Transcript 4.9 Oxidation and reduction of Aldehydes and ketones

4.9 Oxidation and reduction of
Aldehydes and ketones
=>
Tollens Test


Add ammonia solution to AgNO3 solution until
precipitate dissolves.
Aldehyde reaction forms a silver mirror.
O
R C H + 2
+
NH3)2
_
+
3 OH
+
Ag(NH3)2
_
+
3 OH
O
H2O
O
H2O
2 Ag + R C O
2 Ag + R C O
_
+
_
+
4 NH3 + 2 H2O
=>
4
Oxidation of ketones
Ketones  no reaction
Reduction –
Catalytic Hydrogenation
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
Ketones give secondary alcohols
Aldehydes give primary alcohols
O
CH3CHO
OH
H2 / Ni
H2 / Ni
H
CH3CH2OH
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
Reduction: aldehyde + hydrogen --> pri. Alcohol
Form of addition reaction.
H3C
H2
C
C
H
O + H2
Reduction: aldehyde + hydrogen

Break hydrogen bond
H
H
H3C
H2
C
C
H
H
H
O + H2
Reduction: aldehyde + hydrogen

Break double bond and use electrons to bond with hydrogen.
H
H3C
H2
C
C
H
H
O
H2 H
O
C
H3C
C
H
H
Reduction: aldehyde + hydrogen

Brief Method
H3C
H2
C
O
C
H
+ H
H
H2 H
O H
C
H3C
C
H
4.10 Addition of Alcohol

Hemiacetal and Acetal Functional Groups