Question

Q. 2. Wolff-Kishner reduction is
A) reduction of carbonyl compounds into hydrocarbons
B) reduction of carbonyl compounds into alcohol
C) reduction of nitrobenzene into aniline
D) reduction of carbohydrates into alcohol​

Answer 1

Answer:

A) Reduction of carbonyl compounds into hydrocarbons

Explanation:

$\large{ \bf{ \underline{Wolff-Kishner \: reduction}:}}$

Carbonyl group of aldehyde or ketone is heated with hydrazine followed by heating with KOH in boiling solvent such as ethylene glycol to give methylene group.

$\rm CH_3CH = O + H_2 - N - NH_2 \xrightarrow{-H_2O} CH_3CH = N.NH_2 \xrightarrow{KOH/ ethylene \ glycol} CH_3CH_3 + N_2$

$\rm CH_3COCH_3 + NH_2.NH_2 \xrightarrow{-H_2O} CH_3CN.NH_2CH_3 \xrightarrow{KOH/ ethylene \ glycol} CH_3CH_2CH_3 + N_2$

Additional Information:

Reduction of Carbonyl group to methylene group to form hydrocarbons

$\bf{\underline{Clemmensen \ reduction}:}$

Reduction with Zn-Hg (amalgam) and concentrated HCl

$\rm CH_3CHO + 4[H] \xrightarrow[HCl]{Zn-Hg} CH_3 CH_3 + H_2O$

$\rm CH_3COCH_3 + 4[H] \xrightarrow[HCl]{Zn-Hg} CH_3 CH_2 CH_3 + H_2O$

$\bf{\underline{Reduction \ with \ Red \ P \ and \ HI \ at \ 420 \ K}:}$

$\rm CH_3CHO + 4HI \xrightarrow[\Delta]{Red \ P} CH_3 CH_3 + H_2O + 2I_2$

$\rm CH_3COCH_3 + 4HI \xrightarrow[\Delta]{Red \ P} CH_3 CH_2 CH_3 + H_2O + 2I_2$

Answer 2

A) reduction of carbonyl compounds into hydrocarbons