King Saud University
Chemistry Department
ALDEHYDES AND KETONES
145 Chem
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King Saud University
Chemistry Department
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
as –OH, C=C for example.
145 Chem
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King Saud University
Chemistry Department
O
O
O
O
H
H3C
H
H
H
H3CH2CH2C
H3CH2C
Common Formaldehyde Acetaldehyde Propionaldehyde Butyraldehyde
IUPAC
Methanal
Ethanal
Propanal
O
H3C CH
H
Cl
IUPAC
2-ChloroPropanal
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Butanal
O
H2
C C
HO
C
H2
H2
3-HydroxyPropanal
H
O
H
H
C C
H3C
H
H
2-Butenal
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King Saud University
Chemistry Department
•
Aromatic aldehydes are usually designated as derivatives of the simplest aromatic
aldehyde, Benzaldehyde.
O
O
H
H
O 2N
p-Nitrobenzaldehyde
O
Benzaldehyde
OH O
H
o-Hydroxybenzaldehyde
Salicylaldehyde
145 Chem
H
H3CO
P-Methoxybenzaldehyde
Anisaldehyde
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King Saud University
Chemistry Department
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.
145 Chem
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King Saud University
Chemistry Department
O
H3C
Common
C
O
CH3
H3C
O
C
C6 H 5
H3C
C
CH=CH 2 H5C6
C
C6H5
Dimethyl Ketone
Methyl phenyl ketone
Methyl vinyl
Diphenyl ketone
Acetone
Acetophenone
ketone
Benzophenone
Propanone
Phenyl ethanone
3-Buten-2-one
Diphenylmethanone
IUPAC
O
O
C2 H 5
O
O
OH
CHO
C
C2 H 5
1-Cyclopentylpropanone 3-Ethyl-2-hydroxycyclohexanone
145 Chem
5-Oxohexanal
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King Saud University
Chemistry Department
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.
• The lower aldehydes and ketones are soluble in water.

C
145 Chem

O


H
O


H


O
C
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King Saud University
Chemistry Department
PREPARATION OF ALDEHYDES AND KETONES
1- Oxidation of alcohols
RCH2OH
O
CrO3/pyridine
or Cu/ heat
R
H
O
R2CHOH
CrO3/pyridine
or Cu/ heat
R
R
2- Ozonolysis of alkenes
A
A
145 Chem
A
A
1] O3
2]Zn/ H2O
A
O
A
+
A
O
A
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King Saud University
Chemistry Department
PREPARATION OF ALDEHYDES AND KETONES
3- Hydration of alkynes
C C
+
HO H
H2SO4,HgSO4
H
H
C
C
OH
an enol unstable
4- Friedel Grafts acylation
H O
carbonyl more stable
O
O
+
145 Chem
AlCl3
Cl
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King Saud University
Chemistry Department
REACTIONS OF ALDEHYDES AND KETONES
Nucleophilic addition Reactions
1- Reduction of carbonyl group
2H2/Pd
H3C
OH
H3C
OH
H
H3C
O
1] NaBH4
2]H2O
145 Chem
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King Saud University
Chemistry Department
2- Addition of Grignard Reagents: Formation of alcohols
O
+
R
H
R'MgX
O
H3C
2] H3O+
R
+ C2H5MgX
H
2] H3O+
H3C
CH
R'
R''MgX
2] H3O+
R'
C2H5
OH
1] dry ether
+
CH
OH
1] dry ether
O
R
OH
1] dry ether
R
C
R''
R'
CH3
O
1] dry ether
+
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CH3MgX
2] H3O
+
OH
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King Saud University
Chemistry Department
3- Oxidation reaction
O
O
or
R
Ar
H
H
O
O
KMnO4
or
or K2Cr2O7
R
OH
Ar
OH
4- Addition of Hydrogen Cyanide: Formation of cynohydrins
O
R
OH
+ HCN
R'
R
R'
cyanohydrin
CN
O
CN
H
O
OH
+
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OH
Benzaldehyde cyanohydrin
+ HCN
HCN
CN
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King Saud University
Chemistry Department
6- Addition of alcohols:
O
C2H5OH,H+
H3C
OH
H3C
H
Ph
CH3
145 Chem
C2H5OH,H
H3C
OH
Ph
OC2H5
H
Hemiacetal
C2H5OH,H+
Ketone
OC2H5
H
Aldehyde
O
OC2H5
+
Acetal
OC2H5
+
OC2H5
C2H5OH,H
Ph
OC2H5
CH3
CH3
Hemi ketal
Ketal
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King Saud University
Chemistry Department
7- Addition of Ammonia and Ammonia Derivatives
N NH2
NH2NH2
-H2O
H3C
H
hydrazone
N NHPh
PhNHNH2
O
H3C
H3 C
H
phenyl hydrazone
H
H
N N OH
Aldehyde
NH2OH
H
Oxime
H
imine
H3C
NH
NH3
H3C
145 Chem
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King Saud University
Chemistry Department
Question
1- The correct name of the following compound
is:
A) 3-hydroxyhexanal
B) 3-hydroxy-4-hexenal
C) 4-hydroxy-5-hexenal
D)3-hydroxy-1-hexenal
2- The structure of Acetal is:
O
A)
C2H5
B)
OH
C)
C2H5
145 Chem
O
OH
O
C2H5
OH
O
C H
H 2 5
O
D)
C2H5
C2H5
O
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King Saud University
Chemistry Department
3- Reaction of phenyhydrazine with carbonyl compounds
(aldyhydes or ketones) gives:
A) Oxime
B) Phenylhydrazone
C) ImineD) Hemiacetal
4 - Which of the following compounds has the highest boiling point?
145 Chem
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King Saud University
Chemistry Department
Thank you for your attention
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