Anorganic compound (A) having molecular formula `C_9H_10O` forms an orange red precipitate (B) with 2,4-DNP reagent. Compound (A) gives a yellow precipitate (C) When heated in the presence of iodine and NaOH alongwith a colourless compound (D). (A) does not reduce Tollens' reagent or Fehling solution nor does it decolourise bromine water. On drastic oxidation of (A) with chromic acid, a carboxylic acid (E) of molecular formula `C_7H_6O_2` is formed. Deduce the structures of the organic compounds (A) to (E ).

Explanation

(i) Since the compound (A) forms 2,4-DNP derivative, it is an aldehyde or ketone.
(ii) Since the compound does not reduce Tollens. or Fehling.s reagent, (A) must be ketone.
(iii) Since (A) responds to iodoform test, therefore, it should be a methyl ketone.
(iv) The molecular formula of (A) indicates high degree of unsaturation, yet it does not decolourise bromine water. This indicates unsaturation due to the presence of an aromatic ring.
(v) Compound (E), being an oxidation product of ketone, should be an acid. The molecular formula of (E) indicates that it should be benzoic acid and compound (A) should, therefore, be a monosubstituted methyl ketone. The molecular formula of (A) indicates that it should be phenylpropanone which on drastic oxidation gives colourless benzoic acid. Reactions may be explained as follows:

(A) On reaction with NaOH and `I_2`, forms yellow coloured `CHI_3` (iodoform).

(A) On drastic oxidation gives benzoic acid because any side chain, irrespective of its length, gets oxidised to COOH.