Compound (A) `(C_(6)H_(12)O_(2))` on reduction with `LiAlH_(4)` yielded two compounds (B) and (C ). The compound (B) on oxidation gave (D), which on treatment with aqueous alkail and subsequent heating furnished (E ). The latter on catalytic hydrogenation gave (C ). The compound (D) was oxidised further to give (F) which was found to be a monobasic acid (molecular formula weight `= 60.0`). Deduce the structures of (A), (B), (C ), (D), and (E ).

Explanation

(i) The compound [F] being a monobasic acid may be represented as RCOOH. As the molar mass of acid [F] is 60, the alkyl group [R] must be methyl group `(-CH_(3))`. This is calculated by subtracting the mass of -COOH group (45) from that of the acid i.e. 60-45=15 and this is the mass due to `CH_(3)` group. Thus, [F] is `CH_(3)COOH`.
(ii) Since the compound [F] is obtained by the oxidation of [D] the compound [D] must be aldehyde i.e. `CH_(3)CHO`.
(iii) The compound [D] was obtained by the oxidation of [B] which must be an alcohol with structure `CH_(3)CH_(2)OH`.
(iv) The compound [D] on treatment with alkali gave alcohol which when heated produced [E] as follows :
`underset("Ethanal"[D])underset()underset()(2CH_(3)CHO)overset(KOH(aq.))rarrunderset("2-Hydroxybutanal")underset()(CH_(3)underset(OH)underset(|)CHCH_(2)CHO)overset("heat")underset(-H_(2)O)rarrunderset("But-2-enal[E]")underset()underset()(CH_(3)CH=CHCHO)`
(v) The compound [E] on acatalytic hydrogenation give [C], `underset([E])underset()(CH_(3)CH=CHCHO)overset(H_(2)//Ni)rarrunderset("Butan-1-01[C]")underset()(CH_(3)CH_(2)CH_(2)CH_(2)OH)`
(vi) Since the compound [A] when reduced with `LiAIH_(4)` gave the compound [B] and [C], it must be an ester i.e. ethylbutanoate.
`underset("Ethylbutanoate [A]")underset()underset((C_(6)H_(12)O_(2)))underset()(CH_(3)CH_(2)CH_(2)COOCH_(2)CH_(3))overset(LiAIH_(4))rarrunderset("Butan-1-01[C]")underset()(CH_(3)CH_(2)CH_(2)CH_(2)OH)+underset("Ethanol [B]")underset()(CH_(3)CH_(2)OH)`