LECTURE 2
THEME: Structure and chemical
properties of carboxylic acids.
Heterofunctional compounds.
Lecturer: Yevheniya. B. Dmukhalska
1.
2.
3.
4.
5.
6.
7.
8.
Plan
Nomenclature of carboxylic acids
Physical properties of carboxylic acids.
Classification of carboxylic acids
Methods of preparation of carboxylic acids
Chemical properties of carboxylic acids.
Heterofunctional compounds.
Hydroxy-acids, nomenclature, isomerism,
chemical properties and specific reactions for
hydroxy-acids.
Introduction of optical isomerous. Mirror
(optical) isomerism. Asymmetric carbon atom.
Properties of enantiomers.
Carboxylic acids
Carboxylic acids are compounds whose
characteristic functional group is the carboxyl
group - COOH , example:
Common
formula of carboxylic acid:
Nomenclature of carboxylic acids
Nowhere in organic chemistry are common
names used more often than with the
carboxylic acids. Systematic names for
carboxylic acids are derived by counting the
number of carbons in the longest continuous
chain that includes the carboxyl group and
replacing the -e ending of the corresponding
alkane by -oic acid.
Table 1. Systematic and common names of some carboxylic acids
Classification of carboxylic acids :
1. From the nature of hydrocarbon radical:
a) saturated acid is acid, which has only simple bonds
in molecule. Example: formic acid, buthanic acid;
b) unsaturated acid is an acid, which has both as
simple bonds and duble bonds in molecule.
Example: oleic acid, linoleic acid, linolenic acid,
arashdonic acid;
c) aromacic acid is acid, which contain aromatic ring.
Example: benzoic acid.
2. The number of carboxyl groups
a) monocarboxylic acid is acid, which has one
carboxylic group in molecule. Example: acetic
acid, formic acid, buthanic acid;
b) dicarboxylic acid is acid, which has two carboxylic
group in molecule. Example: oxalic acid, malonic
acid.
The names of some saturated monocarboxylic acids
Structural formula
Name of nomenclature
O
H
C
trivial
substitute
rational
formic acid
methanoic acid
-
acetic acid
etanoic acid
acetic acid
propionic
acid
propanoic acid
methylacetic acid
oil acid
butanoic acid
ethylacetic acid
iso oil acid
2-methylpropanoic
acid
dimethylacetic acid
valeric acid
pentanoic acid
propylacetic acid
iso valeric
acid
3-methylbutanoic
acid
methylethylacetic
acid
OH
O
H3C
C
OH
O
H3C CH2
C
OH
O
H3C CH2
3
CH2
C
2
1
C
H3C CH
OH
O
OH
CH3
O
H3C CH2
4 3
H3C CH
2
CH2
CH2
1
C
CH3
CH2
O
OH
C
OH
CH3-(CH2)4-COOH
capronic acid hexanoic acid
CH3-(CH2)10-COOH
lauric acid
dodecanoic acid
CH3-(CH2)12-COOH
myristic acid
tetradecanoic acid
CH3-(CH2)14-COOH
palmitic acid
hexadecanoic acid
CH3-(CH2)16-COOH
stearic acid
octadecanoic acid
n-butylacetic acid
The names of some unsaturated monocarboxylic acids
Name of nomenclature
Structural formula
trivial
CH2=CH-COOH
CH2
C
COOH
substitute
acrylic acid
propenoic acid
methacrylic acid
2-methylpropenoic acid
vinyl acetic acid
3-butenoic acid
crotonic acid
trans-2-butenoic acid
iso crotonic acid
cus-2-butenoic acid
propiolic acid
propionoic acid
tetrolic acid
2-butynoic acid
oleic acid
cus-9-octadecenoic acid
Linoleic acid
cus-9-cus-12octadecadienoic acid
linolenic acid
cus-9-cus-15octadecatrienoic acid
CH 3
CH2=CH-CH2-COOH
H
COOH
C
C
H
CH3
H
H
C
CH3
CH
C
4
3
2
CH3
C
C
COOH
COOH
CH3
CH (CH2)7
COOH
CH
CH2
CH (CH2)7
COOH
1
CH (CH2)7
CH3 (CH2)4
C
CH
CH
COOH
CH
CH2
CH CH2
CH3
CH
CH CH2 CH
CH (CH2)7
COOH
The names of some dicarboxylic acids
Structural formula
Name of nomenclature
trivial
substitute
HOOC-COOH
oxalic acid
ethandioic acid
HOOC-CH2-COOH
malonic acid
propandioic acid
HOOC-CH2-CH2-COOH
succinic acid
butandioic acid
HOOC-CH2-CH2-CH2-COOH
glutaric acid
pentandioic acid
HOOC-CH2-CH2-CH2-CH2-COOH
adypinic acid
hexandioic acid
HOOC-(CH2)5-COOH
pimelic acid
heptadioic acid
HOOC-(CH2)6-COOH
cork acid
octandioic acid
maleic acid
cus-butendioic acid
fumaric acid
trans-butendioic acid
phthalic acid
1,2-benzoldicarbonic acid
iso phthalic acid
1,3-benzoldicarbonic acid
H
H
C
C
COOH
HOOC
H
COOH
C
HOOC
C
H
COOH
COOH
COOH
COOH
Physical properties of carboxylic acids.
