LECTURE № 7
THEME: Aldehydes and
ketones of the aliphatic row.
Aldehydes and ketones of
the aromatic row.
associate. prof. Ye. B. Dmukhalska, assistant. I.I. Medvid
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Plane
Structure of aldehydes and ketones.
Nomenclature of aldehydes
Nomenclature for ketones.
Physical properties of aldehydes and ketones
Methods of aldehydes and ketones obtaining.
Chemical properties of aldehydes and ketones
Unsaturated aldehydes and ketones.
Chemical properties of unsaturated aldehydes and ketones.
Dialdehydes and diketones.
Nomenclature of aromatic aldehydes and ketones.
Methods of obtaining of aromatic aldehydes and ketones.
Chemical properties of aromatic aldehydes and ketones.
Some representatives of aromatic aldehydes and ketones.
Aldehyde - а carbonyl compound containing two
hydrogen atoms or hydrogen and alkyl group.
Example:
Acetaldehyde
Phenylethanal
Propionaldehyde
Butyraldehyde
Benzaldehyde
Structure of aldehydes and ketones.
When two alkyl groups are attached to the carbonyl, the
compound is а ketone.
When two hydrogen atoms, or one hydrogen and one alkyl
group are attached to the carbonyl, the compound is an
aldehyde.
Lewis structure
R, R’ = Н or alkyl
Kekule structure
Condensed structure
Ketone - а carbonyl compound containing а pair of
cumulative double bonds, one of which is the
carbonyl group, or ketone is а carbonyl compound
containing two alkyl groups.
Example:
5–methylhexan-3-one
1-phenylethanone
diphenylmethanone

The structure of formaldehyde, the simplest member
of the class, is depicted below, along with its
experimental bond lengths and bond angles.
Bond lengths
Bond angles
С=O
1.203
Н—С—O
121.8

С—Н
1.101
Н—С—Н
116.6
The actual structure is а composite of the normal octet
structure, СН2 =О and the polarized structure +СН2 - O¯,
which corresponds to а carbonium oxide. The composite
structure may be represented with dotted line symbоlism
which shows the partial charges in carbon and oxygen and
the partial single bond character of the C –O bond.
One physical consequence of this bond polarity is
that carbonyl compounds generally have rather high
dipole moments. The experimental dipole moments
of formaldehyde and acetone are 2.27 D and 2.85
D, respectively.
The chemical consequences of this bond polarity will be are
become apparent during our discussions of the reactions of
carbonyl groups. We shall find that the positive carbon can
react with bases and that much of the chemistry оf the
carbonyl function corresponds to that of а relatively stable
carbonium ion.
The ione pair electrons in the carbonyl oxygen have weakly
basic properties. In acidic solution, acetone acts as а Lewis
base and is protonated to а small but significant extent.
In fact, acetone is а much weaker Lewis base than is
water. The material is one half protonated only in
82% sulfuric acid. This corresponds to an
approximate pKa for the conjugate acid of acetone of
- 7.2 (the approximate рKa of НО+ is - 1.7).
Nomenclature of aldehydes

The longest continuous chain that contains the
group
provides the base name for aldehydes. The -e ending of the
corresponding alkane name is replaced by -al, and substituents
are specified in the usual way. It is not necessary to specify the
location of the
group in the name, since the chain must be
numbered by starting with this group as C-1. The suffix -dial is
added to the appropriate alkane name when the compound
contains two aldehyde functions.
4,4-Dimethylpentanal
5-Hexenal
2-Phenylpropanedial
When a formyl group (-CH=O) is attached to a ring, the ring
name is followed by the suffix -carbaldehyde.
Cyclopentanecarbaldehyde
2-Naphthalenecarbaldehyde
Certain common names of familiar aldehydes are acceptable
as IUPAC names. A few examples include
Formaldehyde
(methanal)
Acetaldehyde
(ethanal)
Benzaldehyde
(benzenecarbaldehyde)
The IUPAC rules for naming aldehydes are as follows:
1. Select as the parent carbon chain the longest chain
that includes the carbon atom of the carbonyl group.
