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NEET CHEMISTRYAlcohols, Phenols and EthersMedium

Question

Which of the following compounds undergoes nucleophilic substitution reaction most easily?

A

pp-Methylchlorobenzene

B

pp-Nitrochlorobenzene

C

mm-Nitrochlorobenzene

D

Chlorobenzene

Step-by-Step Solution

Haloarenes (like chlorobenzene) are generally very unreactive towards nucleophilic substitution reactions due to resonance stabilization and the partial double-bond character of the C-Cl\text{C-Cl} bond. However, their reactivity increases significantly if an electron-withdrawing group (EWG) such as NO2-\text{NO}_2 is present at the ortho or para positions . The NO2-\text{NO}_2 group at the para position withdraws electron density via both strong I-I (inductive) and R-R (resonance) effects, making the halogen-bearing carbon more electrophilic and stabilizing the intermediate carbanion formed during the reaction. In contrast, an NO2-\text{NO}_2 group at the meta position only exerts a I-I effect, which provides less stabilization, and an electron-donating group like CH3-\text{CH}_3 decreases reactivity. Therefore, pp-nitrochlorobenzene undergoes nucleophilic substitution most easily . (Note: Options were reconstructed based on the standard AIPMT 2011 question as they were missing in the raw data).

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Alcohols, Phenols and Ethers. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

CHEMISTRYAlcohols, Phenols and Ethersfollowingcompoundsundergoesnucleophilicsubstitution

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