Question

Choose the correct statement from the following option.

• A. $S_{N}2$ reaction follows second order kinetics
• B. No intermediate is involved in $S_{N}2$ mechanism
• C. $S_{N}2$ reactions are one-step reaction
• D. All the above

Answer 1

The correct option is D All the above

$S_{N}2$ reaction occurs in one step through a transition state. There is no formation of intermediate in it. In transition state, carbon is simultaneously bonded to the incoming nucleophile and the outgoing leaving group. The attack of the attacking reagent on the substrate and departure of leaving group occurs simultaneously.
Thus, $S_{N}2$ reaction is occurs in a single step and it is a concerted reaction.
The rate of the reaction depends on the concentration of both the molecules involved. Therefore, $S_{N}2$ is a bimolecular reaction and follows second order kinetics.