Radical Substitution is a type of substitution reaction in which a radical replaces a different atom or group of atoms.
The mechanism for radical substitution is made up of three steps: initiation, propagation, and termination. In this explanation the reaction of methane and bromine will be used, but this mechanism works for many more examples.
This is the step in which free radicals are produced. A radical is a species with an unpaired electron, and they are formed by homolytic fission. Utraviolet radiation has just the right amount of energy to break covalent bonds by homolytic fission. The homolytic fission of bromine is shown…