Which one of the following is more reactive towards $\mathrm{S}_{\mathrm{N}} 2$ reaction?
Which one of the following is more reactive towards $\mathrm{S}_{\mathrm{N}} 2$ reaction?
$\left(\mathrm{CH}_3ight)_3 \mathrm{CX}$
$\left(\mathrm{CH}_3ight)_2 \mathrm{CHX}$
$\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{X}$
$\mathrm{CH}_3 \mathrm{X}$
Solution
Bimolecular nucleophilic substitution $\left(\mathrm{S}_{\mathrm{N}} 2ight)$ reaction involves reaction between reactant and nucleophile simultaneously without the formation of carbocation. Less hindered species are more reactive towards $\mathrm{S}_{\mathrm{N}} 2$ reaction. As $\mathrm{CH}_3 X$ is least hindered alkyl halide, it will show more fast reaction towards $\mathrm{S}_{\mathrm{N}} 2$ reaction.