ORGANIC CHEMISTRY
 Organic chemistry is the study of carbon containing
compounds derived from living organisms.
 Oil is formed over millions of years from the break down of
dead creatures and plants.
80+ million
compounds- natural
& synthetic.

Crude Oil (petroleum) is a mixture of many thousands of these
different compounds and is the main source of many of these
chemicals.

They are called hydrocarbons because they predominantly
contain the elements hydrogen and carbon.
Distillation of Crude Oil
Distillation of Crude Oil
Homologous series
This is a series of compounds which all contain the same
functional group, and have similar chemical properties.
ALKANES
ALKENES
ALCOHOLS
CH4
CH2 =CH2
CH3OH
CH3-CH3
CH2 =CH –CH3
CH3CH2OH
Each has a general formula:
ALKANES: CnH2n+2
The members of the series differ by the number of CH2
units.
CH3-CH3, CH3-CH2-CH3, CH3-CH2-CH2-CH3
Graduation in physical properties: eg: boiling points.
CH4 (GAS), C8H18 (LIQUID), C30H62 (SOLID)
ALKANES
SATURATED HYDROCARBONS – contain maximum
amount of hydrogen - only single bonds (no multiple
bonds)
NAMING ALKANES
No of C
atoms
Prefix
1
Meth
2
Eth
3
Prop
4
But
5
Pent
6
Hex
7
Hept
8
Oct
All alkanes end
with ‘ANE’.
All belong to the same
HOMOLOGOUS series
GENERAL FORMULA
CnH(2n+2)
Functional
groups
The
functional
groups are
atoms or
combinations
of atoms
which
determine the
properties of
organic
molecules.
STRUCTURES OF ALKANES
METHANE CH4
Bond Angle
109.5o
Shape
Tetrahedral
H
Can be illustrated as:
H
C
H
H
ETHANE.
Molecular formula C2H6
Structural formula: CH3 CH3
or
H
H
H
C
C
H
H
H
PROPANE.
Molecular formula: C3H8
Structural formula: CH3 CH2 CH3 or
Both ethane and propane are
“straight” chain molecules
BUT!!
H
H
H
H C
C
C
H
H
H
H
Bonds are NOT 90o molecules are NOT STRAIGHT!!!
Schematic formula
BUTANE & ISOMERS.
Molecular formula: C4H10 - can have two different
structures
“Straight” chain. CH3 CH2 CH2 CH3
BUTANE
Schematic formula:
Branched chain CH3 CH
CH3
CH3
METHYL PROPANE
branch
Isomers
Compounds that have the same molecular formula but
different structural formula.
TASK:
Illustrate the structures of the three different
isomers of C5H12.
Names & Structures
Examples
CH3
2- methylbutane
CH3 CH CH2 CH3
CH3
CH3 C
CH3
2,2 – dimethyl propane
CH3
TASK: illustrate the structures of:
2-methylpentane.
CH3CH(CH3)CH2CH2CH3
2,3 – dimethylbutane.
CH3CH(CH3)CH(CH3)CH3
2,2,3 -trimethylpentane CH3C(CH3)2CH(CH3)CH2CH3
THE RULES FOR NAMING ORGANIC COMPOUNDS
1.
Choose the longest unbroken chain of Carbon atoms and assign a name for the
carbon chain using the prefixes; meth-1, eth-2 etc.
2.
Identify any carbon chain branches (alkyl groups). These are assigned names
using the same prefixes as above along with the suffix “-yl” – methyl, ethyl etc.
3.
Identify the functional groups present in the molecule. Assign a prefix or suffix
according to their homologous series. These will be written in front of the name
of the carbon chain.
4.
There is an order of precedence, to decide the suffix for the carbon chain:
COOH / C=C > OH > Br / Cl
5.
Number the Carbon atoms in the longest chain so that the branches/functional
groups have the lowest number possible. Allocate a number for every
group/branch no matter how many times it occurs. Where groups are on the same
carbon write their names in alphabetical order.
6.
Numbering takes precedence "wins" over alphabetical spelling. Prefixes are used
for groups that occur more than once.
