Question

How will alkyl radical stability increase?

Answer 1

Stability of alkyl radical:

• The Hyperconjugation effect explains the relative stability of Carbocations.
• It is the partial orbital overlap between a filled bonding orbital to an adjacent unfilled or half-filled orbital.
• The Carbocation is an electron-deficient species since it has an incomplete octet (empty $2\mathrm{p}$ orbital).
• When the alkyl group is connected with a Carbocation, then there will be $\mathrm{C}-\mathrm{C}$ or $\mathrm{C}-\mathrm{H}$ sigma bonds besides the Carbocation Carbon.
• Therefore, the filled orbitals of sigma bonds are ready to partially overlap with the empty $2\mathrm{p}$ orbital.
• This property allows sharing of the electron density with the Carbocation, which can stabilize the Carbocation.
• The more alkyl groups involved, the stronger will be the hyperconjugation effect.
• The tertiary Carbocation is the most stable one since there is three alkyl group present.
• Methyl Carbocation is the least stable since there is no alkyl group present.