Question

For the following compounds, the correct statement(s) with respect to nucleophilic substitution reactions is(are)

• A. $I$ and $III$ follow $S_{N}1$ mechanism
• B. $I$ and $II$ follow $S_{N}2$ mechanism
• C. Compound $IV$ undergoes inversion of configuration
• D. The order of reactivity for $I,III$ and $IV$ is: $IV>I>III$

Answer 1

Answer: (A), (B), (C)

Benzylic and $3^{\circ }$ halides both follow $S_{N}1$ mechanism.
Benzylic and $1^{\circ }$ halides both follow $S_{N}2$ mechanism.
Benzylic $2^{\circ }$ halides can undergo inversion of configuration.
The order of reactivity would be $IV>I>III$ if both $S_{N}1$ and $S_{N}2$ are considered suitably for substrates.