Analysis of the Reaction

1. Reactant and Reagents: The starting material given is N,N-dimethyl-4-nitroaniline. The reagents are (i) NaNO₂, HCl, 0-5°C and (ii) Aniline.
2. Reaction of a Tertiary Aromatic Amine: The reactant is a tertiary aromatic amine. The conditions (NaNO₂/HCl, 0-5°C) are typically used for diazotization of primary aromatic amines. Tertiary aromatic amines do not form diazonium salts. Instead, they undergo electrophilic aromatic substitution on the electron-rich ring with the nitrosonium ion (NO⁺) generated from nitrous acid. This reaction is called C-nitrosation.
   • In N,N-dimethyl-4-nitroaniline, the -N(CH₃)₂ group is a powerful activating group and is ortho, para-directing. Since the para position is occupied by the -NO₂ group, the substitution would occur at the ortho position.
   • The product of the first step would be 2-nitroso-4-nitro-N,N-dimethylaniline.
   • This nitroso compound is not a diazonium salt and would not react with aniline in a standard azo coupling reaction to form any of the products shown in the options.

Correcting the Premise

1. Typographical Error: Given the reagents and the product options (which are all azo dyes), it is highly probable that the starting material is intended to be 4-nitroaniline, a primary aromatic amine, instead of its N,N-dimethyl derivative.
2. Proposed Reaction: Let's solve the problem assuming the starting material is 4-nitroaniline.

Step-by-Step Solution (with 4-nitroaniline)

Step 1: Diazotization

Primary aromatic amines react with nitrous acid (HONO, generated in situ from NaNO₂ and HCl) at low temperatures (0-5°C) to form a diazonium salt. 4-nitroaniline is converted to 4-nitrobenzenediazonium chloride.

$\text{p-NO}_2\text{-C}_6\text{H}_4\text{-NH}_2 \xrightarrow{\text{NaNO}_2, \text{HCl}, 0-5^\circ\text{C}} \text{p-NO}_2\text{-C}_6\text{H}_4\text{-N}_2^+ \text{Cl}^-$

Step 2: Azo Coupling

The 4-nitrobenzenediazonium ion is an electrophile. It reacts with an activated aromatic ring, in this case, aniline (C₆H₅NH₂), via an electrophilic aromatic substitution reaction. This is called azo coupling.

1. Directing Effect: The amino group (-NH₂) in aniline is a strong activating group and is ortho, para-directing.
2. Position of Attack: The electrophilic diazonium ion will attack the aniline ring.
   • Para-attack: Attack at the para position is sterically favored and leads to the major product.
   • Ortho-attack: Attack at the ortho position is sterically hindered and leads to a minor product.

Major Product Formation (Para-coupling):

$\text{p-NO}_2\text{-C}_6\text{H}_4\text{-N}_2^+ + \text{C}_6\text{H}_5\text{-NH}_2 \rightarrow \text{p-NO}_2\text{-C}_6\text{H}_4\text{-N=N-C}_6\text{H}_4\text{-NH}_2\text{-(p)} + \text{H}^+$

The structure of the major product is 4-((4-nitrophenyl)diazenyl)aniline.

Evaluation of Options

• Option A: This is the para-coupled product, 4-((4-nitrophenyl)diazenyl)aniline. This is the major product.
• Option B: This is the ortho-coupled product, 2-((4-nitrophenyl)diazenyl)aniline. This is a minor product.
• Option C: This would be the major product if the coupling agent was N,N-dimethylaniline instead of aniline.
• Option D: This compound would be formed from completely different starting materials (diazotization of p-phenylenediamine and coupling with N,N-dimethylaniline).

Since the question asks for the major product(s), and para-coupling is significantly favored, Option A is the correct answer.