Carbon forms a huge number of compounds due to its ability to form strong bonds with itself and other elements. The study of carbon-based compounds is called organic chemistry. Organic compounds are classified based on their carbon skeleton and functional groups. Key aspects of organic chemistry include structural and stereoisomers, functional groups that determine reactivity, and IUPAC nomenclature for systematic naming.

1. BY
VANA JAGAN MOHAN RAO M.S.Pharm, MED.CHEM
NIPER-KOLKATA
Asst.Professor, MIPER-KURNOOL
Email: jaganvana6@gmail.com

2. Carbon forms a huge number of compounds.
The study of the structures, reactions and
properties of these carbon-based compounds is
called organic chemistry.
 Note:
◦ Carbon monoxide, carbon dioxide, metal carbonates and
metal cyanides are not classified as organic compounds.
What is Organic Chemistry?

3. Bonding Nature
of Carbon
Tetravalent
• Carbon forms four bonds.
• Due to strong C−C bond, it
can bond with itself to form
stable straight or branched
chains, or ring structures.
Strong C−C bonds
• C−C bonds are much stronger
than bonds between atoms of
other elements.
Bond Bond energy
/ kJ mol−1
C−C 350
Si−Si 222
N−N 160
O−O 150
Multiple bonds
• Carbon can also form
single, double or triple
bonds with itself.
• Carbon compounds can
have varying degree of
unsaturation.
Why does carbon form so many
compounds?

4. Organic Compounds
Aliphatic
Alicyclic
(closed ring)
Open-chain
• Straight-chain
• Saturated
• Unsaturated
Aromatic
• Branched chain
OH
O
• Contains one
or more
benzene rings
Cl
Classification according to Carbon Skeleton

5. Organic compounds in the same
homologous series:
Example: alkene
• possess the same general formula CnH2n
• differ from the previous member in the
series by a −CH2− group
CH2=CH2, CH2=CHCH2−H,
CH2=CHCH2CH3, CH2=CHCH2CH2CH3
• possess similar chemical properties,
due to the presence of same functional
group
• Alkenes possess a carbon-carbon
double bond.
• Alkenes undergo electrophilic
addition reactions.
• show gradual change in physical
properties due to increased molecular
size and mass, caused by longer
carbon chains
Etheneb.p. = −102 °C
Propeneb.p. = −48 °C
1-Butene b.p. = −6.5 °C
1-Pentene b.p. = 30 °C
HOMOLOGOUS SERIES

6. A functional group is an atom or a group of atoms
that governs the chemical properties of an organic
molecule.
FUNCTIONAL GROUPS

7. where R, R1, R2 represent alkyl groups, −CnH2n+1
FUNCTIONAL GROUPS

8. Class of compound Functional group Name of functional group
Hydroxy compounds
RCH2OH Primary alcohol
RR1CHOH Secondary alcohol
RR1R2COH Tertiary alcohol
C6H5OH Phenol
Carbonyl compounds
RCHO Aldehyde
RR1CO Ketone
where R, R1, R2 represent alkyl groups, −CnH2n+1
FUNCTIONAL GROUPS

9. Class of compound Functional group Name of functional group
Carboxylic acids RCO2H Carboxylic acid
Carboxylic acid
derivatives
RCOCl Acyl chloride
RCO2R1 Ester
RCONH2 Amide
Amines
RNH2 Primary amine
RR1NH Secondary amine
RR1R2N Tertiary amine
Nitriles RC N Nitrile
where R, R1, R2 represent alkyl groups, −CnH2n+1
FUNCTIONAL GROUPS

10.  The structural formulae of organic
compounds may be represented using
◦ displayed formulae
◦ condensed structural formulae
◦ skeletal formulae
 Note that any structural formula given must give an
unambiguous structure.
◦ E.g. 1-propanol
✓CH3CH2CH2OH
C3H7OH ✗
Writing Structural Formulae

11.  Displayed Formulae
◦ Show both the relative placing of atoms and the number
of bonds between them.
◦ All bonds between atoms must be shown.
◦ Exception:
The following convention for representing the
aromatic ring is preferred:
Writing Structural Formulae

12.  Condensed Structural Formulae
◦ Each carbon atom is written separately.
◦ Following each of these carbon atoms,
 the other atoms that are bonded to this carbon atom are
written.
 Substituent groups that are bonded to this carbon atom are
enclosed in brackets.
◦ Similarly, the following convention for representing
the aromatic ring is preferred:
Writing Structural Formulae

13.  Skeletal Formulae
◦ Simplified representation derived from a structural
formula by removing hydrogen atoms (and their
associated bonds) and carbon atoms from alkyl
chains, leaving just the carbon-carbon bonds in the
carbon skeleton and the associated functional groups.
◦ The following convention for representing the
aromatic ring is preferred:
Writing Structural Formulae

14. Writing Structural Formulae

15. Writing Structural Formulae

16.  IUPAC Nomenclature is a system of naming
chemical substances developed by the
International Union of Pure and Applied Chemistry
(IUPAC).
 The IUPAC sets global standards for names,
symbols, and units used in chemical sciences.
IUPAC Nomenclature

17.  The IUPAC name for an organic compound consists of
the following parts:
Root Suffix(es)InfixPrefix(es)
No. of carbon atoms in
longest continuous carbon
chain, i.e. parent chain
Nature of
parent chain
Side chains & functional
groups of lower priority
1° suffix
Degree of
saturation or
unsaturation Functional group of
highest priority in
molecule
+ 2° suffix
IUPAC Nomenclature