Di – 2
7.
Tri – 3
Tetra – 4
Penta – 5 etc.
The final name is written as one word with commas between numbers, hyphens
separating numbers from words.
Give the names of the following alkanes
(a) CH3 CH2
CH
CH2 CH3
CH3
(b) CH3 CH
CH3
CH2
CH
CH3
CH3
(c) CH3 C(CH3)2 CH2 CH(CH3) CH2 CH3
(d) CH3CH2CH(CH3)C(CH3)3
Give the names of the following alkanes
(a) CH3 CH2
CH
CH2 CH3
3-methyl pentane
CH
2,4-dimethylpentane
CH3
(b) CH3 CH
CH3
CH2
CH3
CH3
(c) CH3 C(CH3)2 CH2 CH(CH3) CH2 CH3 2,2,4-trimethyl
hexane
(d) CH3CH2CH(CH3)C(CH3)3 2,2,3-trimethylpentane

Cyclic Alkanes
When C atoms bond together to form a ‘ring’ – known as
a ‘cyclic’ structure.
Example
What is the molecular
formula of this alkane?
How does the molecular
formula compare to the
general formula for alkanes?
Why does it belong to the
series of alkanes?
Can you think of a name
for this molecule
CYCLOHEXANE
Illustrate the cyclic
structures of (a) C4H8 and
(b) C5H10 and name the
molecules.
Structure of Alkenes
The shape around the double bond is planar.
The bond angle around the double bond is 120o
PLANAR
Represented as

C bond

C
C
C
120o
Examples of Alkenes
………………, C2H4
H
H
C
H
PROPENE
OR …………………….
C
H
CH2
CH
CH3
TASK: Use ball & stick models or sketches to construct and name 3
different structures for C4H8 each one with one double bond.
Examples of Alkenes
H
ETHENE, C2H4
H
C
H
H
C
PROPENE
C
H
H
OR CH2 CH2
C
H
CH2
CH
CH3
CH3
TASK: Use ball & stick models or sketches to construct and name 3
different structures for C4H8 each one with one double bond.
CH3CH2CH
CH3CH
CH2 BUT-1-ENE
CHCH3
BUT-2-ENE
CH3C
CH2 METHYL
PROPENE
CH3
More Alkenes
Illustrate structures of the following alkenes:
Pent-1-ene
Hex-3-ene
2-methylbut-1-ene
Cyclohexene
Name the following alkenes
CH3CH
CH2
CHCH2CH3
CHCH(CH3)CH2CH3
CH3CH(CH3)CH
(CH3)3CCH
CHCH2CH3
C(CH3)2
More Alkenes
Illustrate structures of the following alkenes:
Pent-1-ene
CH2 CHCH2CH2CH3
Hex-3-ene
CH3CH2CH CHCH2CH3
2-methylbut-1-ene
CH2 C(CH3)CH2CH3
Cyclohexene
Name the following alkenes
CH3CH
CH2
CHCH2CH3
CHCH(CH3)CH2CH3
CH3CH(CH3)CH
(CH3)3CCH
Pent-2-ene
3-methylpent-1-ene
CHCH2CH3
C(CH3)2
2-methylhex-3-ene
2,4,4-trimethylpent-2-ene
GEOMETRIC ISOMERS
 There is no rotation about the double bond.
GEOMETRIC ISOMERISM each C atom in the double bond has two
different atoms/groups attached.
BUT–2-ENE CH3 CH CH CH3
CH3
C
H
CH3
C
H
cis but-2-ene
CH3
C
H
C
H
CH3
trans but-2-ene
Geometric isomerism is a form of STEREOISOMERISM –
Same molecular and structural formula but atoms are arranged
differently in space
Alkynes
H-C≡C-H
Ethyne
H-C≡C-CH3
propyne
H-C≡C-CH2-CH3
But–1-yne
CH3-C≡C-CH3
But–2-yne
Very reactive
Triple bond unstable!
Attracts electrophiles.
