Aniline is subjected to: (i) $(\mathrm{CH}{}_3\mathrm{CO}){}_2\mathrm{O}$ / pyridine; (ii) $\mathrm{Br}{}_2$ in ethanoic acid (1 equiv.); (iii) dilute $\mathrm{HCl}$, heat (hydrolysis); (iv) $\mathrm{NaNO}{}_2$ / dil. $\mathrm{HCl}$, 273-278 K; (v) $\mathrm{CuCN}/\mathrm{KCN}$. The major final product is

Acetylation moderates the activating effect, so monobromination of acetanilide occurs mainly para (steric hindrance disfavours ortho). Hydrolysis gives 4-bromoaniline, diazotisation gives 4-bromobenzenediazonium chloride, and Sandmeyer cyanation replaces $\mathrm{N}{}_2{}^{+}$ by $\mathrm{CN}$ at the same carbon: 4-bromobenzonitrile.