Substitution reaction

Definition

A substitution reaction is a chemical reaction where an atom or group of atoms in a molecule is replaced by another atom or group of atoms. It is common in organic chemistry, especially involving halogenated compounds.

5 Must Know Facts For Your Next Test

1. Substitution reactions can be classified into nucleophilic and electrophilic types based on the nature of the substituting species.
2. In a nucleophilic substitution reaction, a nucleophile replaces a leaving group in the molecule.
3. Electrophilic substitution reactions typically occur with aromatic compounds, where an electrophile replaces a hydrogen atom.
4. The rate of substitution reactions can be influenced by factors such as the nature of the leaving group, solvent, and temperature.
5. Common examples include the S_N1 and S_N2 mechanisms for nucleophilic substitutions.

Review Questions

• What distinguishes nucleophilic substitution from electrophilic substitution?
• How does the nature of the leaving group affect the rate of a substitution reaction?
• Give an example of a common substitution reaction mechanism.

Related terms

Nucleophile: A chemical species that donates an electron pair to form a chemical bond in relation to a reaction.

Leaving Group: An atom or group that can be readily displaced as stable species during a chemical reaction.

S_N2 Mechanism: $$S_N2$$ (bimolecular nucleophilic substitution) involves simultaneous bond formation and bond breaking in one step.