The Wolff-Kishner reduction, discovered by Nicolai Kishner and Ludwig Wolff, reduces carbonyl compounds to hydrocarbons using hydrazine and a base, with nitrogen gas as a byproduct. This method converts carbonyl groups into methylene groups and finds applications in creating polycyclic aromatics as well as reducing aliphatic and mixed carbonyl compounds. However, it requires high temperatures and can sometimes lead to undesired products due to double bond migration.

1. P R E S E N T E D B Y
K . M U T H U K A N N A N

2. WOLFF-KISHNERREDUCTION:
The Wolff Kishner reduction was discovered by
Nicolai Kishner in 1911 and Ludwig Wolff in 1912.It involves the
reduction of carbonyl compounds to hydrocarbon by heating with
hydrazine and a base. In this process the carbonyl group is
converted to methylene group and nitrogen gas evolves out, which
is a side product of reaction and ethylene glycol is used as a solvent.

3. Mechanism:

5. Exambles:

6. Applications:
C6H5 C
O
C3H5
Zn/Hg
Conc.HCl
C6H5 CH2 C3H5
H3C (CH2)5 CHO
Zn/Hg
HCl
H3C (CH2)5 CH3
Heptanol Heptane
⸙ This reaction has widely used to convert a carbonyl group into
methylene group.
⸙ Also important application in the preparation of polycyclic
aromatics and aromatics containing unbranched side hydrocarbon
chains.
⸙ To reduce aliphatic and mixed aliphatic-aromatic carbonyl
compounds.

7. limitations:
The reduction requires a high temperature.
Although the process is specific for carbonyl
groups, sometimes migration of the double bond takes
place instead of the expected mechanism of the reaction
when undesired product like alpha, beta-unsaturated
carbonyl compounds are formed in the reaction.