Question

What is hyperconjugation?

Answer 1

Hyperconjugation is an extended delocalization of electron density from a `sigma` bond into an adjacent, non-full `p` nonbonding or `pi` orbital that stabilizes the resultant compound.

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A common instance of this occurs in organic chemistry on carbocations.

Adjacent alkyl groups contain `"C"-"H"` `sigma` bonds that will interact with the central empty `p` nonbonding orbital in the carbocation to stabilize the electropositive carbon by providing negative charge density:

Thus, the more alkyl groups around the carbocation (e.g. the more substituted the carbocation), the more stable it is, i.e.

`3^@ > 2^@ > 1^@ > "methyl"` `"carbocation"`,

the tertiary carbocation is more stable than the secondary, which is more stable than the primary, which is more stable than the methyl carbocation.