Chapter 7
STRUCTURE AND SYNTHESIS OF
ALKENES
Reference: Organic Chemistry", L.G. Wade, Printice Hall, 8th Edition
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7.1 Introduction
Alkenes are hydrocarbons with carbon–carbon double bonds.
Alkenes are sometimes called olefins
7.2 The Orbital Description of the Alkene Double Bond
7.21 The Sigma Bond Framework
Reference: Organic Chemistry", L.G. Wade, Printice Hall, 8th Edition
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7.22 The Pi Bond
7.23 Elements of Unsaturation
Alkenes are said to be unsaturated because they are capable of
adding hydrogen in the presence of a catalyst.
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7.3 Nomenclature of Alkenes
Reference: Organic Chemistry", L.G. Wade, Printice Hall, 8th Edition
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7.4 Nomenclature of Cis-Trans Isomers
7.41 Cis-Trans Nomenclature
7.42 E-Z Nomenclature
To name an alkene by the E-Z system, mentally separate the
double bond into its two ends. Remember how you used the
Cahn–Ingold–Prelog rules
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Reference: Organic Chemistry", L.G. Wade, Printice Hall, 8th Edition
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7.5 Physical Properties of Alkenes
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Reference: Organic Chemistry", L.G. Wade, Printice Hall,
8th
Edition
7.6 Alkene Synthesis by Elimination of Alkyl Halides
Dehydrohalogenation is the elimination of a hydrogen and a halogen
from an alkyl halide to form an alkene
• Dehydrohalogenation by the E2 Mechanism
Example
Reference: Organic Chemistry", L.G. Wade, Printice Hall, 8th Edition
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7.7 Alkene Synthesis by Dehydration of Alcohols
Dehydration of alcohols is a common method for making alkenes.
The word dehydration literally means “removal of water.”
The Mechanism
Reference: Organic Chemistry", L.G. Wade, Printice Hall, 8th Edition
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7.8 Alkene Synthesis by High-Temperature Industrial Methods
7.81 Catalytic Cracking of Alkanes
The least expensive way to make alkenes on a large scale is by the
catalytic cracking of petroleum
7.82 Dehydrogenation of Alkanes
Dehydrogenation is the removal of H2 from a molecule, just the
reverse of hydrogenation. Dehydrogenation of an alkane gives an
alkene
Reference: Organic Chemistry", L.G. Wade, Printice Hall, 8th Edition
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