Definition: What is Electrophilic Substitution?

Electrophilic substitution is a chemical reaction in which a functional group from a compound is substituted with an electrophilic species. There are two main types of electrophilic substitution reactions – electrophilic aromatic substitution and electrophilic aliphatic substitution. In the former, a functional group is added to an aromatic compound like benzene, resulting in a wide variety of substituted aromatic compounds ^[1,2].

Examples of Electrophilic Substitution

An example of an electrophilic aromatic substitution is the bromination of benzene resulting in bromobenzene ^[3]. An example of an electrophilic aliphatic compound is the chlorination of acetone ^[4].

Mechanism of Electrophilic Substitution

Let us look at the above image which shows the electrophilic aromatic substitution mechanism. It is a two-step process – the addition of the electrophile, followed by deprotonation ^[3].