The melting points and boiling points of carboxylic acids are
higher than those of hydrocarbons and oxygen-containing
organic compounds of comparable size and shape and indicate
strong intermolecular attractive forces.
The hydroxyl group of one carboxylic acid molecule acts as a
proton donor toward the carbonyl oxygen of a second. In a
reciprocal fashion, the hydroxyl proton of the second carboxyl
function interacts with the carbonyl oxygen of the first.
Methods of preparation of carboxylic acids.
1. Oxidation of alkylbenzenes.
2. Oxidation of primary alcohols. Potassium
permanganate, potassium chromate and chromic
acid convert primary alcohols to carboxylic acids by
way of the corresponding aldehyde.
3. Oxidation of aldehydes. Aldehydes are
particularly sensitive to oxidation and are converted to
carboxylic acids by a number of oxidizing agents,
including potassium permanganate and chromic acid.
4. Synthesis of carboxylic acids by the preparation and
hydrolysis of nitriles.
Once the cyano group has been introduced, the nitrile is subjected
to hydrolysis. Usually this is carried out in aqueous acid at
reflux.
Chemical properties of carboxylic acids.
Formation of acyl chlorides. Thionyl chloride reacts
with carboxylic acids to yield acyl chlorides.
 Formation
of acyl chlorides. Reaction with
halo-compounds:
Reduction reaction.
Carboxylic acids are reduced to primary alcohols by the
powerful reducing agent lithium aluminum hydride.
Acidity:

Iontzation:
 Reactions
involving the ОН-bond
a)
b)
Reactions involving the ОН-bond
Important reaction of carboxylic acids involving the ОН
bond - the reaction with bases to give salts.
Another important reaction involving this bond is the
reaction of carboxylic acids with diazomethane. The
products of this reaction are the methyl ester and
nitrogen.
ESTERIFICATION
 This
page looks at esterification - mainly the
reaction between alcohols and carboxylic acids
to make esters.
α-halogenation of carboxylic acids
The enol content of a carboxylic acid is far less than that of an aldehyde or
ketone, and introduction of a halogen substituent at the -carbon atom
requires a different set of reaction conditions. Bromination is the reaction
that is normally carried out, and the usual procedure involves treatment of
the carboxylic acid with bromine in the presence of a small amount of
phosphorus trichloride as a catalyst.

This method of α bromination of carboxylic acids is called the
Hell–Volhard– Zelinsky reaction.
Decarboxylation of carboxylic acids.
The loss of a molecule of carbon dioxide from a carboxylic acid is
known as decarboxylation.
The formation amides. The most common reaction of this type is the reaction of
carboxylic acids with ammonia or amines to give amides. When ammonia is bubbled
through butyric acid at 1850, butyramide is obtained in 85% yield. The reaction
involves two stages. At room temperature, or even below, butyric acid reacts with the
weak base ammonia to give the salt ammonium butyrate. This salt is perfectly stable
at normal temperatures. However, pyrolysis of the salt results in the elimination of
water and formation of the amide.
O
O
C
H2C
H2C
OH
OH
C
O
succinic acid
+
NH3
t
N H
O
sukcynimide
+
H2O

Reaction formation carboxylic acid anhydrides.
