Q.Nitrobenzene is catalytically hydrogenated using $\text{H}_2/\text{Pd-C}$. Identify the product and state one advantage of this method over $\text{Sn}/\text{HCl}$ reduction on an industrial scale.

$\text{H}_2$ over a $\text{Pd-C}$ catalyst delivers hydrogen atoms directly to the nitro group, carrying it fully through to the amine: $\text{C}_6\text{H}_5\text{NO}_2 + 3\text{H}_2 \xrightarrow{\text{Pd-C}} \text{C}_6\text{H}_5\text{NH}_2 + 2\text{H}_2\text{O}$. Unlike $\text{Sn}/\text{HCl}$ or $\text{Fe}/\text{HCl}$, which consume the metal stoichiometrically and leave behind large volumes of metal-salt sludge that must be filtered and disposed of, catalytic hydrogenation uses only a small, reusable a …

Recognise catalytic hydrogenation as a full reduction to the amine, then compare its by-product profil …

Assuming catalytic hydrogenation gives a different (partial) product from $\text{Sn}/\text{HCl}$ -- …