Question

Among the following the compounds which can undergo an $S_{N}1$ reaction in an aqueous solution are:

• A. I and IV only
• B. II and IV only
• C. II and III only
• D. II, III and IV only

Answer 1

The correct option is C II and III only

The compound which can form stable carbocation will undergoes $S_{N}1$reaction more easily.
Due to the presence of 3 methyl groups attached to a carbon, compound II will undergoes $S_{N}1$ reaction.
Carbocation formed from compound II and III are stabilized by hyperconjugation and resonance. Hence, they will undergo $S_{N}1$ reaction.
In (I) structure, the carbocation formed at unsaturated carbon atom is highly unstable and in (IV) the carbocation formed at the bridge which is highly unstable.
Hence, option C is correct