Direct nitration of aniline with conc. HNO ₃ and conc. H ₂ SO ₄ at 288 K yields three products: A ( 51 % ), B ( 47 % ), and C ( 2 % ). In a separate experiment, aniline is treated with acetic anhydride in the presence of pyridine, followed by nitration with conc. HNO ₃ and conc. H ₂ SO ₄ , and finally subjected to acidic hydrolysis to yield D as the major product. Identify the products B and D respectively.

Step-by-step solution

In the direct nitration of aniline using a strongly acidic mixture of conc. HNO ₃ and conc. H ₂ SO ₄ , a significant portion of aniline is protonated to form the anilinium ion. The - NH ₃^+ group is strongly deactivating and meta-directing. As a result, along with the expected para derivative ( 51 % , product A), a large amount of the meta derivative ( 47 % , product B) is formed, with a minor amount of the ortho derivative ( 2 % , product C). Thus, B is m -nitroaniline. To obtain the para isomer almost exclusively