2. Name the parent chain by changing the -е ending of
the corresponding alkane name to -al.
3. Number the parent chain by assigning the number 1
to the carbonyl carbon atom of the aldehyde group.
4. Determine the identity and location of any
substituents, and append this information to the front
of the parent chain name.
propanal
5-methylhexanal
Nomenclature of ketones.
With ketones, the -e ending of an alkane is replaced by -one in
the longest continuous chain containing the carbonyl group.
The chain is numbered in the direction that provides the lower
number for this group.
3-Hexanone
4-Methyl-2-pentanone
4-Methylcyclohexanone
Although substitutive names of the type just described are
preferred, the IUPAC rules also permit ketones to be named by
functional class nomenclature. The groups attached to the
carbonyl group are named as separate words followed by the
word “ketone.” The groups are listed alphabetically.
Ethyl propyl
ketone
Benzyl ethyl ketone
Divinyl ketone
A few of the common names acceptable for ketones
in the IUPAC system are
(The suffix -phenone indicates that the acyl group is attached
to a benzene ring.)
Methods of obtaining of aldehydes and ketones.
1. Ozonolysis of alkenes. This cleavage reaction is more often
seen in structural analysis than in synthesis. The substitution
pattern around a double bond is revealed by identifying the
carbonyl-containing compounds that make up the product.
Hydrolysis of the ozonide intermediate in the presence of zinc
(reductive workup) permits aldehyde products to be isolated
without further oxidation.
2. Hydration of alkynes (Kucherov reaction). Reaction
occurs by way of an enol intermediate formed by
Markovnikov addition of water to the triple bond.
3. Friedel-Crafts acylation of aromatic compounds. Acyl
chlorides and carboxylic acid anhydrides acylate aromatic rings in the
presence of aluminum chloride. The reaction is electrophilic aromatic
substitution in which acylium ions are generated and attack the ring.
4. Oxidation of primary alcohols to aldehydes. Pyridinium
dichromate (PDC) or pyridinium chlorochromate (PCC) in anhydrous
media such as dichloromethane oxidizes primary alcohols to aldehydes
while avoiding overoxidation to carboxylic acids.
5. Oxidation of secondary alcohols to ketones. Many oxidizing
agents are available for converting secondary alcohols to ketones. PDC
or PCC may be used, as well as other Cr(VI)-based agents such as
chromic acid or potassium dichromate and sulfuric acid.
6. Hydrolysis of heminals dyhalohenderivaties. During
hydrolysis of hem-dihalohenalkanes with atoms of halogen at
primary atom of carbon formed aldehydes, while the
secondary – ketones:
7. Pyrolysis salts of carboxylic acids : salt mixture of formic acid
and other acid – aldehyde.
Salts of other acids – ketones.
O
CH3 - C _=
O_
_ Ca
_O
H - C=
O
t
O
=
_
CH3 - C
H
CH3 - CH2 - C - CH3 + CaCO3
=
O
=
_
CH3 - CH2 - C
O_
_ Ca
_O
CH3 - C=
O
300 C
O
+ CaCO3
 8.
Oxosynthesis. Interaction of alkenes
with carbone (II) oxide, at the higher
temperature, pressure and presence of
catalyst.
6. Chemical properties of aldehydes and ketones
The reactions of aldehydes and ketones can be
divided into the following types:
Keto – enol equilibrium. Aldehydes and ketones exist in
solution as an equilibrium mixture of two isomeric forms, the
keto form and the enol (from -ene + -ol, unsaturated alcohol)
form. For simple aliphatic ketones, there is very little of the
enol form present at equilibrium, as shown by the following
examples.
1. Reactions of reduction and oxidation
1). Reduction to hydrocarbons. Two methods for converting
carbonyl groups to methylene units are the Clemmensen
reduction (zinc amalgam and concentrated hydrochloric acid)
and the Wolff–Kishner reduction (heat with hydrazine and
potassium hydroxide in a highboiling alcohol).
