Match List-I with List-II.
| List-I | List-II |
| (A) C6H5OH + Br2/H2O → | (I) 2,4,6-Tribromophenol |
| (B) C6H5OH + Br2/CS2 (low temperature) → | (II) o-Nitrophenol and p-nitrophenol |
| (C) C6H5OH + dilute HNO3 (298 K) → | (III) 2,4,6-Trinitrophenol |
| (D) C6H5OH + conc. H2SO4, then conc. HNO3 → | (IV) o-Bromophenol and p-bromophenol |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A-I, B-IV, C-II, D-III
The –OH group activates the benzene ring of phenol and directs the incoming group to the ortho and para positions. How many groups enter depends on the reagent and the conditions.
(A) C6H5OH + Br2/H2O → — This matches (I) 2,4,6-Tribromophenol. With bromine water, all three ortho and para positions are substituted and the product separates as a white precipitate:
\( \displaystyle \ce{C6H5OH + 3Br2} \xrightarrow{\ce{H2O}} \ce{C6H2Br3OH + 3HBr} \)
(B) C6H5OH + Br2/CS2 (low temperature) → — This matches (IV) o-Bromophenol and p-bromophenol. In a solvent of low polarity at low temperature only one bromine atom enters, at the ortho or the para position:
\( \displaystyle \ce{C6H5OH + Br2} \xrightarrow[\text{low temperature}]{\ce{CS2}} \ce{BrC6H4OH + HBr} \)
(C) C6H5OH + dilute HNO3 (298 K) → — This matches (II) o-Nitrophenol and p-nitrophenol. Dilute nitric acid at low temperature brings in one nitro group, at the ortho or the para position:
\( \displaystyle \ce{C6H5OH + HNO3} \xrightarrow[\text{298 K}]{\text{dilute}} \ce{O2NC6H4OH + H2O} \)
(D) C6H5OH + conc. H2SO4, then conc. HNO3 → — This matches (III) 2,4,6-Trinitrophenol (picric acid). Concentrated sulphuric acid first gives phenol-2,4-disulphonic acid; concentrated nitric acid then replaces both –SO3H groups and nitrates the other ortho position:
\( \displaystyle \ce{C6H5OH + 2H2SO4 -> C6H3(OH)(SO3H)2 + 2H2O} \)
\( \displaystyle \ce{C6H3(OH)(SO3H)2 + 3HNO3 -> C6H2(NO2)3OH + 2H2SO4 + H2O} \)
NCERT (2026-27 edition):
1. Electrophilic aromatic substitution – “… The –OH group attached to the benzene ring activates it towards electrophilic substitution. Also, it directs the incoming group to ortho and para positions in the ring as these positions become electron rich due to the resonance effect caused by –OH group.”
(ii) Halogenation – “(b) When phenol is treated with bromine water, 2,4,6-tribromophenol is formed as white precipitate.”
“(a) When the reaction is carried out in solvents of low polarity such as CHCl3 or CS2 and at low temperature, monobromophenols are formed.”
(i) Nitration – “With dilute nitric acid at low temperature (298 K), phenol yields a mixture of ortho and para nitrophenols.”
“Nowadays picric acid is prepared by treating phenol first with concentrated sulphuric acid which converts it to phenol-2,4-disulphonic acid, and then with concentrated nitric acid to get 2,4,6-trinitrophenol.”