An organic compound (A) with molecular formula `C_(8)H_(8)O` forms an orange-red precipitate with 2,4-DNP reagent and gives yellow precipitate on heating with iodine in the presence of sodium hydroxide. It neither reduces Tollens’ or Fehlings’ reagent, nor does it decolourise bromine water or Baeyer’s reagent. On drastic oxidation with chromic acid, it gives a carboxylic acid (B) having molecular formula `C_(7)H_(6)O_(2)`. Identify the compounds (A) and (B) and explain the reactions involved.

Explanation

Compound (A) forms 2, 4-DNP derivative. Therefore, it is an aldehyde or a ketone. Since it does not reduce Tollens reagent or Fehling solution (A) must be a ketone. (A) responds to iodoform test. Therefore, it should be a methyl ketone. The molecular formula of (A) indicates high degree of unsaturation, yet it does not decolourise bromine water or Baeyer.s reagent, indicating the presence of unsaturation in an aromatic ring. Compound (B), being an oxidation product of a ketone, it shoudl be a carboxylic acid. The molecular formula of (B) indicates that it should be benzoic acid. compound (A) should, therefore be a monosubstituted aromatic methyl ketone. The molecular formula of (A) indicates that it should be phenyl ketone (acetophenone)