Substituted alkane with at least one halogen atom
General formula CnH(2n+1)X
Structures & Names
CH3Cl
chloromethane
CH3–CH2 –CH2Br
1- bromopropane
2- iodobutane
CH3–CH–CH2 CH3
I
CH3–CH2–CH2–CH2Br 1- bromobutane PRIMARY 10
CH3–CH2–CH–CH3
Br
CH3
CH3 CH2–C–CH3
Br
2-bromobutane
SECONDARY 20
2-bromo-2-methylbutane
TERTIARY 30
General formula CnH(2n+1)OH Hydroxyl group
•CH3OH Methanol •CH3CH2OH Ethanol
•C3H7OH – two isomers
CH3—CH—CH3
CH3—CH2—CH2OH
Propan-1-ol 1o
OH
Propan-2-ol
TASK: C4H9OH has 4 isomers. Draw the
structures of each isomer giving the name
and class of each one.
2o
•FERMENTATION – sugars (glucose)/yeast/25oC – 35OC
C6H12O6 yeast
2C2H5OH + 2CO2
•HYDRATION OF ETHENE
CH2=CH2 + H2O
CH3CH2OH
Advantage
Fermentation
Hydration
Renewable sources
Low energy
Cheap
Disadvantage
Batch
Slow
Impure/Low yield
High energy
Fast
Pure
Non-renewable
High yield /continuous
Expensive
KNOWN AS CARBONYLS
STRUCTURE
C
BOND ANGLE 120O
O
ALDEHYDES
GENERAL STRUCTURE
HCHO - methanal
R
C
H
EXAMPLES
O
CH3CHO - ethanal
CH3CH2CHO - NAME?
 Illustrate the structures of these examples
KETONES
GENERAL FORMULA
R
C
O
R and R1 may be the
same or different
R1
NOTE: ALDEHYDES & KETONES EXHIBIT FUNCTIONAL GROUP ISOMERISM
EXAMPLES
CH3COCH3
propanone
CH3COCH2CH3
butanone
CH3CH2COCH2CH3 pentan-3-one
 Illustrate the
structures of these
examples – show &
name the
corresponding
aldehyde isomer.
Carboxylic Acids
GENERAL FORMULA
R
C
O
OH
Acidic reaction
Carboxyl group
-COOH
CH3COOH + H2O  ……………………………. + H3O+
EXAMPLES
HCOOH
................... acid
 Illustrate the
structures of these
examples – show &
CH3COOH .................... acid
name the
corresponding
CH3CH2COOH .......................... acid aldehyde isomer.
Carboxylic Acids
GENERAL FORMULA
R
C
O
OH
Acidic reaction
Carboxyl group
-COOH
CH3COOH + H2O  CH3COO- + H3O+
EXAMPLES
HCOOH
methanoic acid
CH3COOH
ethanoic acid
CH3CH2COOH propanoic acid
 Illustrate the
structures of these
examples – show &
name the
corresponding
aldehyde isomer.
FORMATION OF ESTERS
• GENERALLY: .........+ ........... ESTER + WATER
catalysed by H+ ions normally from conc. H2SO4
O
O
R C +
H O R/
R C
+ H2O
OH
O R/
H
C
O
+
OH
methanoic
CH3OH
methanol
CH3CH2OH + CH3CH2COOH
ethanol
propanoic
H
C
O
+
H2O
O CH3
............. ..........................
CH3CH2........CH2CH3 + H2O
............ .........................
FORMATION OF ESTERS
• GENERALLY: ACID + ALCOHOL
ESTER + WATER
catalysed by H+ ions normally from conc. H2SO4
O
O
R C +
H O R/
R C
+ H2O
OH
O R/
H
C
O
+
OH
methanoic
CH3OH
methanol
CH3CH2OH + CH3CH2COOH
ethanol
propanoic
H
C
O
+
H2O
O CH3
methyl methanoate
CH3CH2COOCH2CH3 + H2O
ethyl propanoate
NAMING OF ESTERS
GENERALLY:
ACID + ALCOHOL
ESTER + WATER
ESTER NAME: .......................YL
CH3CH2OH + CH3CH2COOH
ethanol
propanoic
methanoic methanol
............ANOATE
CH3CH2COOCH2CH3 +H2O
.........yl ............anoate
..............hyl ..........anoate
NAMING OF ESTERS
GENERALLY:
ACID + ALCOHOL
ESTER + WATER
ESTER NAME: ALCOHOLYL
CH3CH2OH + CH3CH2COOH
ethanol
propanoic
methanoic methanol
ACIDANOATE
CH3CH2COOCH2CH3 +H2O
ETHyl PROPanoate
METHyl METHanoate
HYDROLYSIS OF ESTERS
• Hydrolysis can take place in either acid or alkaline
solution
• Hot alkaline solution is usually preferred
• Ester is hydrolysed to alcohol and sodium salt of acid.
