A nucleophilic substitution is a chemical reaction. It is a type of substitution, or replacing, reaction. It happens when one nucleophile replaces another one on an atom. The other group leaves the atom and is called a leaving group.
There are different types of nucleophilic substitution. Which type happens depends on the type of the atoms and molecules involved. The two main categories of nucleophilic substitution are the SN1 reaction and the SN2 reaction.
- J. March, Advanced Organic Chemistry, 4th ed., Wiley, New York, 1992.