An aromatic compound (A), on treatment with a saturated solution of sodium bisulphite, produced a solid crystalline product. (A) gave a compound (B) and a sodium salt of an aromatic monobasic acid (C ) on treatment with alkali. (B) contained 77.8% C and 7.4% H and rest, oxygen. The sodium salt on distillation with soda lime gave benzene. If (B) may be oxidised with KMnO_(4) to (C ), find the structural formulae of (A), (B) and (C )

An aromatic compound (A), on treatment with a saturated solution of so

1.	An aromatic compound (A), on treatment with a saturated solution of sodium bisulphite, produced a solid crystalline product. (A) gave a compound (B) and a sodium salt of an aromatic monobasic acid (C ) on treatment with alkali. (B) contained 77.8% C and 7.4% H and rest, oxygen. The sodium salt on distillation with soda lime gave benzene. If (B) may be oxidised with KMnO_(4) to (C ), find the structural formulae of (A), (B) and (C )
Answer» Solution :For the compound (B): Moles of `C: H: O = (77.8)/(12): (7.4)/(1): (14.8)/(16)` `=6.48: 7.4: 0.925` `=7:8:1` `therefore` EMPIRICAL formula of (B) is `C_(7)H_(8)O` The reaction sequence given may be represented as (A) is an aromatic aldehyde as it FORMS crystalline product with `NaHSO_(3)`. Sodium salt of (C ), on distillation with soda lime gives `C_(6)H_(6)`, so (C ) must be `C_(6)H_(5)COOH`. Further, since (C ) is produced by the oxidation of (B), it must be a homologue of `C_(6)H_(6)` or some compound containing an easily oxidisable side chain. From the formula of (B), it must be `C_(6)H_(5).CH_(2)OH` (benzyl alcohol). Again, since `C_(6)H_(5).CH_(2)OH` (B) and `C_(6)H_(5)COOH` (C ) are produced from (A) on treatment with alkali, (A) must be `C_(6)H_(5)CHO` (benzaldehyde) (Cannizzaro reaction).