Chemistry - Halogen Derivative Question with Solution | TestHub

Explanation Question: Question is asking about the most reactive substrate towards ${\mathrm{S}}_{\mathrm{N}}2$ reaction.

Concept: This question is based on mechanism of ${\mathrm{S}}_{\mathrm{N}}2$.

Solution:

Rate of ${\mathrm{S}}_{\mathrm{N}}2\propto$ Electrophilic nature of $\alpha$-carbon atom of $\mathrm{R}-\mathrm{X}$

$$\begin{array}{rlr}& \propto \frac{1}{\text{ Steric hinderance }}& \propto \text{ stability of transition state }\end{array}$$

-I and -M groups increase electrophilicity of $\alpha$-Carbon atom of R-X.

Over all reactivity towards ${\mathrm{S}}_{\mathrm{N}}2$ reaction is :