Acid anhydrides are the most reactive carboxylic acid
derivatives.
NaOH
+
C6H5COONa
H2O
O
C2H5OH; H+
C6H5
+
C
H2O
OC2H5
ethylbenzoath
O
PCl5
C6H5
+
C
HCl
+
POCl3
Cl
benzoilchloride
C6H5COOH
benzoic acid
O
C6H5
C
(CH3CO)2O; H+
O
C6H5
+
2 CH3
C
O
anhydride of benzoic acid
COOH
H2
HOOC CH2
CH2
COOH
succinic acid
HOOC CH CH COOH
Br2
HOH; H+
CH
HOOC CH CH2
malic acid
COOH
CH
Br Br
2, 3 -dibromsuccinic acid
HCl
HOOC CH CH2 COOH
chlorsuccinic acid
COOH
COOH
butendioic acid
[O]
HOOC
KMnO4
CH
CH COOH
racemic acid
8. Carboxylic acid derivatives.
These classes of compounds are classified as carboxylic acid
derivatives. All may be converted to carboxylic acids by hydrolysis.
Functional Group is any part of an organic compound, which is not а
carbon-hydrogen or carbon-carbon single bon.
There are mono-, poly- and heterofunctional group in the structure of
organic compounds:
Monofunctional group – contains only 1 functional group.
C2H5—OH
Polyfunctional group – contains several similar functional group.
H2C
CH
H2C
OH
OH
OH
Heterofunctional group – contains several different functional
group.
Sphingosine
Biological role:

Heterofunctional compounds are widespread in the
nature. They are in fruits and vegetable leafs. Also
they are formed in body. So, the lactic acid is
product of transformation glucose (glycolysis) in
human body. A malic and citric acid formed in a
cycle of tricarboxylic acids, which is also known as
citric acid cycle or Krebs' cycle. Hydroxo acids
such as: pyruvic acid, acetoacetic acid, oxaloacetic
acid, -ketoglutaric acid are important in
metabolism of carbohydrates.
Hydroxyacids
Hydroxyacids are the derivatives of carboxyl acids that
contain –OH group (1 or more).
β
3
H3C
α
2
1
CH
C
OH
O
OH
2-hydroxypropanoic acid
α-hydroxypropanoic acid
glycolic acid,
hydroxyacetic acid,
hydroxyethanoic acid
lactic acid,
α- hydroxypropanoic acid,
2- hydroxypropanoic acid
tartaric acid
α,α’-dihydroxysuccinic acid,
2,3-dihydroxybutandioic acid,
citric acid,
2-hydroxy-1,2,3-propantricarboxylic acid
malic acid,
hydroxysuccinic acid
hydroxybutanedioic acid
In a row of hydroxyacids often found the optical
isomery.
D-tartaric acid
L-tartaric acid
mezo-tartaric acid
Methods of preparation of hydroxyacids:
1.
Hydrolysis of α-halogenoacids
O
H3C
C
CH
O
+ NaOH
H2O
H3C
CH
OH
Cl
C
+ NaCl
OH
OH
lactic acid
2.
Oxidations of diols and hydroxyaldehydes
H3C
3.
CH
CH2
OH
OH
[O]
O
H3C
CH
[O]
C
O
H3C
H
OH
CH
OH
C
OH
Hydration of α,β-unsaturated carboxylic acids
O
CH2
CH
C
OH
O
+
+ H2O
H
H2C
OH
CH2
C
OH
β-hydroxypropanoic acid
4. Hydrolysis of hydroxynitriles (cyanohydrins)
Physical and chemical properties of
hydroxycarboxylic acid
For physical properties of hydroxycarboxylic acids are
colorless liquids or crystalline substance, soluble in water.
Chemical properties: in the molecule of hydroxyacids ether –
OH group or carboxyl group can react.
