Question

Explain the substitution reaction

Answer 1

Substitution reaction - A Substitution reaction is a chemical reaction in which an atom or group of atoms in a molecule are replaced or substituted by another atom or group of atoms.

A substitution reaction is also known as a single substitution reaction or replacement reaction.

The general format of Substitution reaction

-$$\begin{gathered} \mathrm{R}-\mathrm{LG}+\left(\mathrm{X}\right)\to \mathrm{R}-\mathrm{X}+\mathrm{LG} \\ \mathrm{R}🡪\mathrm{Alkyl}\mathrm{group},\mathrm{LG}🡪\mathrm{Leaving}\mathrm{group} \\ \mathrm{X}-\mathrm{Attacking}\mathrm{gp}.\mathrm{can}\mathrm{be}\mathrm{Nucleophile}\mathrm{and}\mathrm{Electrophile} \end{gathered}$$

Substitution reactions are of two types.

1. Nucleophilic Substitution reaction$\left(\mathrm{NSR}\right)$
2. Electrophilic Substitution reactions$\left(\mathrm{ESR}\right)$

Nucleophilic Substitution reaction$\left(\mathrm{NSR}\right)$- This type of substitution reaction occurs when an atom or group of atoms in a molecule are replaced or substituted by a Nucleophile.

For Example - $$\begin{gathered} {\mathrm{CH}}_3–\mathrm{Br}+{\mathrm{OH}}^{-}\to {\mathrm{CH}}_3–\mathrm{OH}+{\mathrm{Br}}^{-} \\ \mathrm{Br}-\mathrm{Leaving}\mathrm{gp},{\mathrm{OH}}^{-}-\mathrm{Nucleophile} \end{gathered}$$

Electrophilic Substitution reactions$\left(\mathrm{ESR}\right)$- This type of substitution reaction occurs when an atom or group of atoms in a molecule are replaced or substituted by an Electrophile.

For Example -