MCQEasyJEE 2025Electrophilic Substitution in Benzene

JEE Chemistry 2025 Question with Solution

For the reaction:

Reaction scheme showing aniline on the left converting to bromoaniline on the right, with bromine substituted on the benzene ring and NH2 group retained; product marked as major.

The correct order of set of reagents for the above conversion is :

  • A

    Br2,FeBr3,H2O(Δ),NaOHBr_2, FeBr_3, H_2O(\Delta), NaOH

  • B

    Ac2O,Br2,H2O(Δ),NaOHAc_2O, Br_2, H_2O(\Delta), NaOH

  • C

    H2SO4,Ac2O,Br2,H2O(Δ),NaOHH_2SO_4, Ac_2O, Br_2, H_2O(\Delta), NaOH

  • D

    Ac2O,H2SO4,Br2,NaOHAc_2O, H_2SO_4, Br_2, NaOH

Answer

Correct answer:A

Step-by-step solution

Standard Method

Given: The reaction involves conversion of aniline to ortho-bromoaniline as the major product.

Find: The correct order of reagents for this conversion.

The solution identifies this as a bromination of an amine-containing aromatic ring and states that the correct reagent sequence is:

Br2,FeBr3,H2O(Δ),NaOH\text{Br}_2, \text{FeBr}_3, \text{H}_2\text{O}(\Delta), \text{NaOH}

Here, Br2Br_2 provides bromine, FeBr3FeBr_3 acts as the Lewis acid catalyst for electrophilic aromatic substitution, H2O(Δ)H_2O(\Delta) is used in the subsequent hydrolytic step, and NaOHNaOH neutralizes acidic species formed.

Therefore, the correct option is A.

Step-by-step from the extracted solution

Given: Aniline is converted into 2-bromoaniline.

Find: Which reagent order matches the conversion.

From the extracted solution:

  1. The reaction is analyzed as bromination of aniline.
  2. Br2Br_2 is the brominating reagent.
  3. FeBr3FeBr_3 acts as a Lewis acid catalyst and helps generate the electrophile for aromatic substitution.
  4. H2O(Δ)H_2O(\Delta) is used after substitution as stated in the solution.
  5. NaOHNaOH is used to neutralize acidic intermediates or byproducts.

Hence, the reagent sequence is

Br2,FeBr3,H2O(Δ),NaOH\text{Br}_2, \text{FeBr}_3, \text{H}_2\text{O}(\Delta), \text{NaOH}

This matches option (1).

Therefore, the correct option is A.

Common mistakes

  • Choosing an option containing Ac2OAc_2O first without support from the given solution. This is incorrect because the extracted solution explicitly concludes direct bromination with Br2/FeBr3Br_2/FeBr_3 followed by H2O(Δ)H_2O(\Delta) and NaOHNaOH. Follow the reagent order stated in the worked solution.

  • Ignoring the role of FeBr3FeBr_3 in electrophilic aromatic substitution. This is wrong because the solution identifies FeBr3FeBr_3 as the Lewis acid catalyst needed to activate bromine. Do not treat Br2Br_2 alone as the complete reagent set here.

  • Stopping at bromination and neglecting the later H2O(Δ)H_2O(\Delta) and NaOHNaOH steps. This is incorrect because the asked quantity is the order of set of reagents, not only the first reagent. Use the full sequence given in the solution.

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