MHT CET202522 Apr 2025Morning ShiftChemistryAminesActual
Which from following reaction results in azo coupling?
Options
- AC ₆ H ₅ NH ₂ HNO ₂
- BC ₆ H ₅ ~N ₂ Cl + C ₆ H ₅ OH OH ⁻
- CC ₆ H ₅ ~N ₂ Cl HBF ₄
- DC ₆ H ₅ ~N ₂ Cl [ HCl ] Cu (Powder)
Correct answer
B. C ₆ H ₅ ~N ₂ Cl + C ₆ H ₅ OH OH ⁻
Step-by-step solution
Azo coupling is an electrophilic aromatic substitution reaction involving an arenediazonium salt and an electron-rich aromatic compound like phenol or aniline, forming an azo compound with the -N=N- linkage, often used as dyes. A: Aniline reacts with nitrous acid to form benzenediazonium chloride ( C₆H₅N₂^+Cl^- ). This is diazotization, producing a precursor, not azo coupling: C₆H₅NH₂ + HNO₂ + HCl 0-5^ C C₆H₅N₂^+Cl^- + 2H₂O . B: Benzenediazonium chloride reacts with phenol in alkaline medium, coupling at the para-p