Question

Compound from the following that will not produce precipitate on reaction with Compound from the following that will not produce precipitate on reaction with AgNO₃ is:

• A.

  

• B.

  

• C.

  

• D.

  

Answer 1

The Correct Option is D

The reaction with \( \text{AgNO}_3 \) is used to test for halide ions. A precipitate of \( \text{AgBr} \) (pale yellow) will form if a bromide ion is available to react with \( \text{Ag}^+ \).

Analysis of the Options:

Option 1: Cyclopropyl bromide

• The \( \text{C-Br} \) bond in cyclopropyl bromide is not easily broken.
• The carbocation \( \text{C}^+_3 \) formed upon the removal of bromide is stabilized by aromatic nature.
• Hence, it does not readily form a precipitate with \( \text{AgNO}_3 \).

Option 2: Bromobenzene

• The \( \text{C-Br} \) bond in aryl halides is strong due to resonance and the \( \text{sp}^2 \) hybridization of carbon.
• This bond does not readily break to release bromide ions.
• The carbocation \( \text{C}^+_2 \) is not formed as it is highly unstable.
• Thus, bromobenzene does not react with \( \text{AgNO}_3 \) to form a precipitate. 

Option 3: Benzylic bromide

• In benzylic bromide, the benzylic carbocation formed after the removal of bromide ion is stabilized by resonance with the benzene ring.
• This makes the bromide ion readily available to react with \( \text{Ag}^+ \), forming a precipitate.

Option 4: Allylic bromide

• In allylic bromide, the allylic carbocation formed is stabilized by resonance.
• This allows the bromide ion to react with \( \text{Ag}^+ \), forming a precipitate.

Conclusion:

Final Answer: Bromobenzene will not produce a precipitate with \( \text{AgNO}_3 \).