Unit 10: Alkenes: Structure, Stability & Synthesis

Before memorizing addition reactions, students need a reliable framework for why some alkenes are more stable than others and how synthetic conditions create them selectively.

• Rank alkene stability using substitution pattern, hyperconjugation, and stereochemistry.
• Assign E/Z stereochemistry correctly for disubstituted and trisubstituted alkenes.
• Choose common alkene-forming methods including dehydration, dehydrohalogenation, and partial alkyne reduction.
• Connect alkene stability to the regioselectivity observed in elimination reactions.

Checkpoint Questions

Q: Which is usually more stable: 1-butene or trans-2-butene?

A: trans-2-butene, because the alkene is more substituted and avoids cis steric crowding.

Q: How can you make a trans alkene from an alkyne?

A: Use dissolving-metal reduction such as Na or Li in liquid ammonia.