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LIMONENE
MYRCENE
LYCOPENE
BETA CAROTENE
CARYOPHYLLENE
GERANIOL
MENTHOL
ZINGIBERENE
UNSATURATED
HYDROCARBON
UNSATURATED HYDROCARBON
 Contain one or more carbon –
carbon double, triple bonds and
benzene ring in their structures.
 The term “ UNSATURATION “
shows that there are fewer
hydrogens attached to carbon than
in ALKANE.
3 family
 ALKENE – An unsaturated hydrocarbon
that contains one or more carbon – carbon
double bonds.
 ALKYNES – An unsaturated hydrocarbon
that contains one or more carbon – carbon
triple bonds.
 AROMATIC – Organic compounds that
contains the characteristics of benzene &
benzene ring in its structure.
Physical Properties
 The physical properties of unsaturated
hydrocarbons are very similar to those of the
corresponding saturated compounds. They
are very slightly soluble in water.
 Except for aromatic compounds,
unsaturated hydrocarbons are highly
reactive and undergo addition reactions to
their multiple bonds. Typical reagents
added are hydrogen halides, water, sulfuric
acid, elemental halogens and alcohols.
ALKENES
Nomenclature
of
ALKENES
RULES ON NAMING ALKENES
RULE 1 : Number the
carbon chain to give the
lowest number to the
double bond.
(be sure to use the longest carbon
chain containing the double bond for
the parent chain )
ethene
1
1
1 - propene
3
2
2
3
2 - butene
4
CH2
1║
CH3 – CH2 – C – CH2 – CH3
4
3
2
2 – ethyl – 1 – butene
CH3 – CH – CH2 – C – CH2 – CH2 – CH3
5│
3HC2HC
7
6
4
3║
CH – C H3
2
1
5 – methyl – 3 – propyl – 2 – heptene
RULES ON NAMING ALKENES
RULE 2 : If there are
multiple double bonds in a
structure we use the
prefixes such as di, tri,
tetra, penta, and so
on……………….
CH2 ═ C
–
C
═
C
–
CH
3
2
3
4
5
│
1
3HC
│
│
CH3 CH3
2,3,4 – trimethyl – 1,3 – pentadiene
3HC
CH3
CH3
│
│
│
CH2 ═ C – CH2 – C ═ C – CH – C ═ CH2
8
7
6
│5
CH3CH2
4
│3
2
1
CH2CH3
3,5 – diethyl – 2,4,7 – trimethyl – 1,4,7 – octatriene
RULES ON NAMING ALKENES
RULE 3 : If an ALKENE
is a ring structure, place
the prefix “cyclo” in front
of the ALKENE name.
CYCLOPROPENE
1,3,5,7 – cyclooctatetraene
1,4 – cyclohexadiene
RULES ON NAMING ALKENES
RULE 4 : If CYCLOALKENE
has a side groups or chain, the
double bond is numbered as
carbon 1 & 2 in the direction
around the ring that gives the
lowest numbers to the first
branch…….
CH2CH3
3 – ethyl – 4 – methyl – 1 – cyclobutene
Br
CH3
Br
1,2,4 – tribromo – 1,4 – cyclohexadiene
Br
1 – chloro – 3,3 – difluoro – 1 - cyclopropene
F
Cl
F
Physical Properties
 The physical properties of alkenes
are comparable with ALKANES.
The PHYSICAL STATE depends on
MOLECULAR MASS.
 The simplest alkenes, ethylene,
propylene and butylene are gases.
 Linear alkenes of approximately five
to sixteen carbons are liquids, and
higher alkenes are waxy solids.
Chemical Properties
 Alkenes are relatively stable compounds, but are
more reactive than alkanes. This is compatible
with the idea that the carbon-carbon double bond
in alkenes is stronger than the carbon-carbon
single bond in alkanes, however, as the majority
of the reactions of alkenes involve the rupture of
this bond to form two new single bonds.
 A double bond is not as strong as a single bond,
so it is more easily broken. This means that the
alkenes are more chemically reactive than the
alkanes.
Reactions
Addition Reaction
 Is a type of chemical reaction in
which a compound adds to a
multiple bond.
 In the case of addition reaction
take place in ALKENES, one
bond in the double bond is broken
in order to form new bonds.
Types of Addition Reaction





Halogenation
Hydrogenation
Hydrohalogenation
Hydration
Polymerization
Halogenation
 Is an addition reaction wherein
unsaturated hydrocarbon
specifically ALKENE reacts with
halogens such as chlorine,
bromine, fluorine, and iodine that
produce haloalkane as a product.