Carboxyl group can react forming:
a) salts:
O
H2C
CH2 C
+ NaOH
OH
O
H2C
CH2 C
ONa
OH
+ H2O
OH
sodium β-hydroxypropanoic acid
O
2 H2C
CH2 C
+ 2 Na
OH
OH
O
2 H2C
CH2 C
ONa
OH
+ H2
OH
O
H2C
CH2 C
O
O
2 H2C
CH2 C
Mg + H2O
+ MgO
O
OH
OH
H2C
CH2
C
O
OH
O
H2C
O
CH2 C
OH
+ NaHCO3
H2C
CH2 C
ONa
OH
+ H2CO3
OH
H2O
CO2
b) Ester formation:
O
H2C
CH2 C
+ HO
OH
OH
CH3
O
H2C
CH2 C
O
OH
CH3
+ H2O
Methyl-β-hydroxypropanoate
c) Amides formation:
O
H2C
CH2 C
OH
+ NH3
t=200o
O
H2C
OH
CH2 C
NH2
OH
+ H2O
amide of β-hydroxypropanoic acid
II. –OH group reaction:
a) hydrohalogens (HCl, HBr, HI, HF)
O
H2C
CH2
C
+ HCl
O
H2C
OH
OH
CH2 C
OH
+ H2O
Cl
b) can oxidize
O
H2C
OH
CH2
[O]
C
O
HC
OH
O
CH2
C
+ H2O
OH
β-oxopropanoic acid
Related to heat of:
1. α-hydroxyacids
lactic acid
2. β-hydroxyacids
3. γ-hydroxyacids
lactide
Decomposition α-hydroxyacids
O H O
СH3 С
C
H
O
к.H2SO4
O
CH3 C
t
+
H
OH
OH
Ethanal
HCOOH
к. Н2SO4, t
Ñ
ÑH2 COOH
ê. H2SO4
t
formic acid
CO + H 2O
OH
HOOCH2 C
H C
O
O
H C
OH
+
HOOCH2 C C CH2 COOH
acetidicarbonic acid
COOH
CO
H2O
2 CO2
H3 C C CH3
O
Representatives of hydroxyacids:
lactic acid. lactic acid is a trivial name
CH C
because at first it was extracted from milk. It
OH
is present in yogurt, sour milk and other milk
OH
products. It can form in muscles during hard and prolonged
work. Salts of milk acid are used in medicine.
O Malic acid. It is present in green apples and
C CH CH2 C
OHsome berries. It takes part in biological
OH
processes in human organisms and
organisms of other alive creatures. It is used in medicine for
synthesis of some medical preparations.
O
Tartaric acid . It is present in grape. It is
C
used in medicine for synthesis of some
OH
CH OH
medical preparations.
O
H3C
O
HO
CH
OH
O
C
OH
O
C
OH
CH2
HO
C
O
C
CH2
O
C
OH
OH
Citric acid . It is present in
orange, lemon and other
citric fruits. It takes part in
biological processes in
human organism.
Phenolacids.
Phenolacids are the derivatives of aromatic carboxyl acids that
contain –OH group (1 or more).
o-hydroxycinnamic acid
salicylic acid,
2-hydroxybenzoic acid
4-hydroxybenzoic acid
3,4,5-trihydroxybenzoic acid,
gallic acid
Chemical properties of phenolacids:
Chemical properties of phenolacids due to the
presence in their structure of carboxyl group, phenolic hydroxyl
and the aromatic nucleus.
COOH
COONa
+ NaHCO3
OH
+ CO2
+ H2O
OH
salicylic acid
COOH
+ FeCl3
OH
COO
O..
H
OH
salicylic acid
3
complex helatic salt of
salicylic acid
(violet colour)
Decarboxylation
COOH
Fe + 3HCl
t
+
OH
phenol
CO2
The best known aryl ester is O-acetylsalicylic acid, better
known as aspirin. It is prepared by acetylation of the phenolic
hydroxyl group of salicylic acid:
Aspirin possesses a number of properties that make it an
often-recommended drug. It is an analgesic, effective in
relieving headache pain. It is also an antiinflammatory agent,
providing some relief from the swelling associated with
arthritis and minor injuries. Aspirin is an antipyretic compound;
that is, it reduces fever. Each year, more than 40 million lb of
aspirin is produced in the United States, a rate equal to 300
tablets per year for every man, woman, and child.
Oxoacids
To oxoacids include aldehydo- and ketonoacids.
These compounds include in the structure of the
carboxyl group, aldehyde functional group or ketone
functional group.
glyoxylic acid,
oxoethanoic acid
acetoacetic acid,
3-oxobutanoic acid,
β-ketobutyric acid
oxalacetic acid,
oxobutanedioic acid,
ketosuccinic acid
pyroracemic acid,
2-oxopropanoic acid
γ-ketovaleric acid,
4-oxopentanoic acid,
levulinic acid
Chemical properties of oxoacids
1.
