JEE Chemistry 2024 Question with Solution

Given: Two statements about the reaction mechanisms of secondary alkyl halides are to be checked.

Find: Which option correctly identifies the truth value of Statement I and Statement II.

Analysis of Statement I: $S_N2$ reactions occur by a single concerted step in which the nucleophile attacks from the side opposite to the leaving group. A high concentration of a strong nucleophile increases the rate of the $S_N2$ pathway. For a secondary alkyl halide without bulky substituents, steric hindrance is lower, so the $S_N2$ mechanism is favored. Therefore, Statement I is true.

Analysis of Statement II: $S_N1$ reactions proceed through carbocation formation followed by nucleophilic attack. Secondary alkyl halides can undergo $S_N1$ reaction in the presence of polar protic solvents such as ethanol. A large excess of ethanol helps stabilize the carbocation environment and favors the $S_N1$ mechanism. Therefore, Statement II is also true.

The solution concludes that both statements are true, but it also labels the correct option as A. This conflicts with the listed options. Among the given options, the statement "Both Statement I and Statement II are true" corresponds to Option D.

Therefore, the most defensible answer from the given options should be D.

Given:

• Statement I concerns conditions favoring $S_N2$ for a secondary alkyl halide.
• Statement II concerns treatment of a secondary alkyl halide with excess ethanol.

Find: The correct option matching the truth of the two statements.

For $S_N2$, the important factors are strong nucleophile and low steric hindrance. A secondary alkyl halide can follow $S_N2$ if bulky substituents are absent and the nucleophile is strong. Hence Statement I is true.

For $S_N1$, the important factors are carbocation formation and a polar protic medium. Ethanol is a polar protic solvent and weak nucleophile, so with a secondary alkyl halide it can favor $S_N1$. Hence Statement II is true.

Thus both statements are true. The option text matching this conclusion is D. The solution contains an internal mismatch because it prints "The Correct Option is A" while its own explanation supports D.

Therefore, the correct choice according to the solution reasoning is D.