LECTURE № 1
THEME: Chemical bonds and mutual
influence of the atoms in the organic
compounds’ molecules.
Acidic and basic properties of the
organic compounds. Classification of
the organic reactions and reagents.
associate. prof. Ye. B. Dmukhalska, assistant. I.I. Medvid
Contents
Concept of organic chemistry.
Butlerov theory of structure of organic compounds.
Classification of organic compounds.
Nomenclature of organic compounds.
Types of the chemical bonds and their description
Hybridization of the atom orbitals: sp-, sp2-, sp3-.
Conjugate systems.
Inductive effect. Mesomeric effect.
Methods of ascertainment of the structure of organic
compounds.
Acidic and basic properties of the organic compounds.
Classification of the organic reactions and reagents.
We can designate the formula of organic
compound next ways:
structural formula (complete, shorten, simply).
molecular formula.
Complete structural formula:
H
H
H
C
H
C
H
C
H
H
C
H
H
H
H
H
C
C
C
C
C
H
H
H
H
H
butane
H
C
H
H
H
H
hexane
Shorten structural formula:
H2
C
H2C
CH2
H2C
CH2
CH3—CH2—CH2—CH3
butane
C
H2
hexane
Simply structural formula:
butane
hexane
Molecular formulas:
2 types:
ethanol C2H5OH
C2H6O
Models of the molecule of methane
3. Classification of organic
compounds
Functional group classification
Name of class of organic
compounds
Functional group
General formula of class of
organic compounds
Halogen carbonhydrates
—F, —Cl, —Br, ––I
R—Hal
Alcohols, phenols
—OH
R—OH
Thioalcohols, thiophenols
—SH
R— SH
Simple ethers
—OR
R—O—R
O
Aldehydes
O
C
R
C
H
H
O
Ketones
O
R
C
C
R
O
Carbon acids
O
C
R
C
OH
Sulfoacids
—SO3—H
OH
R—SO3—H
O
Complex ethers
C
O
O
R
C
O
Amides
C
O
O
R
NH2
Nitryles
—C  N
R—C  N
Nitrocompounds
—NO2
R—NO2
Amines
—NH2
R—NH2
C
NH2
R
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
O
group.
C
H
OH
All organic compounds concerning to the same
class form the homological row – it is the row of
organic compounds in which each next matter
differ —CH2— group from previous one.
i.e.
Alkanes
Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10
Pentane C5H12
Hexane C6H14
Heptane C7H16
Octane C8H18
Nonane C9H20
Decane C10H22
Undecane C11H24
Dodecane C12H26
Nomenclature of organic compounds
Nomenclature of organic compounds had been formed during last
centuries.There are:
Trivial.
Rational.
IUPAC (International Union of Pure and
Applies Chemistry) nomenclature.
Trivial nomenclature. At first organic compounds were
named by chance, for example, because the natural sources
of its receiving or their properties (citric acid, formic acid).
Many trivial names of organic compounds are used
nowadays.
Rational nomenclature. It was the first nomenclature in
which the structure of molecule was considered.
CH4
methane
CH3—CH3
methylmethane
CH3—CH2—CH3
dimethylmethane
IUPAC nomenclature. The IUPAC system is the most
rational and widely used system of nomenclature in
organic chemistry. The most important feature of this
system is that any molecular structure has only one name.
The IUPAC name of anyorganic compound consists of 3 parts:
root.
suffix (primary, secondary).
prefix (primary, secondary).
1. Word root. It is the basic unit of the name. It denotes the
number of carbon atoms present in the principal chain (the
longest possible continuous chain of carbon atoms including
the functional group and the multiple bonds) of the organic
molecule. For chains from one to four carbon atoms, special
word roots (based upon the common names of alkanes) are
used but for chains of five or more carbon atoms, Greek
number roots are used as given below:
2. Suffix. There are two types of suffixes:
a) Primary suffix. А primary suffix is always added
to the word root to indicate whether the carbon chain
is saturated оr unsaturated.
Type of carbon chain
Primary
suffix
General name
Saturated
ane
Alkane
Unsaturated with one double bond
ene
Alkene
Unsaturated with one triple bond
yne
Alkyne
Unsaturated with two double bonds diene
Alkadiene
Unsaturated with two triple bonds
Alkadiyne
diyne
The following examples illustrate the usage of word
roots and primary suffixes in naming of organic
compounds:
Organic compound
Word
root
Primary
suffix
IUPAC
name
CH3CH2CH2CH3
But
ane
Butane
CH2=CHCH3
Prop
ene
Propene
CHCH
Eth
yne
Ethyne
CH2=CH–CH=CH2
Buta
diene
Butadiene
CHCH–CHCH
Buta
diyne
Butadiyne
b) Secondary suffix. А secondary suffix is added to the
primary suffix to indicate the nature of the functional groups
are present in the organic compound. Secondary suffixes of
some important functional groups are given below:
The following examples illustrate the usage of the word
root, primary suffix and secondary suffix in naming of
the organic compounds:
Organic compound
Word
root
Primary Secondary
suffix
suffix
IUPAC name
СН3СН2ОН
Eth
ane
ol
Ethanol
СН3СН2СН2NH2
Prop
ane
amine
Propanamine
СН3СН2СН2COOH
But
ane
oic acid
Butanoic acid
СН3СН2СN
Prop
ane
nitrile
Propanenitrile
СН2=СНСНO
Prop
ene
al
Propenol
СНСНСOOН
Prop
yne
oic acid
Propynoic acid
3. Prefix. There are two types of prefixes:
a) Primary prefix. А primary prefix is used simply to
distinguish cyclic from acyclic compounds.
