Answer:
See explanation
Step-by-step explanation:
The formation of an azo dye from p-nitrobenzenediazonium hydrogen sulfate and 8-anilino-1-naphthalenesulfonic acid occurs through a diazo coupling reaction. The mechanism is as follows:
Step 1: Formation of the diazonium salt
p-nitroaniline is first diazotized using nitrous acid to form p-nitrobenzenediazonium ion (ArN2+).
ArNH2 + HNO2 + H2SO4 → ArN2+ + 2H2O + HSO4-
Step 2: Formation of the coupling partner
8-anilino-1-naphthalenesulfonic acid acts as the coupling partner. It is deprotonated by a base such as NaOH to form the anilinonaphthalene sulfonate anion (Ar'SO3-).
Ar'SO3H + NaOH → Ar'SO3- + H2O + Na+
Step 3: Coupling of the diazonium ion and coupling partner
The diazonium ion attacks the coupling partner, and a nitrogen-nitrogen (N-N) double bond is formed to produce the azo dye.
ArN2+ + Ar'SO3- → ArN=N-Ar'SO3- + H+
The azo dye that is formed is typically orange or red in color, depending on the specific coupling partners used.