An organic compound A `(C_(7)H_(6)O)` forms a bisulphite. A when treated with alcoholic KCN forms B `(C_(14)H_(12)O_(2))` and A on refluxing with sodium acetate and acetic anhydride forms an acid C `(C_(9)H_(8)O_(2))`. Identify A, B and C. Explain the conversion of A to B and C.

Explanation

(i) An organic compound (A) with formula `C_(7)H_(6)O` form bisulphite means it must be benzaldehyde `C_(6)H_(5)CHO`.
(ii) Benzaldehyde on treatment with KCN form benzoin.
`underset((A))(C_(6)H_(5)CHO+C_(6)H_(5)CHO)overset(KCN)tounderset((B))(C_(6)H_(5)-underset(HO)underset(|)(CH)-underset(O)underset(||)(C)-C_(6)H_(5))`
(iii) Benzaldehyde on treatment with sodium acetate and acetic anhydride form an acid, cinnamic acid it is ( C).
`underset((A))(C_(6)H_(5)CHO)+(CH_(3)CO)_(2)Ooverset(CH_(3)COONa)tounderset((C))(C_(6)H_(5)CH=CH-COOH)+CH_(3)COOH`