2). Reduction to alcohols . Aldehydes are reduced to primary
alcohols, and ketones are reduced to secondary alcohols by a
variety of reducing agents. Catalytic hydrogenation over a metal
catalyst and reduction with sodium borohydride or lithium
aluminum hydride are general methods.
3). Reactions of aldehyde oxidation
Tollens’ reagent – “silver mirror”
reaction.
 With
With Fehling reagent: after heating red
precipitate of copper (I) oxide formed.
Reaction of “silver mirror” and reaction with
Fehling reagent used for identification of
aldehyde group.
Aldehydes are readily oxidized to carboxylic acids by a
number of reagents, including those based on Cr(VI)
in aqueous media.
4). Oxidation of ketones
 Only
in the presence of strong oxidant
(potassium permanganate or bichromate). As
a result mixture of acids formed.
2. Reactions of nucleophilic addition (AN)
1). Addition of Grinjar’s reagents and organolithium
compounds . Products of additions be carbonyl group
formed which hydrolyzed at the presence of diluted
mineral acids to alcohols.
2). Cyanohydrine (α-hydroxinitrile) formation. Reaction is
catalyzed by cyanide-ion. Cyanohydrins are useful synthetic
intermediates;cyano-group can be hydrolyzed to -CO2H or
reduced to -CH2NH2.
Reaction goes at the presence of base
4). Hydratation. Aldehydes form hydrates at the dissolution
in water. Hydrates are not stable in water
5). Acetal formation. Reaction is acid-catalyzed. Equilibrium
constant normally favorable for aldehydes, unfavorable for
ketones. Cyclic acetals from vicinal diols form readily.
 6)
Reaction with sodium hydrosulfite.
Aldehydes give this reaction and ketones with CH3-COgroup.
3. Accession- elimination reactions
1). Reaction with primary amines. Isolated products are imines (Schiff’s
base). A carbinolamine intermediate is formed, which undergoes
dehydrates to imine.
2). Reaction with secondary amines. Isolated product is an enamine.
Carbinolamine intermediate cannot dehydrates to a stable imine.
3). The Wittig reaction. Reaction of a phosphorus ylide with
aldehydes and ketones leads to the formation of an alkene. A
versatile method for the preparation of alkenes.
 4)
Interaction with ammonium.
Aldehydes with ammonium give aldimines
5) Interaction with hydroxylamine –
aldehydes give aldoxymes, ketones –
ketoxymes.
 6)
Interaction with hydrazine and its
derivatives
4. Reactions of condensation
1). Aldol condensation
As noted earlier, an aldehyde is partially converted to its enolate anion by
bases such as hydroxide ion and alkoxide ions. This type of
condensations is character for aldehydes which have hydrogen atoms at
the α-carbon atom.
In a solution that contains both an aldehyde and its enolate
ion, the enolate undergoes nucleophilic addition to the
carbonyl group.
Product of aldol addition at the heating eliminates
water and form α, β-unsaturated aldehydes (crotone
condensation) :
The alkoxide formed in the nucleophilic addition step then
abstracts a proton from the solvent (usually water or ethanol)
to yield the product of aldol addition. This product is known
as an aldol because it contains both an aldehyde function and
a hydroxyl group (ald+ol=aldol). An important feature of aldol
addition is that carbon–carbon bond formation occurs between
the -carbon atom of one aldehyde and the carbonyl group of
another. This is because carbanion (enolate) generation can
involve proton abstraction only from the α-carbon atom.
Ketones also give aldol condensation but at
the more hard conditions
In a strong acidic medium ketones give crotone
condensation with formation of unsaturated ketones.
2). Condensation by Tishchenko
The Tishchenko reaction is a disproportionation reaction that
allows the preparation of esters from two equivalents of an
aldehyde.
 Mechanism
of the Tishchenko
condensation:
5. Reactions by the α-carbone atom
Halogenation. Iodoformic test.
O
=
CH3 - C _
+ J2 + NaOH
CH3
O NaOH
=
CH3 - C _
CJ3
O
=
CH3 - C _
+ CHJ2
ONa
 6.
Reactions of polymerization.
