Outline the free radical halogenation of alkanes to prepare haloalkanes. Include the mechanism and an example.

Free radical halogenation of alkanes to prepare haloalkanes involves three steps: Initiation, Propagation, and Termination.

1. Initiation: This is the first step where the halogen molecule (like Cl2 or Br2) is broken down into two halogen atoms by ultraviolet light or heat. This process is called homolytic fission. The halogen atoms formed are very reactive and are known as free radicals.

   Example: Cl2 -> 2Cl•

2. Propagation: This is the second step where the free radical formed in the initiation step reacts with the alkane to form a new free radical. This new free radical then reacts with another halogen molecule to form the haloalkane and another free radical. This cycle continues.

   Example: CH4 + Cl• -> •CH3 + HCl •CH3 + Cl2 -> CH3Cl + Cl•

3. Termination: This is the final step where two free radicals combine to form a stable molecule, thus ending the chain reaction.

   Example: Cl• + Cl• -> Cl2

In summary, the free radical halogenation of alkanes to prepare haloalkanes involves the breaking down of a halogen molecule into two free radicals (initiation), the reaction of these free radicals with an alkane to form a new free radical and a haloalkane (propagation), and the combination of two free radicals to form a stable molecule (termination).