Williamson ether synthesis: R-O-Na+ + R'-X → R-O-R' + NaX (SN2 — use 1° or methyl R'X to avoid E2) Example: C2H5ONa + CH3I → C2H5OCH3 + NaI

Wurtz reaction: 2R-X + 2Na → R-R + 2NaX (coupling, dry ether)

Finkelstein reaction: R-Cl + NaI → R-I + NaCl↓ (in acetone — NaCl precipitates, drives equilibrium)

Swarts reaction: R-Cl + AgF → R-F + AgCl↓ (or SbF3) — prepares alkyl fluorides

Wurtz-Fittig: ArX + RX + 2Na → Ar-R + 2NaX

Gabriel phthalimide synthesis: Potassium phthalimide + RX → N-alkylphthalimide → hydrazinolysis → RNH2 (pure primary amine)