In the presence of sulfate acid.
7. Unsaturated aldehydes and ketones.
The carbonyl group withdraws electron density from
the double bond, and both the carbonyl carbon and
the carbon are positively polarized. Their greater
degree of charge separation makes the dipole
moments of ,-unsaturated carbonyl compounds
significantly larger than those of comparable
aldehydes and ketones.
α,β-Unsaturated carbonyl compounds contain
two electrophilic sites: the carbonyl carbon and
the carbon atom that is β to it. Nucleophiles
such as organolithium and Grignard reagents
and lithium aluminum hydride tend to react by
nucleophilic addition to the carbonyl group, as
shown in the following example:
8. Chemical properties of unsaturated aldehydes and
ketones.
1). Conjugate accession to α,β-unsaturated carbonyl
compounds . The β-carbon atom of an α,β-unsaturated
carbonyl compound is electrophilic; nucleophiles, especially
weakly basic ones, yield the products of conjugate addition to
α,β- unsaturated aldehydes and ketones.
2). With cyanic acid – cyanehydrines
form
3). Crotone condensation
4). Robinson annulation. A combination of conjugate addition of an enolate
anion to an α,β- unsaturated ketone with subsequent intramolecular aldol
condensation.
5). Conjugate addition of organocopper compounds. The principal
synthetic application of lithium dialkylcuprate reagents is their reaction
with α,β- unsaturated carbonyl compounds. Alkylation of the β-carbon
occurs.
Dialdehydes and diketones
Dialdehydes to include compounds that contain two
aldehydic groups, to diketones - two keto groups. The
simplest representative dialdehydes is glyoxal or ethandial
and diketones - diacetyl or butandion.
O
Glyoxal is an organic compound with the formula
C
C
OCHCHO. This yellow colored liquid is the
H
H
smallest dialdehyde (two aldehyde groups).
Commercial glyoxal is prepared either by the gas phase oxidation of
ethylene glycol in the presence of a silver or copper catalyst or by the
liquid phase oxidation of acetaldehyde with nitric acid.
O
Diacetyl (IUPAC systematic name:
CH3
butanedione or 2,3-butanedione) is a
O O
natural byproduct of fermentation. It is a
vicinal diketone (two C=O groups, side-by-side) with the
molecular formula C4H6O2. Diacetyl occurs naturally in
alcoholic beverages and is added to some foods to impart a
buttery flavor.
CH3
C
C
Kaniccarro reaction – intermolecular
oxidation reduction.
 1)
2) Interaction with hydroxylamine
Nomenclature of aromatic aldehydes
and ketones



Aromatic aldehydes and ketones divided on two groups:
1). Aldehydes which have aldehyde group in benzene
ring; β
2). Aldehydes which have aldehyde group in side chaine.
 Aromatic
ketones divided on two groups:
 1) truly aromatic (carbonyl group connected
with two aromatic radicals);
 2) fatty aromatic (carbonyl group connected
with one aromatic and one alifatic radical.
Methods of obtaining
 1).
Oxidation of aromatic hydrocarbons.
2) Hattermane-Koch (formylation reaction).
 3).
Fridel-Krafts reaction (acylation).
Chemical properties
1). Interaction with ammonium (in the ratio of
3:2).
2). Kaniccarro reaction. In the presence of strong base
or concentrated alkali solution ( reaction of
disproportionation).
Mechanism of reaction:
3). Reactions of condensation.
 In
the presence of bases aromatic aldehydes
gives condensations with aldehydes, ketones,
anhydrides of carboxylic acids.
 Perkin's
condensation:
Mechanism:
Benzoic condensation

Condensation of two molecules of aldehydes in the
presence of cyanic acids salts with formation of
aromatic α-oxiketones (benzoines).
Mechanism of benzoic condensation:
4). Halogenation.
5). Electrophilic substitution
Some representatives of
aromatic aldehydes and
ketones
1). Benzophenone – C6H5-CO-C6H5.
Obtaining:
 2).
Quinones
Obtaining:
Thank you for attention!