Compound (A) `C_(6)H_(12)O_(2)` on reduction with `LiAlH_(4)` yields two compounds B and C. The compound (B) on oxidation gave (D) which on treatment with aqueous alkali and subsequent heating furnished E. The latter on catalytic hydrogenation gave (C). Compound (D) on oxidation gave monobasic acid (molecular formula weight = 60). Deduce the structure of (A), (B), (C), (D) and (E).

Explanation

E is monobasic acid `(RCOOH)` having molecular weight 60 and it is formed from D on oxidation. So E must be acetic acid and D must be acetaldehyde. (B) on oxidation gives `CH_(3)CHO`. So (B) must be alcohol `(CH_(3)CH_(2)OH)`.
Acetaldehyde (D) on treating with aqueous alkali `(NaOH)` gives aldol which on heating gives 2-butenal (E).
`underset((D))(CH_(3)CHO)overset(NaOH)rarr underset("aldol")(CH_(3)CHOHCH_(2)CHO)overset("heat")underset(-H_(2)O)rarr underset("2 - butenal (E)")(CH_(3)-CH=CHCHO`
Compound E on catalytic hydrogenation gives butyl alcohol.
`CH_(3)-CH=CHCHOoverset(H_(2))rarr underset("1 - butanol (C)")(CH_(3)CH_(2)-CH_(2)-CH_(2)OH)`
Hence compound (A) must be an ester. Ester (A) on reduction with `LiAlH_(4)` yields two alcohols (B) and (C).
A is ethyl butyrate
`CH_(3)CH_(2)CH_(2)COOCH_(2)CH_(3)overset(LiAlH_(4))rarr underset((B))underset("ethyl alcohol")(CH_(3)CH_(2)OH)+underset((C))underset("butyl alcohol")(CH_(3)CH_(2)CH_(2)CH_(2)OH)`
‘A’ can also be `CH_(3)CO-O-CH_(2)CH_(2)CH_(2)CH_(3)`. This structure will be answering all the above reactions.