Organic chemistry studies carbon compounds and their properties. Carbon atoms can form stable chains and rings due to their ability to form single, double, and triple bonds. This results in millions of possible organic compounds. Many organic compounds are important for biological processes and industrial applications such as pharmaceuticals, polymers, and fuels. The main types of bonds in organic compounds are covalent bonds, which involve sharing electron pairs between atoms. Hybridization of atomic orbitals allows carbon to form different structures by combining its s and p orbitals.

1. • Features of carbon compounds, their diversity, the role of living
nature and practical human activity.
Organic chemistry is a branch of chemistry that studies carbon compounds.
The term was introduced by the Swedish chemist Y.Ya. Berzelius in 1808.
Organic chemistry studies the properties of organic compounds and methods
of their preparation
Organic compounds are hydrocarbons and their derivatives. Hydrocarbon
derivatives contain functional groups - atoms or groups of atoms that determine the
characteristic chemical properties of the compound and its belonging to a certain
class of compounds.

2. Why compounds of one element - carbon - must be considered separately
from the rest?
1. The number of carbon compounds is huge
Carbon atoms are able to bond with each other, forming stable chains and cycles,
which makes the number of carbon compounds in principle infinite.
Carbon is able to form single, double and triple bonds and stable bonds with other
elements. This determines the huge variety of organic compounds.
Organic chemistry Inorganic chemistry
Number of compounds
~12 millions. (1999) ~ 7 millions. (1999)

3. 2. Carbon compounds are of great practical importance
Organic chemistry is the basis of biological chemistry, molecular biology and
pharmacology and the theoretical basis for the production of plant protection
products, detergents, dyes, polymers, various petroleum products, etc..
N
N N
H
N
NH2
N
H
N
H
O
O
N
H
N N
H
N
O
N
H2
метаболиты
N
H
N N
H
N
S
N
H
N
H
O
O
F
N
H
N N
H
N
S
N
H2
6-меркаптопурин 6-тиогуанин 5-фторурацил
антиметаболиты
6-mercaptopurine 6-thioguanine 5-fluorouracil
Metabolites
Antimetabolites
N
N
O
CH2
H
OH
H
OH
H
H
N
+
CONH2
O
P
O
O
H
O
P
O
H O
O
O
CH2
H
OH
H
OH
H
H
N
N
NH2
H
H
N
N
O
CH2
H
OH
H
OH
H
H
N
CONH2
O
P
O
O
H
O
P
O
H O
O
O
CH2
H
OH
H
OH
H
H
N
N
NH2
H H
NAD+ NADH
COOH
N
H2
Folic acid
PABA
SO2NH2
N
H2
Sulfanilamide

4. Cycle of tricarboxylic acids
C
CH2
COOH
COOH
O
C
CH2
COOH
O
H COOH
CH2
COOH
C
CH2
COOH
COOH
CH
COOH
C
H
CH2
COOH
COOH
CH
COOH
O
H
C
H
CH2
COOH
COOH
C
COOH
O
CH2
CH2
COOH
C
COOH
O
CH2
CH2
COOH
C
SKoA
O
CH2
CH2
COOH
COOH
C
H
CH
COOH
COOH
C
H
CH2
COOH
COOH
OH

5. A brief history of organic chemistry
Empirical period
In the 17th and 18th centuries a large number of organic compounds were
obtained in individual form, such as, for example, oxalic, citric, malic, uric,
formic acids, urea, etc.
Analytical period
This is the 18th century - the middle of the 19th century.
All organic compounds contain carbon.
Two theories were created - the theory of radicals and the theory of types. The
concept of "vital force" and the concept of "vitalism", which asserted the presence
of a certain intangible "vital force" (vis vitalis) in organisms, with the help of
which the body synthesizes complex organic substances.
The first organic synthesis was carried out by the German chemist F. Weller in
1828 by heating an inorganic compound - ammonium isocyanate, while urea was
formed:
NH4OCN CO(NH2)2
t

6. Structural stage
19th century - beginning of the 20th century
German chemists A. Kekule and G. Kolbe established the tetravalency of carbon
and expressed an opinion about the ability of carbon atoms to connect into long
chains.
Chemist A.M. Butlerov created a structural theory :
 " structure " - sequence of atoms and bonds between atoms in a molecule
 structure determines the chemical and physical properties of substances
The Dutch chemist Y.Kh. Van't-Hoff and the French chemist J.A. Le Bel's idea of
the spatial three-dimensional structure of organic molecules (1874).

