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JEE Main · 2021 · 26 Feb 2021 · Shift 1 · Alcohols Phenols and Ethers

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Identify the major products and respectively in the following reactions of phenol :
  1. (A)(see structures)
    Structure A
    A
    Structure B
    B
  2. (B)(see structures)
    Structure A
    A
    Structure B
    B
  3. (C)(see structures)
    Structure A
    A
    Structure B
    B
    ✓ Correct
  4. (D)(see structures)
    Structure A
    A
    Structure B
    B

Answer: (C)

Solution

Bromine in carbon disulphide at K is a non-polar medium at low temperature, so the bromine is barely polarised and only one substitution occurs. The hydroxyl group is strongly activating and directs that substitution mainly to the position para to itself, so A is -bromophenol.
Chloroform with sodium hydroxide generates dichlorocarbene. The phenoxide ion attacks the carbene from the position ortho to the oxygen, the sodium ion of the phenoxide coordinating the carbene and holding it next to that site; the benzal chloride so formed is hydrolysed on acidification to an aldehyde group. B is therefore salicylaldehyde.
A is -bromophenol and B is salicylaldehyde, that is 2-hydroxybenzaldehyde.

JEE Main · 2021 · 26 Feb 2021 · Shift 1 · Single correct option

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