18. root
(no. of carbon atoms
in parent chain)
1° suffix
(degree of
saturation) 2° suffix
(main functional group,
of highest priority)
side-chains &
functional groups of lower
priority, arranged in
alphabetical order
infix
(nature of
parent chain)
3-ethyl-4-methylhexane
3-methylcyclopentene 2-hydroxypropanoic acid
3-oxohe
x
a
n
al
1
2
3
Locants indicate
positions of
sustituent groups,
bonds etc. in
molecule
locant
locantlocant
IUPAC Nomenclature

19. -3,9-dione
root
(no. of carbon atoms
in parent chain)
1° suffix
(degree of
saturation)
2° suffix
(main functional group,
of highest priority)
side-chains &
functional groups of lower priority,
arranged in alphabetical order
Locants indicate positions of
sustituent groups, bonds etc.in
molecule
18-bromo-12-butyl-11-chloro-4,8-diethyl-5-hydroxy-15-methoxytricos-6,13-diene-19-yne
tricos 23 carbons
IUPAC Nomenclature

20.  Punctuation rules:
◦ Di-, tri- etc. are not taken into consideration when arranging
side-chains and functional groups alphabetically.
◦ Commas are placed between numbers.
◦ Hyphens are placed between a number and a letter.
◦ All parts are connected either by merging successive names,
including commas or hypens to form a one-word name.
IUPAC Nomenclature

21.  Functional groups control the chemistry of organic
molecules.
They contain reactive sites:
◦ Electron deficient sites
 E.g. a carbon atom bonded to a more
electronegative bromine atom
◦ Electron rich sites
 E.g. a π-system in an alkene or a benzene ring
ORGANIC REACTIONS

23. Types of
Bond Fission
Homolytic
• When a covalent bond between two
atoms breaks, each atom retains one
bonding electron.
• Free radicals are formed.
• A free radical is an electrically neutral
atom or group of atoms that has one
unpaired electron. It is unstable and
highly reactive.
Cl−Cl→Cl + Cl
Heterolytic
• When a covalent bond between
two atoms breaks, one of the
atoms retains both the bonding
electrons to bear a negative
charge.
• The other atom bears a positive
charge.
H−Cl→ H+ + Cl:−
ORGANIC REACTIONS

24. Types of
Reagents
Nucleophile
• A reagent that is attracted to
regions of positive charge or
electron deficient sites
• An electron pair donor
• Good bases are generally
good nucleophiles
Negative ions: H−O:−,N C:−
Neutral molecules: H2O:, :NH3
• A reagent that is attracted to
regions of negative charge
or high electron density
• An electron pair acceptor
Electrophile
2Positive ions: NO +
δ+ end of an induced dipole: Br−Brδ+ δ−
δ+ end of a permanent dipole: δ+H−Clδ−
ORGANIC REACTIONS

25.  Isomers are molecules that have the same
molecular formula but differentarrangement of atoms
in space.
ISOMERISM
Structural isomerism
• Same molecular formula
• Different structural formulae
Stereoisomerism
• Same molecular formula
• Same structural formula
• Different spatial arrangement
of atoms in 3D space
Chain
isomerism
Functional
isomerism
Positional
isomerism
Cis-trans
isomerism
Optical
isomerism
ISOMERISM

26.  Chain Isomerism
◦ Arises due to the different arrangement of carbon atoms in
a carbon chain.
◦ E.g. isomers of hexane, C6H14
STRUCTURAL ISOMERISM

27.  Positional Isomerism
◦ Arises due to the different positions assumed by a
functional group on a carbon chain or ring.
OH
OH
pentan-1-ol pentan-2-ol
O H
pentan-3-ol
CH3
Cl
CH3 CH3
2-chloromethylbenzene
Cl
3-chloromethylbenzene
Cl
4-chloromethylbenzene
STRUCTURAL ISOMERISM

28. STRUCTURAL ISOMERISM

29.  Cis-trans (a.k.a. geometric) isomerism
[Use of E-Z nomenclature is not required.]
◦ Criteria:
 Restricted rotation about a double bond, e.g. carbon-
carbon double bond, or
 Restricted rotation due to a rigid ring structure
 Two different substituent groups attached to each atom in a
double bond, e.g. to each carbon atom in a carbon-carbon
double bond
STREOISOMERISM

30. Examples of cis-trans isomers arising from:
Restricted rotation about a double bond
STREOISOMERISM

31. Examples of cis-trans isomers arising from:
Rigid ring structure
STREOISOMERISM

32.  Optical isomerism
◦ Criteria:
 A chiral carbon, i.e. an asymmetrical carbon atom with
four different substituent groups
 No plane of symmetry
◦ Optical isomers exist as a pair of non– superimposable
mirror images of each other.
◦ Optical isomers are also known as enantiomers.
STREOISOMERISM

33.  Enantiomers
◦ Identical chemical properties and physical properties
◦ Rotate plane of polarised light in opposite
directions
STREOISOMERISM

34.  Racemic mixture
◦ Equal amounts of both enantiomers.
◦ Optically inactive, as there is no net rotation of plane-
polarised light. Although both enantiomers rotate plane-
polarised light in opposite directions, the rotations cancel
out.

35.  Drawing optical isomers
◦ Optical isomers must be drawn as three- dimensional
structures according to the convention used in the example
below:
STREOISOMERISM