Ethan's Notes

    SN1 SN2 E1 E2

    #Chemistry
    Video

    Base, NucleophileMethyl Alkyl HalidePrimary Alkyl HalideSecondary Alkyl HalideTertiary Alkyl Halide
    Strong, StrongSN2SN2(E2 Major Zaistev)(SN2 Minor)E2 Zaistev
    Strong, WeakSN2E2E2 (Small -> Zaistev)(Bulky -> Hofmann)E2 (Small -> Zaistev)(Bulky -> Hofmann)
    Weak, StrongSN2SN2(Polar Aprotic Solvent -> SN2)(Polar Protic Solvent -> SN1)SN1
    Weak, WeakSN2Impractical SN2(Low Heat -> SN1)(High Heat -> E1)(Low Heat -> SN1)(High Heat -> E1)

    Strong Base, Strong Nucleophile

    • $\displaystyle \ce{^{-}OH}$
    • $\displaystyle \ce{^{-}OMe}$
    • $\displaystyle \ce{^{-}OEt}$
    • $\displaystyle \ce{^{-}C\equiv CH}$

    Strong Base, Weak Nucleophile

    • Small
      • $\displaystyle \ce{H^{-}}$
    • Bulky
      • $\displaystyle \ce{^{-}O t-Bu}$

    Weak Base, Strong Nucleophile

    • $\displaystyle \ce{^{-}Cl}$
    • $\displaystyle \ce{^{-}SH}$
    • $\displaystyle \ce{^{-}F}$
    • $\displaystyle \ce{^{-}Br}$
    • $\displaystyle \ce{^{-}N_{3}}$
    • $\displaystyle \ce{^{-}CN}$
    • $\displaystyle \ce{NH_{3}}$
    • $\displaystyle \ce{H_{2}S}$

    Weak Base, Weak Nucleophile

    • $\displaystyle \ce{H_{2}O}$
    • $\displaystyle \ce{MeOH}$
    • $\displaystyle \ce{EtOH}$

    Notes

    • Adding heat increases the likelihood of elimination over substitution
      • Based on the Gibb's Free Energy equation, increasing $\displaystyle T$ will result in a more negative $\displaystyle \Delta G$ for reactions that have a higher $\displaystyle \Delta S$, and elimination increases entropy more than substitution since it produces multiple products
    • Using protic solvents increases the likelihood of elimination over substitution, E1 over E2, and SN1 over SN2
      • The protic environment stabilizes the leaving group of E1 or SN1
    • See Zaistev's Rule and Hofmann Product for difference