Question

Which of the following alkyl halides will undergo \( S_N1 \) reaction most readily?

• A. \( (\text{CH}_3)_3 \text{C} \, \text{F} \)
• B. \( (\text{CH}_3)_3 \text{C} \, \text{Cl} \)
• C. \( (\text{CH}_3)_3 \text{C} \, \text{Br} \)
• D. \( (\text{CH}_3)_3 \text{C} \, \text{I} \)

Hint:

In \( S_N1 \) reactions, the rate
determining step involves the departure of the leaving group. A good leaving group, such as \( \text{I}^
\), facilitates the reaction. The order of leaving group ability is \( I^
>Br^
>Cl^
>F^
\).

Answer 1

The Correct Option is D

For an \( S_N1 \) reaction to occur efficiently, facile departure of the leaving group and stability of the resultant carbocation are essential. Within the halide series, iodide (\( \text{I}^
\)) exhibits superior leaving group ability, outperforming bromide (\( \text{Br}^
\)), chloride (\( \text{Cl}^
\)), and fluoride (\( \text{F}^
\)). Consequently, alkyl halides containing iodine will react via \( S_N1 \) mechanisms with the greatest ease.Final Answer: The alkyl halide \( (\text{CH}_3)_3 \text{C} \, \text{I} \) is the most susceptible to \( S_N1 \) reaction.