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 Baeyerâs 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

(i) Since the compound [A] gives positive DNP and iodoform tests, it must have a methyl ketonic group `(CH_(3)-CO-)`.
(ii) Since the compound [A] does not reduce Tollen's reagent or Fehling solution, it is not an aldehyde.
(iii) As the compound [A] does not decolourise bromine water, it must be saturated in nature and is expected to be an aromatic compound.
(iv) The avialable infomation shows that the compound [A] upon oxidation with chromic acid `[H_(2)CrO_(4)]` gives carboxylic acid [B] with molecular formula `C_(7)H_(6)O_(2)`. The formula is of benzoic acid which is an aromatic acid.
(v) Since [B] has been formed as a result of oxidation of compound [A], this shows that the compound which is a methyl ketone has the formula `C_(6)H_(5)-overset(O)overset(||)C-CH_(3) (C_(8)H_(8)O)` and is acetophenone.
The reaction involved are as follows: