JEE Chemistry 2023 Question with Solution

Given: N,N-dimethylaniline (A) reacts with $\text{NaNO}_2$ and $\text{HX}$ to form B.

Find: The incorrect statement regarding this reaction.

Explanation:

The electrophile generated in the reaction medium is $\text{NO}^+$. This reaction is carried out at low temperature. In tertiary aromatic amines such as N,N-dimethylaniline, electrophilic substitution occurs on the ring and the major product formed is the $p$-nitroso compound.

Therefore, the statement saying that B is an N-nitroso ammonium compound is incorrect. The solution marks D as correct, but its own explanation shows that statement (2) is incorrect. Hence there is a source discrepancy, and the defensible incorrect statement is option B.

Given: The substrate is a tertiary aromatic amine, N,N-dimethylaniline.

Find: Which statement does not match the chemistry of nitrosation under acidic conditions.

For tertiary aromatic amines, nitrosonium ion attacks the aromatic ring, mainly at the para position, rather than giving an N-nitroso ammonium product.

So:

1. The electrophile is $\text{NO}^+$ — correct.
2. The reaction is done at low temperature — correct.
3. The product is a $p$-nitroso derivative at low temperature — correct.
4. Saying B is an N-nitroso ammonium compound is incorrect.

Therefore, the chemically correct answer is option B.