JEE Chemistry 2023 Question with Solution

Given: We need the compound that will not produce a precipitate with $\text{AgNO}_3$.

Find: The correct option.

The reaction with $\text{AgNO}_3$ is used to test for halide ions. A precipitate of $\text{AgBr}$ forms only if bromide ion is readily released.

For bromobenzene, the $\text{C-Br}$ bond is strong because of resonance and the $sp^2$ hybridized carbon of the aryl ring. Hence, bromide ion is not readily liberated.

In contrast, benzylic bromide and allylic bromide form resonance-stabilized carbocations, so they react more readily with $\text{AgNO}_3$ to give precipitate.

The solution states that bromobenzene does not react with $\text{AgNO}_3$ to form a precipitate. However, the solution also labels the correct option as D, while the explanation matches Option 2. Since the working identifies Option 2: Bromobenzene as correct, the source has an option-label mismatch.

Therefore, the most defensible answer from the provided options is D.

Given: A precipitate with $\text{AgNO}_3$ appears when the halide ion is easily available.

Find: Which structure does not release bromide ion readily.

1. Option 1: The explanation says cyclopropyl bromide does not easily break the $\text{C-Br}$ bond.
2. Option 2: Bromobenzene is an aryl halide. Its $\text{C-Br}$ bond has partial double-bond character because of resonance, so it does not ionize readily.
3. Option 3: Benzylic bromide forms a resonance-stabilized benzylic carbocation, so precipitate forms.
4. Option 4: Allylic bromide also forms a resonance-stabilized carbocation, so precipitate forms.

Thus, from the chemical reasoning, bromobenzene is the compound that will not produce a precipitate with $\text{AgNO}_3$.

Because the source solution declares option D while the detailed explanation identifies Option 2, there is a discrepancy in the source material.