MHT CET202521 Apr 2025Evening ShiftChemistryHaloalkanes and HaloarenesActual
What type of arenes are obtained when arene diazonium chloride is treated with fluoroboric acid and then heated further?
Options
- AAr - NO ₂
- BAr - F
- CAr - Cl
- DAr-H
Correct answer
B. Ar - F
Step-by-step solution
The reaction is the Balz-Schiemann reaction , which synthesizes fluoroarenes from arene diazonium salts. Arenediazonium fluoroborate forms when arenediazonium chloride ArN₂^+Cl^- reacts with fluoroboric acid HBF₄ : ArN₂^+Cl^- + HBF₄ ArN₂^+BF₄^- + HCl Thermal decomposition of arenediazonium fluoroborate produces fluoroarene ArF , nitrogen gas, and boron trifluoride: ArN₂^+BF₄^- heat ArF + N₂ + BF₃ The product is a fluoroarene ArF , corresponding to option B.