Alkenes:Electrophilic addition and carbocation rearrangement McM 6'12

1
Alkenes Electrophilic addition and carbocation
rearrangement (McM 6.12) Alkenes Hg-mediated
addition of water or alcohols (McM 7.4,
18.4) Alkynes Hg-mediated addition of water
(McM 8.5) Alkynes Oxidative cleavage (McM
8.7) Alkenes Reactions with carbenes (McM
7.6) Alkenes Addition of radicals (McM 7.10)

2
Cation Rearrangement
1,2 Hydride shift

• Hydride shift
• Alkyl group shift

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Carbenes
McM chapt 7.6, lab ex. 7
Neutral Divalent 6 valence electrons - Highly
reactive Electron deficient /electrophilic
properties
4
electron pair, opposite spin cation / anion
properties
diradical properties Gives triplet signal in esr
spektrum
Triplet normally somewhat more stable than
singlet Singlets more reactive
5
high energy barrier triplet - prod.
prod. from triplet
prod. from singlet
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Polymerization of alkenes (McM 7.10)
Polymers - Synthetic macromolecules

• Radical polymerization
• Cationic polymerization

Conformation of polymer - Properties
linear polymer crystalline solid
Amorphous solid
Both linear and amorph areas
hardness - drawn to fibers
elasticity
7
stereochemistry