Give reasons for any 3 of the following observations:

(a) Which type of reagent is a good choice for reducing an aryl nitro compound to an amine?

(b) In the reduction of nitro compounds, why Fe scrap and HCl is preferred over other metals?

(c) Acetylation of aniline reduces its activation effect.

(d) Although, -NH₂ is o/p-directing group, yet aniline on nitration gives a significant amount of m-nitroaniline. 

a) The Following reagent are good choices for reducing an aryl nitro compound to an amine.

(b) Reduction with Fe scrap and HCl is preferred over other metals as the reaction leads to the formation of FeCl₂ which gets hydrolyzed to release HCl. So, the amount of HCL needed is less.

(c) The lone pair of electrons on the N-atom is attracted because the acetyl group has an electron-withdrawing effect. N-atom at benzene ring, its lone pair of electrons is not available donation as activating effect of –NH₂ group is reduced. 

(d) In nitration, a mixture of conc. HNO₃ and conc. H₂SO₄ as a reagent.

      i. Aniline gets protonated to form anilinium ion.

      ii. Reaction mixture: Have aniline and anilinium ions.

      iii. NH2 group in aniline is o, p-directing and activating

      iv. NH₃ group in anilinium is m-directing and deactivating.

      v. Nitration of aniline gives p-nitroaniline due to steric hindrance at o-position.

      vi. The nitration of anilinium ion gives m -nitroaniline.