Substitution reaction
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In a substitution reaction, a group of a particular 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 a 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 helps optimizing a reaction with regard to variables such as temperature and choice of solvent.
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.
Electrophiles are involved in electrophilic aromatic substitutions. Electrophilic reactions to other unsaturated compounds generally lead to electrophilic addition rather than substitution. A radical substitution reaction involves radicals.zh:取代反应