7. CH3 CH2 CH2 CH2 OH
CH3 CH2 CH OH
CH3
CH3 CH CH2 OH
CH3
CH3 C OH
CH3
CH3
н-бутиловый спирт
втор-бутиловый спирт
изобутиловый спирт
трeт-бутиловый спирт
CH3 C OH
CH3
CH3
Zn(CH3)2
O
H2
CH3 C
Cl
O
n-butyl alcohol
sec-butyl alcohol
iso-butyl alcohol
tert-butyl alcohol

8. Modern period
Development of synthetic organic chemistry;
Introduction of quantum-mechanical concepts and
physical methods of studying substances;
Close connection with other disciplines - with
physical, inorganic, biological and coordination
chemistry.

9. Classification of organic compounds
Classification of organic compounds according to the carbon skeleton.
Hydrocarbons
Acyclic aliphatic
(open chain)
Saturated
(alkanes)
Unsaturated
(Alkenes, alkynes,
alkadienes, etc.)
Cyclic
(closed circuit)
Alicyclic
(cycloalkanes,
cycloalkenes, etc.)
Aromatic
(arenas)
Heterocyclic
C
H3 CH3 C
H2 CH2 C
H CH
C
H2 CH CH CH2
N
O

10. Classification of organic compounds by functional groups
Таблица 1. Классы органических соединений
Class Functional group Example
carboxylic acids carboxyl group
sulfonic acids sulfo group
halides halocarbonyl
esters Alkoxycarbonyl
C
O
OH
COOH
C
O
OH
CH3
S
O
O
OH
SO3H
SO3H
C
O
Cl
COCl
C
O
Cl
CH3
C
O
O R
COOR
C
O
O
CH3
C2H5

11. amides carboxamide (amide)
nitriles nitrile
aldehydes formal, aldehyde
ketones oxo group, keto group, carbonyl group
alcohols and
phenols
hydroxy group, oxy group
C
O
NH2
CONH2
C
O
NH2
CH3
C N
CN
CH3 C N
C
O
H
CHO
C
O
H
CH3
C
O
C
H3 C
O
CH3
OH
C2H5OH

12. mercaptans, thiols mercapto group, thio group, sulfanyl
group
amines amino group
simple ethers (Ethers) Alkoxy group
nitro compounds nitro group
nitrosocompounds nitroso group
halogen derivatives -F, -Cl, -Br, -I halogen
SH
C2H5SH
NH2 C2H5 NH2
O R C2H5 O C2H5
N
O
O
+
NO2
CH3NO2
N O
NO
NO
C2H5Cl

13. Chemical bond in organic compounds
A chemical bond is an interaction between atoms that leads to the formation
of molecules or crystals.
There are two main types of chemical bonds in organic compounds:
covalent and ionic.
Chemical bond
Covalent
Covalent polar
Covalent non-
polar
Ionic

14. Ionic bond
It is rarely found in organic compounds
C
+
N N
N
C
H3
CH3 CH3
CH3
C
H3
CH3
Cl
C
NO2
NO2
O2N
Na
+
CH3 COO
-
Na
+

15. Covalent bond
The covalent bond is the main one in organic compounds. Such a
connection is formed by sharing a pair of electrons of two atoms.
H. H
.
+ H.H
.
C
H
H
H
. C
H
H
H
.
+ C
H
H
H
.C
H
H
H
.

