Organic Chemistry/Introduction to reactions/Review of nucleophilic substitution

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Mechanism shared by SN1 and SN2

R-X (electrophile) + Nu- (nucleophile) -> Nu-R (product) + X- (leaving group)

Remeber, SN1 and SN2 are the same reaction just undergoing a different mechanism.


SN1 quick sheet

  • rate-determining step is unimolecular
  • has carbocation intermediate
  • favored by tertiary carbons that can support carbocation
  • works better in a polar protic solvent (solvation effect)
  • tertiary >> secondary electrophile


SN2 quick sheet

  • rate-determining step is bimolecular
  • no carbocation intermediate
  • nucleophile assists leaving group
  • works better in a polar aprotic solvent
  • methyl > primary >> secondary elecrophile
  • steric effects important, favoring small nucleophiles