Dissolving Metal Reduction (Na/NH₃): Alkyne → trans Alkene (Anti Addition)

Learn dissolving metal reduction of alkynes (Na/NH3). Radical anion steps, why addition is anti, and how to predict the trans-alkene product.

• Reaction: Alkyne → trans alkene
• What it does: Reduces alkynes to E-alkenes
• Typical reagents: Na (or Li), liquid NH3, alcohol (proton source)
• Key intermediate: Radical anion + vinyl radical
• Driving force: Stepwise e−/H+ additions; anti stereochemistry emerges from intermediate geometry
• Exam type: Stereochemistry
• Exam type: Reagent selection
• Exam type: Predict product