The organic compound that gives following qualitative analysis is:
Test
Inference
(a)
Dil. HCl
Insoluble
(b)
NaOH solution
Soluble
(c)
Br2 /water
Decolourization
(A)(see structure)
(B)(see structure)✓ Correct
(C)(see structure)
(D)(see structure)
Answer: (B)
Solution
The compound stays out of dilute HCl, which rules out a basic amine (an amine would dissolve as its ammonium salt). It dissolves in NaOH, so it is acidic, and it decolourises bromine water, so its ring is strongly activated towards electrophilic attack. Phenol fits every test: it is weakly acidic, insoluble in acid but dissolving in NaOH as sodium phenoxide, and its −OH group activates the ring so well that bromine water is taken up at once to precipitate 2,4,6-tribromophenol.
JEE Main · 2019 · 09 Apr 2019 · Shift 1 · Single correct option