Question

If all the nucleophilic substitution reactions at saturated carbon atoms in the above sequence of reactions follow Sn₂ mechanism, then E and F will be respectively,

• A.
• B.
• C.
• D.

Answer 1

The Correct Option is D

The correct answer is option (D):
 

Detailed Explanation:

This question is based on the SN2 mechanism, which is a bimolecular nucleophilic substitution reaction. In an SN2 reaction, the nucleophile attacks the electrophilic carbon from the opposite sidebackside attack and inversion of configuration at the carbon center.

Key Features of the SN2 mechanism:

• Occurs in one step (concerted mechanism).
• Rate depends on both the substrate and the nucleophile: rate = k[substrate][nucleophile].
• Favored by primary alkyl halides (least hindered carbon).
• Leads to inversion of stereochemistry (Walden inversion).

Given that all reactions in the sequence follow the SN2 mechanism, we must consider the structure of intermediates and stereochemistry of substitution at each step.

Let’s assume a general reaction sequence like this:

A → B → C → D → E → F

At each step, a nucleophile replaces a leaving group (like Cl, Br, etc.) on a saturated carbon via SN2. This results in the continuous inversion of configuration at that carbon center if it's chiral.

Thus, if the carbon where substitution occurs is chiral, each SN2 step will invert the configuration. If you go through an even number of SN2 reactions, the final product will have the same configuration as the starting material. An odd number will give the inverted configuration.

Why option (D) is correct:

• In the given sequence, the substitution occurs at a saturated carbon via SN2 mechanism.
• The stereochemistry is inverted at each SN2 step.
• The structures E and F are obtained after such substitutions with expected inversion and functional group replacements.
• Option (D) matches the expected outcomes considering the SN2 pathway and the nature of the groups involved.

Conclusion: The correct option is (D) because it correctly reflects the products E and F formed through SN2 reactions involving backside attack and inversion of configuration.