Question

An organic compound A has molecular formula C₇₉N and it forms a clear solution when dissolved in aqueous KOH solution of benzene sulphonyl chloride. A on treatment with NaNO₂ and HCl at 0°C and then with 2-naphthol form an intensely coloured compound. Aslo A on treatment with CH₃COCl followed by electrophilic sustitution yields a single product. identify A

A. 4-emthylaniline
B. 2-methylaniline
C. 3-methylaniline
D. N-methylaniline

Answer 1

The organic compound A with molecular formula C₇H₉N that forms a colored compound upon reaction with NaNO₂ and HCl, followed by 2-naphthol, and yields a single product with CH₃COCl is N-methylaniline.

Step-by-step explanation:

The organic compound in question is N-methylaniline. When A reacts with benzene sulphonyl chloride in the presence of aqueous KOH, it forms a clear solution indicating its basic nature, characteristic of anilines. Furthermore, its reaction with NaNO₂ and HCl, followed by 2-naphthol, forms an intensely colored compound, which is typical for the formation of an azo dye, a reaction commonly known for primary aromatic amines.

The fact that it yields a single product upon reaction with CH₃COCl and subsequent electrophilic substitution confirms that there are no additional reactive ortho or para positions on the benzene ring. Since N-methylaniline is aniline with a methyl group (-CH₃) attached to the nitrogen, there is only one possible position for an electrophilic substitution, which is the para-position relative to the amino group.