A substitution reaction is a type of chemical reaction in which one functional group in a chemical compound is replaced by another functional group. Substitution reactions are of prime importance in organic chemistry and are classified as either electrophilic or nucleophilic depending on the reagent involved.
In nucleophilic substitution reactions, the substituent is electron-rich and provides the electron pair for bonding with the substrate, which is the molecule being transformed. Examples of nucleophilic reagents include halogen anions, ammonia, the hydroxyl group, the alkoxy group, the cyano group, and the hydrosulfide group. In electrophilic substitution reactions, the substituent is deficient in electrons, and the electron pair for bonding with the substrate comes from the substrate itself.
Substitution reactions can be further classified based on the type of atom or group that acts as the substituent. For example, if an alkyl halide undergoes a substitution reaction with a suitable reagent, it can give rise to numerous types of organic compounds.
Understanding the type of substitution reaction involved in a chemical reaction can help predict the product outcome.
