The unpaired electron makes radicals a highly reactive species.
Consequently, radicals undergo three forms of reactions to achieve stability:
first, by combining with another radical and forming a spin‐paired molecule;
second, by reacting with another spin‐paired molecule to generate a new radical and a new spin‐paired molecule;
third, by decomposing in a unimolecular reaction to form a new radical and a spin‐paired molecule.
These three possible reactions lead to six common steps in radical mechanisms: homolysis, addition to a π bond, hydrogen abstraction, halogen abstraction, elimination, and coupling.
These steps can be categorized into the initiation, propagation, and termination stages of a typical radical mechanism.
Generally, radical reactivity is governed by steric hindrance and electronic stabilization, with electron‐donating and withdrawing groups making radicals nucleophilic and electrophilic, respectively.
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired molecule. These three possible reactions result in six different arrow-pushing patterns in radical mechanisms, such as homolysis, addition to a π bond, hydrogen abstraction, halogen abstraction, elimination, and coupling. These six patterns can be categorized into three typical steps, initiation, propagation, and termination, of a radical mechanism. Typically, these radical reactions are governed by two key factors: steric hindrance and electronic stabilization.