JEE Main · 2026 · 04 Apr 2026 · Shift 1 · Compounds Containing Nitrogen

Aniline is strongly activating, so bromine water substitutes at all three positions ortho and para to the amino group, giving 2,4,6-tribromoaniline (A). Diazotisation of A with $\mathrm{NaNO}{}_2/\mathrm{HCl}$ at 273--278 K gives 2,4,6-tribromobenzenediazonium chloride (B). Converting this to the diazonium fluoroborate with $\mathrm{HBF}{}_4$ and then treating it with $\mathrm{NaNO}{}_2$ in the presence of copper replaces the diazonium group by a nitro group. The nitro group thus takes the carbon that originally bore the amino group while the three bromines remain, giving 1,3,5-tribromo-2-nitrobenzene.