JEE Main · 2024 · 31 Jan 2024 · Shift 2 · Hydrocarbons

Identify A and B in the following reaction sequence.

(A)(see structures)
A
B
✓ Correct
(B)(see structures)
(C)(see structures)
(D)(see structures)

Answer: (A)

Solution

Phenol reacts with

B r_{2}

C S_{2}

, a non-polar solvent that keeps the bromination controlled, to give 2,4,6-tribromophenol (A) — the strongly activating

- OH

group directs substitution to both ortho positions and the para position.

Treating A with conc.

HN O_{3}

replaces each ring bromine by a nitro group: the ring, already activated at those positions by

- OH

and destabilized at the C–Br bonds by the three electron-withdrawing bromines, undergoes ipso nitro-substitution at each C–Br site, giving 2,4,6-trinitrophenol, i.e., picric acid (B).

JEE Main · 2024 · 31 Jan 2024 · Shift 2 · Single correct option

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