Question

(a) Write the chemical reaction involved in Wolff-Kishner reduction.

(b) Arrange the following in the increasing order of their reactivity towards nucleophilic addition reaction.

C₆H₅COCH₃,CH₃ - CHO,CH₃COCH₃

(c) A and B are two functional isomers of compound C₂H₆O. On heating with NaOH and I₂, isomer B forms yellow precipitate of iodoform whereas isomer A does not form any precipitate. Write the formulae of A and B.

Answer 1

(a) Wolf-Kishner reduction reaction :- The carbonyl group of aldehydes and ketones is reduced to CH₂ group on treatment with hydrazine followed by heating with potassium hydroxide in a high boiling solvent such as ethylene glycol.

(b) Increasing order of reactivity towards nucleophilic addition reaction : 

C₆H₅COCH₃ < CH₃COCH₃ < CH₃CHO

(c) Formula of compounds A and B = C₃H₆O  B forms yellow precipitate of iodoform. Hence, B must contain —COCH₃ group. Therefore,

compound ‘B’ must be 

A does not give iodoform test and it is functional isomer of B thus, it may be CH₃CH₂CHO.