Question

What is the general mechanism of free radical halogenation?

Answer 1

Free radical halogenation involves initiation, propagation, and termination steps.

Explanation:

Consider the free radical chlorination of methane.

Step 1. Initiation

The initiation step involves the homolytic cleavage of a `"Cl-Cl"` bond to form two `"Cl"` atoms.

Step 2. Propagation

• A `"C"` atom removes an `"H"` from methane, producing `"HCl"` and a methyl radical.

• The newly-formed methyl radical abstracts a `"Cl"` from a chlorine molecule, producing chloromethane and re-forming a `"Cl"` atom.

Step 3. Termination

In the termination steps, the radicals combine in all possible combinations.

The termination products are chlorine, chloromethane, and ethane.