Read the passage carefully and answer.

Organic compounds derived from $NH_3$ by replacing one or more H-atoms with alkyl or aryl groups will form primary, secondary and tertiary amines. The common methods which include their preparations are reduction of nitro group, amide group and nitrile group, Gabriel phthalimide synthesis and ammonolysis of alkyl halides. Amines are basic in nature due to the presence of a lone pair of electrons on the nitrogen atom. Important chemical properties of amines include acylation, alkylation and their interaction with nitrous acid. There are various tests which can distinguish different types of amines from each other, for e.g. carbylamine test, Hinsberg's test, coupling reaction etc. Another important class of compounds which can be derived from primary amines is azo compounds. These compounds are intensely colored and widely used as dyes in textile, leather and food industries.

Correctly predict the final product and the type of reaction for the following reaction:

p-Hydroxyazobenzene, Electrophilic Substitution Reaction.

The correct answer is Option (4) → p-Hydroxyazobenzene, Electrophilic Substitution Reaction.

1. Product Formation: In an alkaline medium, benzene diazonium chloride ($C_6H_5N_2Cl$) reacts with phenol ($C_6H_5OH$) to form $p$-hydroxyazobenzene. This compound is a bright orange azo dye.
2. Coupling Mechanism: This process is known as a coupling reaction. The reaction occurs at the para position of the phenol ring (relative to the $-OH$ group) because that position is highly activated and less sterically hindered.
3. Reaction Type: The coupling reaction is a classic example of electrophilic aromatic substitution.
• Electrophile: The benzene diazonium cation ($C_6H_5N_2^+$) acts as the electrophile.
• Nucleophile: The phenoxide ion ($C_6H_5O^-$), formed by the reaction of phenol with the alkaline medium ($NaOH$), acts as the nucleophile. The phenoxide ion is much more reactive than neutral phenol toward electrophilic attack.

Summary of Correct Details:

• Final Product: $p$-Hydroxyazobenzene ($C_6H_5-N=N-C_6H_4-OH$).
• Reaction Category: Electrophilic Substitution Reaction.
• Color of Dye: Orange.