Question

To which of the following four types does this reaction belong $B^{-}+R-A\to B-R+A^{-}$

• A. Unimolecular electrophilic substitution
• B. Bimolecular electrophilic substitution
• C. Unimolecular nucleophilic substitution.
• D. Bimolecular nucleophilic substitution.

Answer 1

The correct option is D Bimolecular nucleophilic substitution.

It is $S_{N}2$ type of reaction. In the $S_{N}2$ reaction, the addition of the nucleophile and the departure of the leaving group occur in a concerted (taking place in a single step) manner, hence the name $S_{N}2$: substitution, nucleophilic, bimolecular.