E2

1° = Sn2 (mjr), E2 (mnr)

2° = E2 (mjr), Sn2 (mnr)

3° = E2 only

E2 = Zaitsev product

• Polar aprotic → Sn2 faster

• Ex. DMSO, DMF, acetone

Weak Base, Strong Nucleophile

• I, Br, Cl, RS, CN, HS, N3, H2S, NaS-R, NaSCH3

• Na-, K-

1° = Sn2 only (fast)

2° = Sn2 only

3° = Sn1 only

Sn1 = carbonation must form first

• Polar aprotic → Sn2 faster

• Ex. DMSO, DMF, acetone

Weak Base, Weak Nucleophile

• H2O, EtOH, MeOH,Ch3OOH, R-OH

1° = NO PRODUCT

2° = Sn1/E1

3° = Sn1/E1

• Heat → E1

• Cold/no heat → Sn1

E1 = Zaitsev product

Sn1 = carbonation must form first

• Polar protic → Sn1 and E1 faster

OH not a goo leaving group → how to get rid of?

1. TsCl, Py → OTs (good LG)

2. use a reagent for Sn2 or E2 reaction

3. Conc. H2SO4 + Heat → E2

   • Zaitsev product