Aniline on reaction with bromine water gives 2,4,6-tribromoaniline (A) as the major product due to the strong activating nature of the −NH2 group.
Reaction of (A) with NaNO2/HCl at 273−278 K (diazotization) yields 2,4,6-tribromobenzenediazonium chloride (B).
Treatment of (B) with HBF4 forms 2,4,6-tribromobenzenediazonium fluoroborate. Heating this intermediate with NaNO2 and Cu replaces the diazonium group with a nitro group, forming 2,4,6-tribromonitrobenzene (C).
To assign the IUPAC name, we number the ring to give the lowest locant set to the substituents. The set (1, 2, 3, 5) is lower than (1, 2, 4, 6). Therefore, the nitro group is at position 2, and the bromo groups are at positions 1, 3, and 5. The correct IUPAC name is 1,3,5-tribromo-2-nitrobenzene.
Answer: 1, 3, 5-Tribromo-2-nitrobenzene