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Alcohols Phenols and Ethers question

2024 · 5 Apr · Shift 1 · Q2
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  5. /2024 · 5 Apr · Shift 1 · Q2

Alcohols Phenols and Ethers question

2024 · 5 Apr · Shift 1 · Q2

JEE MainChemistryAlcohols Phenols and EthersMCQ+4 / −1
Given below are two statement : Statements I : Bromination of phenol in solvent with low polarity such as CHCl3\mathrm{CHCl}_3CHCl3​ or CS2\mathrm{CS}_2CS2​ requires Lewis acid catalyst. Statements II : The Lewis acid catalyst polarises the bromine to generate Br+\mathrm{Br}^{+}Br+. In the light of the above statements, choose the correct answer from the options given below :
  1. A
    Statement I is true but Statement II is false
  2. B
    Both Statement I and Statement II are true
  3. C
    Statement I is false but Statement II is true
  4. D
    Both Statement I and Statement II are false
View written solutionFree

Correct answer: C

  1. Understand Statement I

Phenol is a strongly activating aromatic compound because the −OH-OH−OH group donates electron density to the benzene ring by resonance.

So, phenol undergoes electrophilic bromination very easily.

  • In non-polar solvents like CS2\mathrm{CS_2}CS2​ or CHCl3\mathrm{CHCl_3}CHCl3​, bromination of phenol gives mainly ortho- and para-bromophenol.
  • Because the ring is already strongly activated, Lewis acid catalyst is not required.

Therefore, Statement I is false.


  1. Understand Statement II

A Lewis acid such as FeBr3\mathrm{FeBr_3}FeBr3​ can polarize Br2\mathrm{Br_2}Br2​:

Br2+FeBr3→Br++FeBr4−\mathrm{Br_2 + FeBr_3 \rightarrow Br^+ + FeBr_4^-}Br2​+FeBr3​→Br++FeBr4−​

More precisely, the Lewis acid makes bromine sufficiently electrophilic, often described in electrophilic substitution as generation of Br+\mathrm{Br^+}Br+ (or a bromonium-like electrophile).

Thus, the statement that Lewis acid catalyst polarises bromine to generate Br+\mathrm{Br^+}Br+ is conceptually true.

Therefore, Statement II is true.


  1. Evaluate options
  • A: Statement I true, Statement II false →\rightarrow→ Incorrect
  • B: Both true →\rightarrow→ Incorrect
  • C: Statement I false, Statement II true →\rightarrow→ Correct
  • D: Both false →\rightarrow→ Incorrect

  1. Final Answer

The correct option is:

C\boxed{\text{C}}C​
  1. Comparison with stored correct answer

Stored correct answer = C

Derived answer = C

So, the derived answer agrees with the stored correct answer.

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