Generally RCOOR’ + NaOH
ROO-Na+ + R’OH
EXAMPLES
CH3COOCH2CH3 + NaOH
CH3COO-Na+ + CH3CH2OH
ethyl ethanoate
sodium ethanoate ethanol
CH3CH2COOCH3 + NaOH
CH3CH2COO-Na+ + CH3OH
methyl propanoate
sodium propanoate methanol
• Addition of dil.H2SO4 or dil. HCl to sodium salt
regenerates the carboxylic acid.
USES OF ESTERS
esters have characteristic
sweet smells and are used as
food .................
they are also widely
used as ............
and as ...................
USES OF ESTERS
esters have characteristic
sweet smells and are used as
food flavourings.
they are also widely
used as solvents
and as plasticisers
NATURALLY OCCURING ESTERS
• Occur as fats and oils, known as triglycerides
• Triesters of long-chain carboxylic acid and
propane –1,2,3-triol (glycerol).
• On hydrolysis using hot NaOH, 3 moles of long
chain acid are produced together with 1 mole of
glycerol.
C17H35COOCH2
CH2OH
C17H35COOCH + 3NaOH
CHOH + 3C17H35COONa
C17H35COOCH2
CH2OH
sodium
glycerol
stearate
Sodium stearate is used in the manufacture of soap.
AMINES
H
N
H
H
C
H
N
H
H
H
H
H
H
H
N
C
H
H
N
H
H
H
AMIDES
O
H
H
C
C
H
O
H
C
C
C
N
H
H
N
H
O
H
H
H
H
H
H
H
H
C
C
H
C
N
H
H
H
C
H
H
Physical Properties
Recognize and apply to particular examples the relationship between melting
points, boiling points, vapour pressure, viscosity and intermolecular forces
(hydrogen bonding, Van der Waals forces including dispersion or London
forces number and type of functional group, chain length, branched chains)
Addition reactions
• Unsaturated compounds undergo addition reactions to form saturated
compounds e.g.
CH2=CH2 + Cℓ2 → CH2Cℓ-CH2Cℓ • hydrohalogentaion - addition of HX - halogenation - addition of X2 –
• hydration - addition of H2O –
•
The X-atom or OH-group attaches to the more substituted C-atom.)
• hydrogenation - addition of H2 (During additon of HX and H2O to
unsaturated hydrocarbons, the H-atom attaches to the C-atom already
having the greater number of H-atoms. ·
Elimination reactions
• * Saturated compounds (haloalkanes, alcohols, alkanes) undergo
elimination reactions to form unsaturated compounds e.g. CH2CℓCH2Cℓ → CH2=CHCℓ + HCℓ
• - dehydrohalogentaion - elimination of HX from a haloalkane (alkene
with the more highly substituted double bond is the major product). –
• dehydration - elimination of H2O from an alcohol (alkene with the
more highly substituted double bond is the major product). –
• dehydrogenation - elimination of H2 from an alkane. - cracking of
alkanes. ·
Substitution reactions
• * Reactions of HX with alcohols e.g. (CH3)3OH + HBr → (CH3)3Br
+ H 2O
• Reactions where the OH of alcohols are substituted with a halogen e.g.
(CH3)3Br + KOH → (CH3)3OH + KBr
• Two types of saturated structure can be inter-converted by substitution
as shown in the above two reaction equations.
• * Reactions of X2 with alkanes in the presence of light (prior
knowledge from Grade 11).