SN2 reaction
The SN2 reaction (also known as bimolecular nucleophilic substitution) is a substitution reaction in organic chemistry. It is a type of nucleophilic substitution, where a lone pair from a nucleophile attacks an electron deficient electrophilic center and bonds to it. This expels another group called a "leaving group". So, the incoming group replaces the leaving group in one step. Since two reacting species are involved in the slow, rate-determining step of the reaction, this leads to the name bimolecular nucleophilic substitution, or SN2. Among inorganic chemists, the SN2 reaction is often known as the interchange mechanism.