Hyperconjugation involves overlap of the following orbitals:
Hyperconjugation involves overlap of the following orbitals:
The correct option is C p−p
What is Hyperconjugation ?
The +I effect of alkyl groups when attached to a saturated C atom is in the order: Me3C−>Me2CH−>CH3−. But, the order is reversed when an alkyl group is attached to an unsaturated C atom [e.g., (C=C) or aromatic ring]. In this case,−e−1 -donating effect of alkyl group is explained by hyper-conjugation.
a. Hyper-conjugation is a general stabilizing permanent interaction. It involves delocalization of of the (C−H) bond of an alkyl group directly attached to an atom with an unshared p-orbital. The σ−−e's of the (C−H) bond of the alkyl group enter into partial conjugation with the attached unsaturated system or with the unshared p orbital. For example.
H−H|C|H−CH=CH2⟷H−⊕H C|H=CH−..⊖CH2
(I) (II)↕
H−H|C ⊕H=CH−..⊕CH2⟷⊕H H|C|H=CH−..⊖CH2
(IV) (III)
Conjuction between σ and π orbitals
This type of delocalization leads to a situation where there is no bond between the H and C atoms of the molecule. That is why it is also known as no-bond resonance or Baker-Nathan effect or heterovalent resonance.
Alternatively, the overlap of σ−→e s of α - (C−H) bond with the adjacent π−→e s or vacant p orbitals is called hyper-conjugation.
From the figure, you can see that it is a σ−P overlap.
p−p
What is Hyperconjugation ?
The +I effect of alkyl groups when attached to a saturated C atom is in the order: Me3C−>Me2CH−>CH3−. But, the order is reversed when an alkyl group is attached to an unsaturated C atom [e.g., (C=C) or aromatic ring]. In this case,−e−1 -donating effect of alkyl group is explained by hyper-conjugation.
a. Hyper-conjugation is a general stabilizing permanent interaction. It involves delocalization of of the (C−H) bond of an alkyl group directly attached to an atom with an unshared p-orbital. The σ−−e's of the (C−H) bond of the alkyl group enter into partial conjugation with the attached unsaturated system or with the unshared p orbital. For example.
H−H|C|H−CH=CH2⟷H−⊕H C|H=CH−..⊖CH2
(I) (II)↕
H−H|C ⊕H=CH−..⊕CH2⟷⊕H H|C|H=CH−..⊖CH2
(IV) (III)
Conjuction between σ and π orbitals
This type of delocalization leads to a situation where there is no bond between the H and C atoms of the molecule. That is why it is also known as no-bond resonance or Baker-Nathan effect or heterovalent resonance.
Alternatively, the overlap of σ−→e s of α - (C−H) bond with the adjacent π−→e s or vacant p orbitals is called hyper-conjugation.
From the figure, you can see that it is a σ−P overlap.
