Final answer:
The correct reagent for converting phenol into 2, 4, 6-tribromophenol is Br₂/H₂O (option D). Phenol's aromatic ring gets brominated at the ortho and para positions due to the activation by the hydroxyl group.
Step-by-step explanation:
The reagent used for the bromination of phenol to form 2, 4, 6-tribromophenol is Br₂/H₂O (option D). Phenol, also called hydroxybenzene, is an aromatic alcohol that when treated with bromine water undergoes electrophilic substitution to yield a white precipitate of 2, 4, 6-tribromophenol. This reaction is a testament to phenol's reactivity due to the activating effect of the -OH group which directs the substitution to the ortho and para positions of the benzene ring.
Phenol itself is a volatile, white crystalline solid with a distinctive odor and exhibits slight acidity in water, reacting with sodium hydroxide to form salts. In comparison, picric acid, another derivative of phenol known as 2,4,6-trinitrophenol, contains three nitro groups instead of bromine atoms.