(a) Write the chemical reaction involved in Wolf-Kishner reduction.
(b) Arrange the following in the increasing order of their reactivity towards nucleophilic addition reaction :
`C_(6)H_(5)COCH_(3), CH_(3)-CHO, CH_(3)COCH_(3)`
(c) Why carboxylic acid does not give reactions of carbonyl group ?
(d) Write the product in the following reaction.
`CH_(3)CH_(2)CH=CH-CH_(2)CN overset(1.(i-Bu)_(2)"AlH")underset(2. H_(2)O)(to)`
(e) A and B are two functional isomers of compound `C_(3)H_(6)O`. On heating with NaOH and `I_(2)`, isomer B forms yellow precipitate of iodoform whereas isomer A does not form any precipitate. Write the formulae of A and B.

Explanation

(a) `R-CHunderset("Aldehyde")( = O) overset(NH_(2)NH_(2))(to)R-underset("Hydrazone")(CH="NNH"_(2)) overset(KOH, "glycol")underset(453-473)(to)underset("Alkane")(R-CH_(3))+N_(2)`
`CH_(3)underset("Acetone")(COCH_(3)) overset(NH_(2)NH_(2)KOH)underset("Glycol " 453-473K)(to)CH_(3)underset("Propane")(CH_(2)CH_(3)) + H_(2)O`
(b) `CH_(3)CHO gt CH_(3)COCH_(3) gtC_(6)H_(5)COCH_(3)`
acetaldehyde is more reactive towards nucleophilic addition reaction because it is less sterically hindered and it has less alkyl group which make carbon more available for nucleophile.
(c) Due to the presence of pairs to `e^(-)` on the oxygen atom of the OH group, the carboxylic acids may be regarded as resonance hybrid of structures.
`R-overset(underset(||)(O))(C)-OH harr R-overset(|)(O)(C)-O^(+)-H`
Whereas, in aldehyde and ketones due to resonance carbonyl carbon carries (+) ve change. Hence, it is more electrophilic in nature than carbonyl carbon in carboxylic group. Hence carboxylic acid don't give all the carbonyl reactions (nucleophilic addition reaction)
(d) `CH_(3)CH_(2)CH=CH-CH_(2)CN overset((i-Bu)_(2)"AIH")underset(H_(2)O)(to)CH_(3)CH_(2)CH=CHCH_(2)CHO`
(e) `A=CH_(3)CH_(2)CHO`
`B=CH_(3)COCH_(3)`
`CH_(3)CH_(2)CHO + NaOH +I_(2) to "No reaction"`
`underset(("Propanone"))(CH_(3)overset(underset(||)(O))(C)-CH_(3))+NaOH + I_(2) to underset(("Yellow ppt"))(CH_(3)COONa) + CHI_(3)`