1. Chapter 7: Alkenes and Alkynes I
CH 7-1 Introduction
Structure of alkenes & alkynes
Nomenclature
Relative stabilities of alkenes
Synthesis of alkenes via E1/E2 eliminations:
E2 with small or bulky base
Stereochemistry in E2 eliminations
Cycloalkene eliminations
Acid catalyzed alcohol dehydration
Rearrangements in SN1/E1 reactions
Alkene Hydrogenation (stereospecific syn addition of H2)
Terminal alkynes as nucleophiles

2. Structure of Alkenes
•“Un-saturated hydrocarbons” – contain C=C which is the key to understanding alkene chemical reactivity, HD = 2
• sp2 hybridization; trigonal planar; sigma and pi bonds
•Each sp2 carbon has 3 sigma bonds & 1 pi bond. No C=C bond rotation due to the pi bond. s
cis-2-butene
p-orbitals “overlap”
• Alkenes have Constitutional and Geometric isomers (cis-trans). How many isomers exist for the formula: C4H8

3. Structure of Alkynes
•“Un-saturated hydrocarbons” – contain C-C triple bond.
• Linear geometry; sp hybridization; sigma and pi bonds
• Alkynes have Constitutional isomers (no geometric). How many isomers exist for the formula:
C4H6 (Hint: nine isomers: 3 alkyne, 2 alkene, 4 ring)