SN2, E2, SN1, and E1 Reactions

This grouping should provide a clear overview of each reaction type for use in flashcards, highlighting the key characteristics and conditions that favor each mechanism.

SN2 (Bimolecular Nucleophilic Substitution) • Substrate: Primary alkyl halides, some secondary alkyl halides • Nucleophile: Strong nucleophiles (e.g., CN-, OH-, RS-) • Solvent: Polar aprotic (e.g., DMF, DMSO, acetone) • Stereochemistry: Inversion of configuration • Kinetics: Second-order (rate depends on both substrate and nucleophile) • Temperature: Generally favored at lower temperatures • Steric effects: Highly sensitive to steric hindrance E2 (Bimolecular Elimination) • Substrate: Primary, secondary, or tertiary alkyl halides • Base: Strong bases (e.g., NaOEt, KOH) • Stereochemistry: Requires anti-periplanar arrangement • Kinetics: Second-order (rate depends on both substrate and base) • Products: Can form Zaitsev (major) or Hofmann (minor) products • Temperature: Often requires heating • Steric effects: Bulky bases favor Hofmann product SN1 (Unimolecular Nucleophilic Substitution) • Substrate: Tertiary alkyl halides, some secondary alkyl halides • Nucleophile: Weak nucleophiles (e.g., H2O, ROH) • Solvent: Polar protic (e.g., H2O, alcohols) • Stereochemistry: Racemization (loss of stereochemistry) • Kinetics: First-order (rate depends only on substrate) • Carbocation stability: Important factor • Rearrangements: Possible with unstable carbocations E1 (Unimolecular Elimination) • Substrate: Tertiary alkyl halides, some secondary alkyl halides • Base: Weak bases or solvent acting as base • Solvent: Polar protic (e.g., H2O, alcohols) • Kinetics: First-order (rate depends only on substrate) • Products: Generally favors Zaitsev product (more substituted alkene) • Temperature: Often requires heating • Carbocation stability: Important factor Common Factors for All Reactions • Leaving group: Better leaving groups increase reaction rate • Allylic/benzylic substrates: Can undergo all four reactions due to resonance stabilization • Concentration: Higher concentrations of nucleophile/base generally favor SN2 or E2 • Temperature: Higher temperatures generally favor elimination over substitution This grouping should provide a clear overview of each reaction type for use in flashcards, highlighting the key characteristics and conditions that favor each mechanism.