Electrophilic substitution reactions are chemical reactions in which an electrophile displaces a functional group in a compound, which is typically, but not always, aromatic.
Aromatic substitution reactions are characteristic of aromatic compounds and are common ways of introducing functional groups into benzene rings.
Some aliphatic compounds can undergo electrophilic substitution as well.
The four possible electrophilic aliphatic substitution reaction mechanisms are SE1, SE2(front), SE2(back) and SEi (Substitution Electrophilic), which are also similar to the nucleophile counterparts SN1 and SN2.
In the SE1 course of action the substrate first ionizes into a carbanion and a positively charged organic residue.