Hyperconjugation
Hyperconjugation is best described as:
Select the correct option:
Solution
Donation of σ C–H electron density into adjacent empty or antibonding orbital
- Definition: Hyperconjugation is the permanent delocalization of electrons from a C−H σ bond of an alkyl group to an adjacent empty p-orbital (in carbocations) or a π∗ orbital (in alkenes).
- Alias: Also called No-bond resonance (Baker-Nathan effect).
- Physical Requirement: Needs at least one H atom at the α-carbon relative to the double bond or the positively charged center.
- Impact: It increases the stability of the system. More α-hydrogens ⟹ more hyperconjugative structures ⟹ greater stability.
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Hyperconjugation involves orbital overlap between:
Hyperconjugation involves orbital overlap between:
About This Question
- Subject
- chemistry
- Chapter
- basic organic principles
- Topic
- hyperconjugation
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
Donation of σ C–H electron density into adjacent empty or antibonding orbital
- Definition: Hyperconjugation is the permanent delocalization of electrons from a C−H σ bond of an alkyl group to an adjacent empty p-orbital (in carbocations) or a π∗ orbital (in alkenes).
- Alias: Also called No-bond resonance (Baker-Nathan effect).
- Physical Requirement: Needs at least one H atom at the α-carbon relative to the double bond or the positively charged center.
- Impact: It increases the stability of the system. More α-hydrogens ⟹ more hyperconjugative structures ⟹ greater stability.
This medium difficulty chemistry question is from the chapter basic organic principles, covering the topic of hyperconjugation. It appeared in the 2025 exam.
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