ALDEHYDES AND KETONES
1
By:
Dr. Siham Lahsasni
ALDEHYDES: STRUCTURE AND NOMENCLATURE
 General
formula: RCHO or RCH=O
 The aldehyde group is always at the end of a
chain
 IUPAC system: Select the longest continuous
carbon chain that contains the C=O group
and replace the ending by the suffix al.
 The CHO group is assigned the number 1
position and takes precedence over other
functional groups that may the present such
2
as –OH, C=C for example.
O
H
C
H
H3C
Common Formaldehyde
IUPAC
Methanal
O
Cl
H3C
CH
H3C CH2
H
Acetaldehyde
HO
H
H3CH2CH2C
Propanal
O
C
H
C
O
Propionaldehyde
Ethanal
C
Butyraldehyde
Butanal
O
H
H3CHC=HC
3-Hydroxypropanal
2-Chloropropanal

O
O
C
H
2-Butenal
Aromatic aldehydes are usually designated as derivatives of
the simplest aromatic aldehyde, Benzaldehyde.
O
O
H
H
OH
H
H
O 2N
Benzaldehyde
O
O
p-Nitrobenzaldehyde o-Hydroxybenzaldehyde
Salicylaldehyde
H3CO
p-Methoxybenzaldehyde
3
Anisaldehyde
H
KETONES: STRUCTURE AND NOMENCLATURE
General formula: RCOR’ (R and R’=alkyl or aryl)
 Common name: listing the alkyl substitutents attached to the
carbonyl group, followed by the word ketone.
 IUPAC system: relpace the ending –e by the suffix –one. The
chain is numbred in such a way as give the lowest number to
the C=O group.

O
H3C
C
O
CH3
Common Dimethyl ketone
IUPAC
H3C
C
O
C6 H 5
Methyl phenyl ketone
Acetone
Acetophenone
Propanone
Phenyl ethanone
H3C
C
O
CH=CH 2 H5C6
Methyl vinyl ketone
C
C6H5
Diphenyl ketone
Benzophenone
3-Buten-2-one
Diphenylmethanone
4
O
O
C2 H 5
O
OH
CHO
C
C2 H 5
Cyclopentylpropanone 3-Ethyl-2-hydroxycyclohexanone
5-Oxohexanal
5
PHYSICAL PROPERTIES OF KETONES
AND ALDEHYDE




O
C
+
O
C
O
C
-
C
O



Because the polarity of the carbonyl group, aldehydes and
ketones are polar compounds.
 Dipole-dipole attractions, although important, are not as
strong as intractions due to hydrogen bonding. As a result,
the boiling points of aldehydes and ketones are higher than
those of nonpolar alkanes, but lower than those of alcohols.


C


O


H
O


H


O
C
The lower aldehydes and ketones are soluble.
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PREPARATION OF ALDEHYDES AND KETONES
1- Oxidation of alcohols
RCH 2
OH
O
CrO 3/ pyridine
R
Cu / heat
H
O
CrO 3/ pyridine
R2CH
R
OH
C
R
Cu / heat
2- Ozonolysis of alkenes
A
A
A
A
1)O 3
A
2)Zn / H 2O
O
A
+
A
O
A
3- Hydration of alkynes
H
C
C
+
HO H
H2SO4, HgSO4
H
C
C
OH
an enol unstable
C
C
H
O
carbonyl more stable
7
4- Friedel Grafts acylation
O
O
+
AlCl 3
R
CH3
Cl
8
REACTIONS OF ALDEHYDES AND KETONES
1- Reduction of carbonyl group
2 H 2 / Pd
H3C
OH
H3C
O
H
1) NaBH 4
H3C
OH
2) H 2O
9
2- Addition of Grignard Reagents: Formation of alcohols
R
R'
O
R
+
C
R'MgX
H
1) Dry ether
R
HO
+
C
OH
2) H 2O
O
H3C
CH
C2H5MgX
H
1) Dry ether
2) H 2O
H3C
CH
C2H5
R'
O
C
R'
+
R''MgX
1) Dry ether
2) H 2O
R
C
OH
R''
CH3
O
+
CH 3MgX
1) Dry ether
2) H 2O
OH
10
3- Oxidation reaction
aR-CHO or
Ar-CHO
KMnO4
or
RCOOH
or K Cr O
2 2 7
ArCOOH
b- Iodoform reaction: The reaction occurs in any aldehyde or
ketone containing CH3CO.
O
H3C
C O
+
3 I2
+
4 NaOH
R
O Na
R
CH3
H3C
I2 / NaOH
-
H3C
COONa
+
+ CHI3 +
+
3 NaI
CHI3
O
11
4- Addition of Hydrogen Cyanide: Formation of cynohydrins
R'
O
R
C
+
R'
R
HCN
C
OH
CN
Cyanohydrin
CN
O
H
NH2
OH
+
OH
H2 / Pt
+
or LiAlH 4 and H 3O
HCN
Benzaldehyde cyanohydrin
O
OH
+
H3O
CN
HCN
OH
+
COOH
Heat
5- Addition of acetylide ions:
R'
O
R
C
R'
+
-
2
C Na
R C
H3 O
+
+
R
C
C
C
R
2
OH
O
+ H3C
C
-
C Na
+
H3O
+
OH
C
12
C
CH3
6- Addition of alcohols:
R'O
O
C
R
R'O
+
+
2
R'OH
H
R''OH
C
R
OH
2
R
Hemiacetal
2
Ketone
Hemiketal
R =H:
R =Alkyl
O
H3C
+
C2H5OH
H3C
C
H 5C 2O
CH
OC 2H5
CH3
C2H5OH
C2H5OH
+
H
H3C
C
OC 2H5
H5C2O
H
H3C
CH
Acetal
HO
+
+
2
Ketal
Hemiacetal
H3C
OR''
R
Acetal
H
H
O
C
HO
+
C
H
2
R
Aldehyde
R
+
OC 2H5
CH3
Hemiketal
C2H5OH
+
H
H3C
C
OC 2H5
CH3
Ketal
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7- Addition of Ammonia and Ammonia Derivatives
NH3
C NH
Imine
C O
NH 2OH
Hydroxylamine
H2N
C N OH
Oxime
NH2
Hydrazine
C N
NH2
Hydrazone
14