Wolff kishner reduction

1. ORGANIC CHEMISTRY 3.71
Cl
Cl
Cl
P
O
H
N
Me
Me
O Cl
Cl
Cl
P
O
H
+
+ +
−
N
Me
Me
Cl
H
−H+
−H+
−Cl−
O
Cl
H
H Cl
Me2N
Me2N
+H2O
Cl
Iminium salt
Vilsmeier reagent
P
O
O
H
+
+
−
N
Me
Me
Cl
O H
H
Me2NH
Cl
H H
Me2N O
+ Me2NH
H
O
23. Wolff-Kishner Reduction
Condensation of the carbonyl compound with hydrazine
forms the hydrazone, and treatment with base induces
the reduction of the carbon coupled with oxidation of the
hydrazine to gaseous nitrogen, to yield the corresponding
alkane. The wolff Kishner reduction yield aldehydes and
ketones to alkanes.
O
NH2NH2 .NaOH
−H2O
H
H
Reaction Mechanism
In the mechanism, hydrazine molecule act as a neucleo-
phile and attack on carbonyl carbon of ketone and by loosing
O
H2NNH2
−H2O
−
OH
−H2O
H
N
N
H
−
−
H
N
N
−
−
−
−
OH
−H2O
H
H2O
− −
OH
H2O
− −
OH
H
N
N
−
−
−
−
−
C
H
−
−
C
H
−N2
N
N
−
−
H
−
N
N
−
−
−
H
H
Wolff-Kishner Reduction
The wolff Kishner reduction yield aldehydes and
ketones o alkanes.
Condensation of the carbonyl compound with hydrazine NH2NH2 .NaOH
hydrazone, and treatment with base induces
the reduction of the carbon coupled with oxidation of the
hydrazine to gaseous nitrogen,
hydrazine molecule act as a neucleo-
phile a d attack on carbonyl carbon of ketone a

2. 3.72 CHAPTER 2
Reaction Mechanism: Nucleophilic Addition then
Elimination
In the mechanism the first step is an addition of the phos-
phorous ylide to the carbonyl icarbon of Aldehyde/ketone
lead to the zwitterionic intermediate betaine.
Than the extra electron on oxygen atom attack on
electrodeficient phosphorous atom to form a four-membered
cyclic intermediate, an oxaphosphetane.
The four membered ring clave (due to ring strain) to
form stable alkene and stable tri phenyl phosphene.
of water molecule convert in to imine function group. In sub-
sequent steps by loosing of two mole water and nitrogen mol-
ecule via carbanion intermediate it will generate alkane.
24. Wittig Reaction
It is a reaction of an aldehyde or ketone with a triphenyl
phosphonium ylide (often called a Wittig reagent) to give an
alkene and triphenylphosphine oxide (Ph3
PO). The reaction
also known as Wittig Olefination.
Wittig reactions are most commonly used to couple
aldehydes and ketones to singly substituted phosphine
ylides. With simple ylides this results in almost exclusively
the Z-alkene product.
Ylides: It may be defined as the group 15 and 16 of periodic
table having positive charge directly attached to carbon con-
taining negative charge (extra unshared pair of electron) due
to pY-dY bonding is known as ylides.
+ +
P+
C−
O
R2
R1
R3
C C
R2
R1
R4
R3
C
Aldehyde/
Ketone
Phosphorous
Ylide
Alkene Triphenyl
Phosphene
O
Ph3P
Ph3
R4
R1
R1
R1
R1
H
H
H
H
H
H
Betain Like
Intermediate
H
O
1 2
7 6 5
3 4
O
R2
R2
R2
R2
PH3P
PH3P PH3P
+ Ph3PO
+ −
−
O
−
+
+
R1
H
H
R2
PH3P
O
25. Wurtz Reaction
In this reaction, two alkyl halide molecules are coupled
in presence of sodium metal (Na) in anhydrous ether or
Tetrahydrofuran to form a new carbon carbon bond and thus
by giving a symmetrical alkane. The Wurtz reaction must
be performed under anhydrous conditions because the alkyl
free radical formed.
R–X + 2Na + R–X
Dry Ether
R–R + 2NaX
Reaction Mechanism
R X + 2Na R−
Na+
+ NaX
R−
Na+
+ R R + NaX
R X
f water molecule convert in to imine function group. In sub-
sequent steps by loosing of two mole water and nitrogen mol-
ecule via carbanion intermediate it will generate alkane.