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JEE Main Chemistry Haloalkanes and Haloarenes 2026 JEE Main 2026 (21 January Shift 2)

JEE Main Chemistry Question (2026) — Solution

Question

The correct order of the rate of the reaction for the following reaction with respect to nucleophiles is : CH _ 3 Br + Nu ^ CH _ 3 Nu + Br ^

Options

  1. A. PhO ^ - > ^ - OH > CH _ 3 COO ^ - > ClO _ 4 ^ -
  2. B. CH _ 3 COO ^ - > PhO ^ - > ^ - OH > ClO _ 4 ^ -
  3. C. ^ - OH > PhO ^ - > CH _ 3 COO ^ - > ClO _ 4 ^ -
  4. D. ClO _ 4 ^ - > CH _ 3 COO ^ - > ^ - OH > PhO ^ -

Answer

C. ^ - OH > PhO ^ - > CH _ 3 COO ^ - > ClO _ 4 ^ -

Step-by-step solution

For the SN2 reaction CH₃Br + Nu⁻, nucleophilicity in aprotic solvents is determined by basicity and polarizability. ⁻OH (hydroxide) is the strongest nucleophile and base, making it highly reactive. PhO⁻ (phenoxide) is a good nucleophile with reasonable basicity. CH₃COO⁻ (acetate) is weakened by resonance stabilization of its negative charge across the C-O bonds, reducing its nucleophilicity. ClO₄⁻ (perchlorate) is a very weak nucleophile, being the conjugate base of a strong acid (HClO₄). The correct order of nucleophilicity is: ⁻OH > PhO⁻ > CH₃COO⁻ > ClO₄⁻, which matches option (3).

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Related: Chemistry — Haloalkanes and Haloarenes · All PYQ Banks