When to Choose SN1, SN2, E1, or E2

Flashcards covering the decision matrix for predicting SN1, SN2, E1, and E2 reaction outcomes based on nucleophile/base strength and substrate substitution.

Strong/Strong Nucleophile and Base (Methyl Substrate)

Yields an $S_N2$ reaction.

Strong/Strong Nucleophile and Base ($1^\circ$ Substrate)

Yields an $S_N2$ reaction.

Strong/Strong Nucleophile and Base ($2^\circ$ and $3^\circ$ Substrates)

Yields an $E_2$ reaction.

Strong/Weak Reagent (Strong Nucleophile / Weak Base) with Methyl, $1^\circ$, and $2^\circ$ Substrates

Yields an $S_N2$ reaction across all three substrate types.

Strong/Weak Reagent (Strong Nucleophile / Weak Base) with $3^\circ$ Substrate

Results in no reaction.

Weak/Strong Reagent (Weak Nucleophile / Strong Base) with Methyl Substrate

Results in no reaction.

Weak/Strong Reagent (Weak Nucleophile / Strong Base) with $1^\circ$, $2^\circ$, and $3^\circ$ Substrates

Yields an $E_2$ reaction across all three substrate types.

Weak/Weak Reagent (Weak Nucleophile / Weak Base) with Methyl and $1^\circ$ Substrates

Results in no reaction.

Weak/Weak Reagent (Weak Nucleophile / Weak Base) with $2^\circ$ and $3^\circ$ Substrates

Yields a mixture of $S_N1$ and $E_1$ reactions ($S_N1 / E_1$).

$S_N1 / S_N2 / E_1 / E_2$ Decision Matrix

A reference table used to determine reaction pathways based on nucleophile/base strength (Strong/strong, Strong/weak, weak/strong, weak/weak) and alkyl substrate type (Methyl, $1^\circ$, $2^\circ$, $3^\circ$).