Homolytic and Heterolytic cleavage

Homolytic Cleavage: Equal bond breaking forming Free Radicals ($$\text{R}^\bullet$$).

Heterolytic Cleavage: Unequal bond breaking forming Carbocations ($$\text{R}^+$$) and Carbanions ($$\text{R}^-$$).

Intermediates Stability Orders:

Carbocation ($$sp^2$$):

$$\text{Benzyl} > \text{Allyl} > 3^\circ > 2^\circ > 1^\circ > \text{Methyl}$$

Free Radical ($$sp^2$$):

$$\text{Benzyl} > \text{Allyl} > 3^\circ > 2^\circ > 1^\circ > \text{Methyl}$$

Carbanion ($$sp^3$$):

$$\text{Benzyl} > \text{Allyl} > \text{Methyl} > 1^\circ > 2^\circ > 3^\circ$$