Mechanism Review - Substrate Substitution, Nucleophiles/Bases, and Outcomes

Primary Substrate

Reactions possible: S_N2 and E2

Secondary Substrate

Reactions possible: S_N1, E1, S_N2, E2

Tertiary Substrate

Reactions possible: S_N1, E1, E2

Weak nucleophiles/weak bases

Associated with S_N1 and E1

Ex: H₂O, ROH, RCOOH

Strong nucleophile/weak bases

Associated with S_N2

Ex: CN^-, N₃^-, Cl^-, Br^-, I^-, RS^-, HS^-, RSH, H₂S, RNH₂, R₃P

Strong nucleophiles/strong bases

Associated with S_N2 and E2

Ex: OH^-, RO^-

Strong bulky bases

Associated with E2

Ex: tert-butoxide, DBN, DBU, LDA

Primary with strong nucleophile/weak base

Mechanism: S_N2

Primary with strong nucleophile/strong base

Mechanisms: S_N2 (major products) and E2

Primary with strong bulky base

Mechanism: E2

Secondary with weak nucleophile/weak base

Mechanisms: S_N1 and E1

Secondary with strong nucleophile/weak base

Mechanism: S_N2

Secondary with strong nucleophile/strong base

Mechanisms: S_N2 and E2 (major products)

Secondary with strong bulky base

Mechanism: E2

Tertiary with weak nucleophile/weak base

Mechanisms: S_N1 and E1

Tertiary with strong nucleophile/weak base

Mechanism: S_N1

Tertiary with strong base

Mechanism: E2