Question

Compound $( A ), C_8H_9Br$ gives a white precipitate when warmed with alcoholic $AgNO_3$. Oxidation of $(A)$ gives an acid $(B)$, $C_8H_6O$ 4. $(B)$ easily forms anhydride on heating. Identify the compound $(A)$.

• A.

  

• B.

  

• C.

  

• D.

  

Answer 1

The Correct Option is D

To identify compound (A), C_8H_9Br, we need to analyze the properties mentioned in the problem:

1. Compound (A), C_8H_9Br, gives a white precipitate when warmed with alcoholic AgNO_3. This indicates the presence of an alkyl or aryl halide, particularly one with a bromine substituent that can easily participate in a nucleophilic substitution reaction to form AgBr, a white precipitate.

2. The oxidation of (A) yields an acid (B), C_8H_6O. This suggests that the compound (A) contains a functional group that can be oxidized to a carboxylic acid.

3. Acid (B), C_8H_6O, easily forms an anhydride upon heating. Such behavior is typical of phthalic acids, which are benzenedicarboxylic acids capable of losing water molecules to form an anhydride.

Considering these points, compound (A) must be benzyl bromide (C₇H₇Br).

When benzyl bromide is oxidized, it undergoes oxidation to form benzoic acid (B). Benzoic acid can easily form an anhydride, consistent with the behavior described in the problem. Therefore, the correct identification of compound (A) is benzyl bromide.

Conclusion: The compound (A), C_8H_9Br, is benzyl bromide, as it meets all the given conditions.