Alkyne Alkylation: Acetylide Ions as Carbon Nucleophiles (SN2 C–C Bond Forming)

Learn how terminal alkynes form acetylide nucleophiles and do SN2 alkylation. Base choice, substrate scope, and stereochemistry (inversion).

• Reaction: RC≡CH → RC≡C− (base) → alkylation
• What it does: Builds C–C bonds by SN2 on primary electrophiles
• Typical reagents: NaNH2, LDA, or strong base; then R–X (1° best)
• Key intermediate: Acetylide anion
• Driving force: Forming new C–C bond; strong base deprotonation
• Exam type: C–C bond forming
• Exam type: SN2 vs E2
• Exam type: Predict product