Free Radical Substitution

Free Radical Substitution

Definition: a type of substitution reaction in which a radical replaces a different atom or group of atoms

Step 1: Initiation

The Cl-Cl bond is broken via homolytic fission to form 2 free radicals. The energy required for this reaction is provided by Ultraviolet radiation.

Step 2: Propagation

In the first step methane reacts with a chlorine radical. A C-H bond is broken via homolytic fission, to form a methyl free radical and hydrogen chloride.

In the second step, the methyl radical reacts with a chlorine molecule. This forms chloromethane along with another chlorine free radical.

Propagation is a chain reaction. The chlorine free radical generated in the second step can be used in the first step. This continues until a termination step occurs. 

Step 3: Termination

In the termination step, two radical join to form a molecule. The termination step stops all reactions by removing the free radicals.

New Page