Question:medium

The correct order of the rate of the reaction for the following reaction with respect to nucleophiles is :
\( CH_3Br + Nu^\ominus \rightarrow CH_3Nu + Br^\ominus \)

Show Hint

Stronger base = Better nucleophile (when the attacking atom is the same). Hydroxide is always a very strong nucleophile compared to carboxylates or resonance-stabilized phenoxides.
Updated On: Mar 25, 2026
  • \( CH_3COO^\ominus>PhO^\ominus>^\ominus OH>ClO_4^\ominus \)
  • \( ClO_4^\ominus>CH_3COO^\ominus>^\ominus OH>PhO^\ominus \)
  • \( ^\ominus OH>PhO^\ominus>CH_3COO^\ominus>ClO_4^\ominus \)
  • \( PhO^\ominus>^\ominus OH>CH_3COO^\ominus>ClO_4^\ominus \)
Show Solution

The Correct Option is C

Solution and Explanation

To determine the correct order of nucleophiles in this reaction, we need to consider the reactivity of nucleophiles in a nucleophilic substitution reaction. The given reaction is: 

\(CH_3Br + Nu^\ominus \rightarrow CH_3Nu + Br^\ominus\)

In nucleophilic substitution reactions, the strength of the nucleophile plays a significant role in the reaction rate. A stronger nucleophile will lead to a faster reaction. Here is the reasoning for the given options:

  • \(^\ominus OH\): Hydroxide ion is generally a strong nucleophile due to its high electron density and basicity.
  • \(PhO^\ominus\): Phenoxide ion is a good nucleophile but less effective than hydroxide because of resonance stabilization in phenoxide ion, which makes it somewhat less available to react.
  • \(CH_3COO^\ominus\): Acetate ion is a weaker nucleophile compared to hydroxide and phenoxide because it is stabilized by resonance, further reducing its reactivity as a nucleophile.
  • \(ClO_4^\ominus\): Perchlorate ion is a very poor nucleophile since it is highly stabilized by resonance and the negative charge is delocalized over four oxygen atoms, making it the least reactive in terms of nucleophilicity.

Therefore, the correct order of nucleophiles from strongest to weakest is:

\(^\ominus OH > PhO^\ominus > CH_3COO^\ominus > ClO_4^\ominus\)

This is consistent with the correct answer:

\(^\ominus OH>PhO^\ominus>CH_3COO^\ominus>ClO_4^\ominus\)

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