Question

Aniline reacts with conc. $\;{\text{HN}}{{\text{O}}_{\text{3}}}$ to give:-

Answer 1

We must remember the reactivity of aniline. If we react to aniline with conc. $\;{\text{HN}}{{\text{O}}_{\text{3}}}$ we will get benzoquinone. Because concentrate nitric acid is a strong oxidising agent which oxidises the amine group into carbonyl compounds in benzene rings.

Complete step by step answer:
In the presence of concentrated nitric acid, aniline gets oxidised to give p-benzoquinone.

Generally in the presence of nitric acid and sulphuric acid, aniline forms anilinium nitrate as an intermediate product and forms azobenzene nitrate.
Hence, option C is the correct answer.
** Additional Information:-**
1. Aniline is a light brownish oily liquid with a musty and smells like the odour of a rotten fish. It is a flammable liquid and has an unpleasant odour. The compound is soluble in water. Aniline has a boiling point of $184^oC$ and melting point of about $-6^oC$ .
2. Basicity of aniline
Aniline is a weak base. They react with strong acids to form anilinium (or phenylammonium) ion$\left( {{C_6}{H_5} - N{H_3}^ + } \right)$.
Therefore, aniline when treated with a mixture of sulphuric acid and nitric acid gives a mixture of o-, m- and p- nitroaniline.

3. Since aniline is a base, it is used to make dyes, drugs, explosives, plastics, and photographic and rubber chemicals. It is used in the large-scale production of drugs such as paracetamol, Tylenol, acetaminophen. It is also used as a pesticide and fungicides in the agricultural industry.

Note:
1. Instead of conc. nitric acid, a mixture of sulphuric acid and potassium dichromate can also be used to oxidise aniline into p-benzoquinone
2. Benzoquinone is used as a hydrogen acceptor and an oxidant in much important organic synthesis. 1,4-Benzoquinone is employed as a dehydrogenation reagent. It also serves as a dienophile in Diels Alder reactions. It is also used to suppress double-bond migration during olefin metathesis reactions.