Question

Given below are two statements: Statement I: CH\(_3\)-O-CH\(_2\)-Cl will undergo \( S_N1 \) reaction though it is a primary halide.
Statement II: {CH_3-C(-CH_3)(-CH_3)-CH_2-Cl}
will not undergo \( S_N2 \) reaction very easily though it is a primary halide. In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Statement I is incorrect but Statement II is correct.
• B. Both Statement I and Statement II are incorrect.
• C. Statement I is correct but Statement II is incorrect.
• D. Both Statement I and Statement II are correct.

Hint:

The \( S_N1 \) mechanism involves the formation of a carbocation and is favored by stable carbocations, while the \( S_N2 \) mechanism involves a backside attack and is hindered by steric crowding.

Answer 1

The Correct Option is D

To determine the correctness of the statements concerning the likelihood of certain chemical reactions involving primary halides, we must analyze the molecular structure and the mechanism involved.

Statement I: CH\(_3\)-O-CH\(_2\)-Cl will undergo \( S_N1 \) reaction though it is a primary halide. The \( S_N1 \) reaction typically involves formation of a carbocation intermediate, which is more stable in tertiary carbons. However, in this case, if the leaving group, Cl\(^-\), departs, the resulting carbocation is stabilized by the adjacent oxygen atom through resonance. Therefore, Statement I is correct because the resonance stabilization provided by the oxygen allows the primary alkyl halide to undergo a \( S_N1 \) reaction.

Statement II: CH_3-C(-CH_3)(-CH_3)-CH_2-Cl will not undergo \( S_N2 \) reaction very easily though it is a primary halide. The \( S_N2 \) mechanism involves a backside attack, which requires unobstructed access to the electrophilic carbon. Here, even though it is a primary halide, the three bulky methyl groups surrounding the reactive center hinder the approach of the nucleophile, thus impeding the \( S_N2 \) reaction. Therefore, Statement II is correct as the steric hindrance prevents the \( S_N2 \) mechanism.

Based on these analyses, the most appropriate answer is that both Statement I and Statement II are correct.