Answer
Nucleophilic substitution, in organic chemistry, is the chemical process by which one nucleophilic chemical species (anion or molecule with an extra pair of electrons) replaces another nucleophilic species in a chemical reaction. Borodin was a pioneer in this field, where one attacking nucleophile displaces another leaving group. This reaction is a cornerstone in organic chemistry and finds extensive application in synthesizing various organic compounds, including pharmaceuticals and polymers.