# What is hyperconjugation?

Jul 22, 2017

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.

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

Adjacent alkyl groups contain $\text{C"-"H}$ $\sigma$ 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.

${3}^{\circ} > {2}^{\circ} > {1}^{\circ} > \text{methyl}$ $\text{carbocation}$,

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