Question

Compare the given compounds for their reactivity in $S_{N}1$ reaction.

• A. $III<II<I$
• B. $I<II<III$
• C. $III<I<II$
• D. None of these

Answer 1

The correct option is D None of these

The increasing order for reactivity towards $S_{N}1$ reaction is

$II<III<I$

The carbocation formed from $II$ is secondary carbocation and not resonance stabilized. Hence, it is least stable and least likely to be formed.

The carbocation formed from $III$ is tertiary carbocation and not resonance stabilized. Hence, it is more stable and more likely to be formed.

The carbocation formed from $I$ is secondary carbocation and resonance stabilized. Hence, it is most stable and most likely to be formed.

The greater is the ease of formation of carbocation, greater is the rate for $S_{N}1$ reaction.