91Ó°ÊÓ

The reaction which involves free radicals is called a free radical reaction.

The free radical reaction is completed in three-step. The first step of the reaction is an initiation then the second step is propagation and the third step is termination.

Initiation Step:

Radical reactions are initiated by light. The reaction is also initiated by UV light. In the first step$\text{Cl-Cl}$bond break, homolytically and $\text{Cl}$free radical is formed. Also, cyclopentane and hydrogen-free radicals form by breaking the $\text{C-H}$bond of the cyclopentane ring.

Propagation step:

In this step, the radicals which are generated in the initiation step collide with each other and new radicals are generated.

Termination step:

When two free radicals collide with each other then the chain is terminated.

a.

mechanism

Mechanism of Reaction a

b.

mechanism

c.

mechanism

Mechanism of Reaction c