ORGANIC CHEMISTRYC H E M - 2 0 1

HYPERCONJUGATION

Lesson 6Dr. Erum A. HussainAssociate Professor

Department of ChemistryLCWU

Hyperconjugation Effect

The delocalization of σ-electrons or lone pair of electrons

into adjacent π-orbital or p-orbital is called hyperconjugation.

It occurs due to overlapping of σ-bonding orbital or the

orbital containing a lone pair with adjacent π-orbital or p-orbital.

It is also known as "no bond resonance" or "Baker-Nathan

effect".

There must be an α-CH group or a lone pair on atom

adjacent to sp2 hybrid carbon or other atoms like nitrogen,

oxygen.

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NO BOND RESONANCE

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Orbital diagram

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Stabi l i ty order of Carbocat ions

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Stabi l i ty order of a lkyl radica ls

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HYPERCONJUGATION IN ISOPROPYL CATION

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Hyperconjugat ion in Toluene

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Lets do it ! !

Ionization of Bromoethane

Propene cation

Benzyl radical

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