16. Classification of covalent bonds
By polarity
C
H
H
H
C
H
H
H
C C
H
H
H
H
C C
H H
C
H
H
H
C
H
OH
H
C C
H
H
H
Cl
C C
H Cl

17. By the symmetry of the orbitals
σ-bond – covalent bond formed when atomic orbitals overlap
along the axis connecting the nuclei of atoms:
. .
s s
. .
s sp3
.
sp3 sp3
.

18. π-bond – covalent bond arising from lateral overlap of non-
hybrid p-orbitals. At the same time, localized p-atomic orbitals
are delocalized, forming p-orbitals:
. .
двe p-атомныe орбитали
. .
-связывающая молeкулярная орбиталь
Two p-atomic orbitals π- bonding molecular orbital

19. Donor-acceptor mechanism.
Bond formation takes place due to a pair of donor electrons and a vacant
(free) orbital of the acceptor.
H. H
. + H.H
.
+
-
Semipolar bond, which is the result of both covalent interaction and the
attraction of opposite charges :
N
CH3
C
H3
CH3
.
. O
...
.
.. N
CH3
C
H3
CH3
.
.O
...
.
..
N
CH3
C
H3
CH3
O N
+
CH3
C
H3
CH3
O

20. Classification of covalent bonds by bond order
1. Single (one σ-bond), for example, between carbons in the ethane
molecule;
2. Double (1 σ-bond and 1 π-bond), for example, in the ethylene
molecule;
3. Triple (1 σ-bond and 2 π-bonds), as, for example, in the acetylene
molecule.
C
H
H
H
C
H
H
H
C C
H
H
H
H
C C
H H

21. Hybridization
Electronic structure of a carbon atom
1s2 2s2 2p2
1s2 2s1 2p3
C
H
H
:
C
H
H
H
H

22. sp3- hybridization
In this case, the energies of one 2s and three 2p-orbitals are
equalized, while 4 identical sp3-orbitals are formed :
C
H
H
H
H
109o28'
C
H
H
H
H

23. sp2- hybridization
The energies of one 2s and two 2p-orbitals are equalized, while
3 identical sp2-orbitals are formed and one non-hybrid p-orbital
remains :
Three sp2-hybrid orbitals participate in the formation of three
σ-bonds: for example, in ethylene :
C C
H
H
H
H
~120o
~120o
~120o

24. sp- hybridization
In this case, the energies of one 2s and one 2p-orbital are equalized, while 2
identical sp-orbitals are formed and two p-orbitals remain non-hybrid :
Two sp-hybrid orbitals repel each other, while the electron density maxima are
located on the same straight line
x
Two non-hybrid p-orbitals are located perpendicular to each other in the same plane,
which is perpendicular to this line x:
x
y
z
y

25. The acetylene molecule contains carbon atoms in the state of sp-hybridization
C C H
H
180o
Due to hybrid orbitals, bonds with hydrogen atoms and σ-bond between carbon
atoms are formed:
x
Non-hybrid π-orbitals overlap, forming two π-bonds:
H H H C C H

26. Other types of interactions
Hydrogen bond - the attraction of a protonated hydrogen atom attached to
an atom of an electronegative element to another atom carrying a negative
charge.
H F H F
... H F
...

27. In the α-structure of proteins, every first and fifth amino acid
residues form hydrogen bonds with each other, forming a
helix:
N
H
CH C
O
C
O
CH
N
CH3
H
N CH
CH2
H
C
O
CH
C
CH
O
CH3
CH3
C
O
CH
N
CH2
H
N
CH2
H
OH
CH
C
H3
CH3

28. Hydrogen bonds between complementary bases in the DNA
double helix: three hydrogen bonds form between adenine and
thymine, and two bonds form between guanine and cytosine:
N
N
N
O
H
H
R
N
N
N
N O
R
N
H
H
H
. . .
. . .
. . . N
N
O
O R
H
CH3
N
N
N
N N
R
H
H
. . .
. . .