Decarboxylation of α-oxoacids
O
CH3
C
COOH
O
conc. H2SO4, t
CH3
H
acetaldehyd
pyroracemic acid
2.
C
+
CO2
Decarboxylation of β-oxoacids
O
CH3
C
CH2
COOH
acetoacetic acid
t
- CO2
CH3
C
O
acetone
CH3
Stereochemistry
 The
three-dimensional shape of an organic
molecule can have а dramatic effect upon
its reactivity. In fact, the study of the
shapes of organic molecules is so
important that it forms а separate subdiscipline within organic chemistry —
stereochemistry, from the Greek word
“” (stereos), meaning solid; this
chapter will be devoted to the study of
organic molecules in three dimensions.
Stereoisomers
 Compounds
which differ in the threedimensional arrangement of the atoms in
space but have the same connectivity are
termed stereoisomers.
 Stereoisomers are compounds that have
the same sequence of covalent bonds and
differ in the relative disposition of their
atoms in space.

1.
2.
There are two major causes of
stereoisomerism:
the presence of "structural rigidity" in а
molecule. Structural rigidity is caused
by restricted rotation about chemical
bonds. It is the basis for cis - trans
stereoisomerism,
а
phenomenon
found
in
some
substituted
cycloalkanes and some alkenes;
the presence of а chiral center in а
molecule.
COFORMATION
 The
methyl groups can rotate freely about
the central C–C bond. Structures that
differ only by rotation about one or more
single bonds are defined as
conformations of a compound.
 For example: Ethane has two
conformations: eclipsed structure, which
is more higher in energy than the more
stable staggered structure.
Configuration
 The
stereoisomers that are not easily
interconverted are called
configurational isomers.
Mirror Images

The concept of mirror images is the key to
understanding molecular handedness. All
objects, including all molecules, have mirror
images. The mirror image of an object is the
object’ reflection in а mirror. For example:
human hands.
Chirality
 The
general property of "handedness" is
called chirality. An object that is not
superimposable upon its mirror image is
chiral. If an object and its mirror image
can be made to coincide in space, then
they are said to be achiral.
A person’s left and right hands are not
superinposable upon each other.
Any organic molecule containing а single
carbon atom with four different groups
attached to it exhibits chirality.
 А chiral center is an atom in а molecule that
has four different groups tetrahedrally bonded
to it. It is asymmetric atom.
 Enantiomers
are stereoisomers whose
molecules are nonsuperimposable mirror
images of each other.

Properties of enantiomers
 Enantiomers
are said to be optically active
because of the way they interact with
plane-polarized light. An optically active
compound is а compound that rotates the
plane of polarized light.
 Ordinary
light waves - that is,
unpolarized light waves - vibrate in all
planes at right angles to their direction
of travel. Plane-polarized light waves,
by contrast, vibrate in only one plane at
right angles to their direction of travel.
Polarimeter
 An
enantiomer that rotates plane-polarized light
to the right is said to be dextrorotatory (the Latin
dexter means "right"). An enantiomer that
rotates plane-polarized light to the left is said to
be levorotatory (the Latin laevus means "left").
 А plus or minus sign inside parentheses is used
to denote the direction of rotation of planepolarized light by а chiral compound. The
notation (+) means rotation to the right
(clockwise), and (-) means rotation to the left
(counterclockwise). Thus the dextrorotstory
enantiomer of glucose is (+)-glucose.
 An
equimolar mixture of two
enantiomers is called а racemic
mixture, or а racemate. Since а
racemic mixture contains equal
numbers of dextrorotating and
levorotating molecules, the net optical
rotation is zero. А racemic mixture is
often specified by prefixing the name of
the compound with the symbol ( );
Diastereomers

Diastereomers - stereoisomers that are not
mirror images of each other.
 Epimers are diastereomers that differ only in
the configuration at one chiral center.
 In general, а compound that has n chiral
centers may exist in а maximum of 2n
stereoisomeric forms. For example, when
three chiral centers are present, at most eight
stereoisomers (23 = 8) are possible (four pairs
of enantiomers).