Overview:
Electrophilic
addition to alkenes takes the following general form:
nuc:
= nucleophile
E+ = electrophile
Electrophilic
addition to alkenes starts with the pi electrons attacking
an electrophile, forming a carbocation on the most stable
carbon. A nucleophile then attacks the carbocation to form
the product. There are many different kinds of such addition,
including:
- Hydroxylation
- Hydrogenation
- Halogenation
- Oxidative
Cleavage
- Hydration
- Epoxidation
- Cyclopropanation
- Halohydrin
Formation
Clearly,
there are numerous kinds of products that can be formed as
a result of this mechanism.
Orientation
of Addition: Electrophilic Addition adds to give the Markovnikov
Product, with the nucleophile added to the more highly substituted
carbon. This is because the carbocation intermediate is significantly
stabilized by alkyl substituents.
Example of electophilic addition to alkenes:
First,
formation of the carbocation on the most highly substituted
carbon
Followed by attack of chloride on the carbocation to give
the addition product
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