For example
Cyclo
Primary prefix
pent
Word root
ane
Primary suffix
Cyclopentane
IUPAC name
If the prefix cyclo- is not used, it simply indicates that the
compound is acyclic or with open chain.
b) Secondary prefix. In IUPAC system the nomenclature of
the certain groups is not considered as functional groups but
instead are treated as substituents, these groups are called
secondary prefixes and are added order to denote the side
chains or substituent groups. The secondary prefixes for
some groups which are always treated as substituent groups:
The following examples illustrate the usage of word
root, primary and secondary prefixes and suffixes in
naming of organic compounds:
Organic
Secondar Word Primar IUPAC name
compound
prefix
root
suffix
СН3СН2–Br
Bromo
eth
ane
Bromoethane
СН3–NO2
Nitro
meth
аnе
nitromethane
eth
аnе
Ethoxyethane
С2Н5–O–С2Н5 Ethoxy
In the case of carbocyclic compounds primary prefixes are
also used. For example,
4-Bromo
cyclo
hex
Secondary Primary Word
prefix
prefix
root
an (е)
1-ol
Primary Secondary
suffix
suffix
4-Bromocyclohexan-1-ol
correct
Sum of the locants = 3 + 4 = 7
Set of locants = 3, 4
correct
Sum of the locants = 2+ 2+ 4 = 8
Set of locants = 2,2,4
wrong
Sum of the locants = 4 + 5 = 9
Set of locants = 4,5
wrong
Sum of the locants = 2+ 4+ 4 = 10
Set of locants = 2,4,4
Types of the chemical bonds and their description
In the molecule all atoms have influence on each other.
The result of this influence is called electronic bonds.
There are 4 types of chemical bonds:
Covalent bond. This is the main type of bond in organic
chemistry. It formed is between atoms with similar
electronegativity. In this case common electronic cloud is
formed.
C + 4H
H
H C H
H
Polar bond. This is a covalent bond between 2 atoms with
different electronegativity in which electron pair is not
shared equally. But the difference of electronegativity is
not big.
CH3 Cl
CH3
Cl
Ion bond. This is a bond between 2 atoms with different
electronegativity (difference of electronegativity is very
big).
NaCl → Na+ + Cl–
Donor-acceptor bond. This is a type of covalent bond, but it has
different origin. In covalent bond a pair of electrons consists of 2
electrons from 2 atoms. But in donor-acceptor bond only one atom gives
2 electrons, but another atom accepts one electron.
acceptor
H
H
N
H
+
+ H
H
H
N H
H
donor
Semipolar bond. This is a type of donor-acceptor bond,
then one atom has 2 free electrons, and another atom has 6
electrons.
H3C
H3C
H3C
H3C
N + O
H3C
H3C
+ N O
Hydrogen bond. This bond is formed between atom of H+
and negative atom. This bond is designated as 3 points (…).
H-O ... H-O ... H-O
H
H
H
0,176 nm
0,099 nm
H3C
C
O... HO
OH ...O
C
CH3
Hybridization of atom orbitals: sp-,
sp2-, sp3Atom orbital is the space where the atom can be. There are
s–, p– and d–atom orbitals.
s-orbital
p-orbital
d-orbital
sp3–hybridization of atom orbitals. This
hybridization is formed when s–orbital joined
to 3 p–orbitals.
+
s-orbital
p-orbitals
sp3-hybrid
orbitals
The Carbon atom forms covalent bonds in the molecule of
organic compounds. There are 2 types of covalent bonds:
- and -bonds.
-bond is formed after joining of two different atomic
orbitals (s- and p-orbitals) or two hybrid orbitals (sp3hybrid orbitals):
H
H
H
C
C
H
H
H
sp2–hybridization of atom orbitals. This
hybridization is formed when s–orbital joined to
2 p–orbitals.
+
s-orbital
p-orbitals
sp2-hybrid
orbitals
-bond is formed after joining of two identical s- or
p-orbitals.
H
H
H
C
C
H
H
H
In organic compounds the atom of Carbon has hybrid
orbitals. There are 3 main types of them:
sp–hybridization of atom orbitals. This hybridization
is formed when s–orbital joined to p–orbital.
+
s-orbital
p-orbital
sp-hybrid
orbitals
Electronic effects in organic compounds
In organic compounds there are 2 types of electronic
movement of electronic density:
-inductive effect.
-mezomeric effect.
Inductive effect is the movement of electronic density by
-bonds.
i.e.
’’’+ ’’+ ’+ +  CH3—CH2—CH2—CH2Cl
Structural effects such as this that are transmitted through
bonds are called inductive effects. The atom of Chlorine has
larger electronegativity than the atom of Carbon. That’s why
the atom of Chlorine takes electronic density, and electronic
density of the molecule moves to atom of Chlorine. So:
’’’+ <’’+ <’+<+
But inductive effects are only part of the story. When
nitric acid transfers its proton to water, nitrate ion is
produced.
Nitrate ion is stabilized by electron delocalization, which we
can represent in terms of resonance between three
equivalent Lewis structures:
The negative charge is shared equally by all three
oxygens. Stabilization of nitrate ion by electron
delocalization increases the equilibrium constant for
its formation.
Mezomeric effect
Mezomeric effect is the movement of electronic density by -bonds or conjugate
systems.
Positive mezomeric effect have substituents that give electrons in a
conjugated system, negative – that attract electron density from conjugated
system.
Acidity and basicity of organic compounds.
Classification of the organic
reactions and reagents.
1. Accession reactions
 Electrophilic accession(AE)
 Nucleophilic accession(AN)
 Free radical accession (AR)
 Molecular accession
2) Substitution reactions
 Electrophilic substitution (SE)
 Nucleophilic substitution (SN)
 Free radical substitution (SR)
3) Elimination reactions
4) Regrouping reactions
5) Oxidation-reduction reactions
The end