How will you convert ethanal into the following compounds?
(i) Butane-1,3-diol
(ii) But-2-enal
(iii) But-2-enoic acid

Explanation

(i) Ethanal to butane-1, 3-diol
`underset("Ethanal")underset()underset()(CH_(3))CHOoverset(NaOH)underset(("Aldol condensation"))rarrunderset("3-Hydroxybutanal")(overset(4)CH_(3)underset("OH ")underset("| ")overset("3 ")(CH)overset(2)CH_(2)overset(1)CHO)overset(LiAIH_(4))rarrunderset("Butane-1,3-diol")(overset(4)CH_(3)underset("OH ")underset("| ")overset("3 ")(CH)overset(2)CH_(2)underset("OH ")underset("| ")overset("1 ")(CH_(2)`
(ii) Ethanal to but-2-enal
`underset("Ethanal")underset()underset()(2CH_(3))CHOoverset(NaOH)underset(("Aldol condensation"))rarrunderset("3-Hydroxybutanal")(overset(4)CH_(3)underset("OH ")underset("| ")overset("3 ")(CH)overset(2)CH_(2)overset(1)CHO)overset("Heat")underset(-H_(2)O)rarrunderset("But-2-enal")underset()underset()(overset(4)CH_(3)overset(3)CH=overset(2)CHoverset(1)CHO`
(iii) Ethanal into but-2-eonic acid
`underset("Ethanal")underset()underset()(2CH_(3))CHOoverset("As in" (ii))rarrunderset("But-2-enal")underset()underset()(overset(4)CH_(3)overset(3)CH=overset(2)CHoverset(1)CHO)overset("Tollen's reagent")underset(or MnO_(2))rarr underset("But-2-enoic acid")underset()underset()(CH_(3)-CH-CHCOOH`
Note. Both Tollen's reagent and `MnO_(2)` are weak oxidising agents. These oxidise only the aldehydic group without affectting the double bond.