Question

Aryl diazonium reacts with fluoroborate to give aryl fluoride:

• A. Balz-Schiemann reaction
• B. Stephen reaction
• C. Gattermann reaction
• D. Gomberg reaction

Hint:

Remember: Balz-Schiemann reaction is the key method to prepare aryl fluorides from aryl diazonium salts — an important named reaction for GPAT organic chemistry.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The question describes converting an aryl diazonium fluoroborate salt into an aryl fluoride, and asks us to name this reaction.

Step 2: Key Formula or Approach:
\[ Ar\text{-}N_2^{+}BF_4^{-} \xrightarrow{\Delta} Ar\text{-}F + N_2 + BF_3 \]
A reaction that fits this exact pattern, thermal breakdown of an aryl diazonium tetrafluoroborate to give the aryl fluoride, is named the Balz-Schiemann reaction.

Step 3: Detailed Explanation:
The aryl diazonium salt is first exchanged with tetrafluoroborate ion to precipitate the stable diazonium fluoroborate salt out of solution.
This solid salt is dried and then gently heated, which drives off nitrogen gas and boron trifluoride gas.
The fluoride ion that is left behind bonds directly to the aromatic carbon that originally held the diazonium group, giving the aryl fluoride.
This is the main way chemists introduce a single fluorine atom onto an aromatic ring, since direct fluorination with fluorine gas is too violent to control safely.

Step 4: Final Answer:
The reaction is the Balz-Schiemann reaction.