(A), (B), and (C) are three non-cyclic functional isomers of a carbonyl compound with molecular formula C4H8O. Isomers (A) and (C) give a positive Tollen's test whereas isomer (B) does not give Tollen's test but gives a positive Iodoform test. Isomers (A) and (B) on reduction with Zn(Hg)/conc. HCl give the same product (D). Write the structures of (A), (B), (C), and (D).

(B) does not give Tollens' test but gives a positive Iodoform test. Hence, (B) is a methyl ketone. (A) and (C) give positive Tollens' test. Hence, they are aldehydes. Isomers (A) and (B) on reduction with Zn(Hg)/conc. HCl give the same product (D). It is an example of Clemmensen reduction in which the carbonyl group is reduced to a methylene group.

The structures are:

(A) CH3CH2CH2CHO (Butanal)
(B) CH3COCH2CH3 (Butanone)
(C) CH3CH(CH3)CHO (2-Methylpropanal)
(D) CH3CH2CH2CH3 (Butane)