Hard Practice — Mechanism, Stereochemistry & Synthesis

Chain the ideas: decide SN1 vs SN2 from substrate/nucleophile/solvent and predict stereochemistry (inversion vs racemisation); build synthetic routes (Grignard, cyanide, Finkelstein); reason about haloarene inertness.

  • SN2: 1∘^\circ, strong nucleophile, polar aprotic; single step, inversion. SN1: 3∘^\circ, protic; carbocation, racemisation.
  • Leaving group / reactivity: R−I>R−Br>R−ClR{-}I>R{-}Br>R{-}Cl; haloarenes/vinyl halides are unreactive (resonance, sp2sp^2).