Substitution reaction

In a substitution reaction, a functional group in a particular chemical compound is replaced by another group.

In organic chemistry, the electrophilic and nucleophilic substitution reactions are of prime importance. Organic substitution reactions are classified in several main organic reaction types depending on whether the reagent that brings about the substitution is considered an electrophile or a nucleophile, whether a reactive intermediate involved in the reaction is a carbocation, a carbanion or a free radical or whether the substrate is aliphatic or aromatic. Detailed understanding of a reaction type helps to predict the product outcome in a reaction. It also is helpful for optimizing a reaction with regard to variables such as temperature and choice of solvent.

[edit] Nucleophilic substitutions

A nucleophile reacts with an aliphatic substrate in a nucleophilic aliphatic substitution reaction.
When the substrate is an aromatic compound the reaction type is nucleophilic aromatic substitution.
Carboxylic acid derivatives react with nucleophiles in nucleophilic acyl substitution. This kind of reaction can be useful in preparing compounds

Electrophiles are involved in electrophilic substitution reactions and particularly in electrophilic aromatic substitutions.
Electrophilic reactions to other unsaturated compounds than arenes generally lead to electrophilic addition rather than substitution.

Substituted compounds are chemical compounds where one or more hydrogen atoms of a core structure have been replaced with a functional group like alkyl, hydroxy, or halogen.

For example benzene is a simple aromatic ring and substituted benzenes are a heterogeneous group of chemicals with a wide spectrum of uses and properties:

v • d • e Topics in Organic Reactions

Addition reaction - Elimination reaction - Polymerization - Reagents - Rearrangement reaction - Redox reaction - Regioselectivity - Stereoselectivity - Substitution reaction - List of organic reactions