Q.How will you convert nitrobenzene into
i. 1,3,5-trinitrobenzene
ii. o- and p-nitrophenol
iii. m-nitroaniline
iv. azoxybenzene
v. hydrazobenzene
vi. N-phenylhydroxylamine
vii. aniline?

Step 1. i. TRINITROBENZENE: nitrobenzene nitrated once more (373 K) gives 1,3-dinitrobenzene (meta-directed by the first -NO2); a further, hotter nitration (473 K) then gives 1,3,5-trinitrobenzene (TNB).

Step 2. ii. o-/p-NITROPHENOL: reduce nitrobenzene (Sn/HCl) to aniline; diazotise (NaNO2/HCl, 273-278 K) to benzenediazonium chloride; hydrolyse in warm water to phenol; phenol's -OH is a strong activator, so ordinary nitration of phenol (dilute HNO3) then gives the o- and p-nitrophenol mixture, separable afterward by steam distillation (o-nitrophenol, being intramolecularly hydrogen-bonded, is more volatile).

Step 3. iii. m-NITROANILINE: nitrate nitrobenzene once more to m-dinitrobenzene, then apply the unit's own SELECTIVE reduction rule -- (NH4)2S reduces only ONE of the two -NO2 groups, giving m-nitroaniline (the second -NO2 survives untouched).

Step 4. iv./v. AZOXYBENZENE/HYDRAZOBENZENE: reducing nitrobenzene under ALKALINE conditions (Zn/NaOH, or specifically Na3AsO3/NaOH) triggers self-condensation of the partially-reduced intermediates to azoxybenzene; a further reduction (Zn/NaOH/CH3OH or LiAlH4) carries this to azobenzene, and one more reduction step (Zn/NaOH, 2[H]) carries azobenzene on to hydrazobenzene, C6H5-NH-NH-C6H5.

Step 5. vi. N-PHENYLHYDROXYLAMINE: Zn/NH4Cl (neutral medium, 4[H]) specifically halts the reduction ladder at this intermediate stage, short of the full amine. …

Sort the seven targets by which single lever controls the outcome -- nitration temperature (i), a full reduce-diazotise-hydrolyse-nitrate detour through phenol (ii), selective mono-reduction of a dinitro ring ( …

• Trying to reach o-/p-nitrophenol (ii) by nitrating nitrobenzene's OWN ring directly -- nitrobenzene's existing -NO2 is meta-directing and deactivating, so it can never itself be nitrated to a nitrophenol; the -OH has to be installed FIRST (via the anili …