Question

What is the product of the reaction of aniline with a mixture of conc. $HN{{O}_{3}}$ and conc. ${{H}_{2}}S{{O}_{4}}$ ?
(A) o- and p-nitroaniline
(B) m-nitroaniline
(C) a black tarry substance
(D) There is no reaction.

Answer 1

Hint: Nitration is the process of substitution of one or more nitro groups by a hydrogen atom, which is an organic molecule. Due to the exothermic nature of this reaction, it takes place at high temperatures. A lot of heat is produced during large-scale nitration processes.

Complete Step by Step Solution:
The nitration of aniline is an electrophilic substitution reaction in which a mixture of ortho-, para-, and meta-nitroanilines is formed. Because of steric factors, only about 2% of the ortho-nitroaniline is formed. $HN{{O}_{3}}$, which is a strong oxidising agent, causes aniline to produce tarry oxidation products along with certain other oxidation products. It is impossible to nitrate aniline without preserving the amino group since $HN{{O}_{3}}$is a strong oxidising agent that oxidises aniline.
Correct option (C) a black tarry matter.

Additional Information: Aniline is a viscous, musty liquid that varies in colour from yellow to brown. It is denser than water and therefore insoluble in water. Aniline vapours are denser as compared to air. It is a weak base and reacts with strong acids to form an anilinium ion.

Note: Sulfuric acid is crucial for this reaction because it protonates nitric acid, which results in the loss of a water molecule and the production of the electrophilic nitronium ion. The benzene ring is then attacked by this nitronium ion further, leading to nitration.