What is a nucleophilic substitution?
Nucleophilic substitution is the reaction of an electron pair donor (the nucleophile) with an electron pair acceptor (the electrophile).
The most general form for the reaction may be given as
Nuc: + R-LG → R-Nuc + LG:
The electron pair (:) from the nucleophile(Nuc) attacks the substrate (R-LG) forming a new bond, while the leaving group (LG) departs with an electron pair.