Question

Reactivity of the following on the basis of \( S_\text{N}1 \) mechanism.

• A. IV>III>I>II
• B. II>IV>III>I
• C. III>IV>I>II
• D. IV>III>II>I

Hint:

In \( S_\text{N}1 \) reactions, the stability of the carbocation intermediates determines the reactivity. More stable carbocations lead to faster reactions.

Answer 1

The Correct Option is A

Step 1: \( S_\text{N}1 \) reaction mechanism.
In the \( S_\text{N}1 \) mechanism, the reactivity depends on the stability of the carbocation formed during the reaction. More stable carbocations lead to faster reactions. The order of stability for carbocations generally follows the trend: \[ \text{Tertiary}>\text{Secondary}>\text{Primary}>\text{Methyl} \] Step 2: Analyze the compounds.
- Compound IV has a tertiary carbocation, which is the most stable and thus most reactive. - Compound III has a secondary carbocation, making it next in reactivity. - Compound I has a primary carbocation, so it is less reactive. - Compound II has a methyl carbocation, the least stable and reactive. Step 3: Conclusion.
The reactivity order is: \[ \text{IV}>\text{III}>\text{I}>\text{II} \] Final Answer: \[ \boxed{\text{IV}>\text{III}>\text{I}>\text{II}} \]