What is Hyperconjugation?
Hyperconjugation is the stabilizing interaction of the σ electrons (usually C-H or C-C) with an adjacent p-orbital (empty or partially filled or a” π” – orbital) .
Hyperconjugation is known as No bond Resonance or σ-bond” π” orbital resonance.
Hyperconjugation plays an important role in the stability of the following:
- Free Radicals
Hyperconjugation Effect in Carbocation:
Rules for Hyperconjugation in Carbocations:
- Positively charged carbon with empty p – orbital
- C-H sigma bond electrons
The C-H sigma electrons are dispersed or shifted towards the empty p- orbital. As a result of the dispersion(delocalization ) of electrons ,the positive charge on carbon get dispersed and a carbocation get stabilized.
Ethyl Carbocation- Example of Hyperconjugation:
In ethyl carbocation, the positively charged carbon has empty p-orbital (due to the electron deficiency ,carbocation is an electrophile).The sigma electrons are delocalizes between C-H and empty p-orbital .As a result of this interaction, the positive charge on carbon get dispersed and stabilized.
More Hyperconjugation = More stability of Carbocation
How you can calculate the stability of carbocation with hyperconjugation :
Calculating the total number of alpha hydrogen to find the stability of carbocation plays a vital role.
More no. of alpha hydrogen = More hyperconjugation = More stable carbocation
Carbon adjacent to the positively charged carbon is α carbon and all the hydrogen attached with this carbon are α hydrogens.
Stability order of carbocation:
More alkyl groups attached to the positively charged carbon = More Hyperconjugation = More stability
Methyl carbocation< Primary carbocation < secondary carbocation < tertiary carbocation
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Classification of Carbocation:
What are free radicals Chemistry Definition ,Examples ,Formation and Properties
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