Question

Which among $MeX,RC{H}_{2}X,R_{2}CHX\text{and}{R}_{3}CX$ is most reactive towards $S_{N}2$ reaction?

• A. $MeX$
• B. $RC{H}_{2}X$
• C. $R_{3}CX$
• D. $R_{2}CHX$

Answer 1

The correct option is A $MeX$

In $S_{N}2$ reactions, the rate of reaction is mainly dependent on the strength and concentration of the nucleophile. Also, the rate is inversely proportional to the bulkiness of C atom-attached groups. so the reactivity order alkyl halide would be $1^o>2^o>3^o$.
Hence, the correct reactivity order of given alkyl halide would be $MeX>RC{H}_{2}X>R_{2}CHX>R_{3}CX$