General Formula of :
 Halogenation Reaction:
Alkene
+ Halogen ------------→ Haloalkane
Example :
Cl – Cl
CH2 = CH2 + Cl2
ethene
------------→
CH2Cl – CH2Cl
1,2 - dichloroethane
Mechanism
F–F
+ F2 ----------→
CH3 – CH = CH2
F
F
│
│
CH3 – CH – CH2
1,2 - difluoropropane
Industrial Application
Hydrogenation
 Is an addition reaction wherein
double bond adds hydrogen in
the presence of transition metal
catalyst such as platinum (Pt)
and nickel (Ni) that yield to
saturated hydrocarbon as
product.
General Formula of :
 Hydrogenation Reaction
Pt/Ni
Alkene + Hydrogen ------------→ Alkane
Example:
CH2 = CH2
ethene
H–H
Pt/Ni
+ H2 ------------→ CH3 – CH3
ethane
Mechanism
Pt
CH3 – CH = CH2
+
H2
-----------------→
H–H
CH3 – CH2 – CH3
PROPANE
Industrial Application
HYDROHALOGENATION
 Is an addition reaction wherein
hydrogen halides such as hydrogen
chloride (HCl), hydrogen bromide
(HBr), hydrogen fluoride (HF) and
hydrogen iodide (HI) is added to
unsaturated sites that yield to
halogenated hydrocarbon as product.
General Formula of :
 HYDROHALOGENATION REACTION
Alkene + Hydrogen Halides -----------→ Haloalkane
Example:
CH2 = CH2
ethene
H – Cl
+ HCl -----------→ CH3 – CH2Cl
1 - chloroethane
Mechanism
H – Cl
CH2 = CH2 +
----------------→
ethene
Cl
│
H
│
CH2 – CH2
1 - chloroethane
Conditions under
HYDROHALOGENATION REACTION
 2 TYPES OF ALKENE STRUCTURE
 SYMMETRICAL – Is an ALKENE structure
having the same number of hydrogen atoms
attached to both sides of the double bond.
 UNSYMMETRICAL – Is an ALKENE structure
having different numbers of hydrogen atoms
attached to both sides of the double bond
Markovnikov ‘s Rule
 “ the rich get richer “
 If the two carbon atoms at the
double bond are linked to a
different number of hydrogen
atoms, the halogen will attach at
the carbon with least number of
hydrogen and hydrogen will attach
at the carbon with more hydrogen
attached to it.
Vladimir Markovnikov
 Russian chemist
 College Professor
 University of Kazan in St.
Petersburg
 Director of the Chemistry
Institute
 1869
 He gave rise to rule for
predicting w/c product
will be exclusively or
predominantly formed.
Actual Reaction
CH2 = CH – CH3
Br
│
+
H
H
│
│
CH2 – CH – CH3
1
H – Br
2
3
1 - bromopropane
10 %
or
---------------→
Br
│
CH2 – CH – CH3
1
2
3
2 - bromopropane
90 %
Examples
CH3 – CH = CH – CH3
H
│
+ H – Cl
Cl
│
-----------→
2 - chlorobutane
1
CH3 – CH – CH – CH3
4
3
CH3 – CH2 – CH = CH2
2
+ H – Cl
Cl
H 2 - chlorobutane
│
│
2
1
CH3 – CH2 – CH – CH2
4
3
-----------→
90 %
Industrial Application
HYDRATION
 Is an addition reaction in
which the components of
water, H – and OH, bond to
the carbon – carbon double
bond in the presence of strong
acid catalyst such as sulfuric
acid to form an alcohol.
General Formula of :
 HYDRATION REACTION
Alkene
H2SO4
Water ------------→
+
Alcohol
Example:
CH2 = CH2 +
ethene
H2SO4
H – O H -----------→ CH3 – CH2OH
ethyl alcohol
Mechanism
CH3 – CH = CH2
1 - propene
+
H – OH
OH
│
H
│
CH3 – CH – CH2
2 - propanol
(Isopropyl alcohol)
H2SO4
-----------→
Industrial Application
POLYMERIZATION
POLYMERIZATION
 A REACTION THAT PRODUCES A
POLYMER………
 Polymerization - Is the single most
important reaction of alkenes it is an
economically important reaction which
yields polymers of high industrial value,
such as the plastics polyethylene and
polypropylene
Addition
Polymerization
A reaction in which
monomer units are
joined together to form a
polymer without loss of
atoms.

MONOMER
 From the Greek, meaning single
part; a small building block from
which a polymer is derived.
 single part; (mono + meros).
 The starting material that
becomes the repeating units of
polymer.
Monomer Formula
Common Name
Polymer Name &
Common Uses
CH2 ═ CH2
ethylene
Polyethylene, polythene; containers &
packaging materials.
CH2 ═ CHCH3
propylene
Polypropylene, herculon; textile and
carpet fibers.
CH2 ═ CHCl
Vinyl chloride
Poly (vinyl chloride), PVC;
construction tubing.
CH2 ═ CCl2
1,1 dichloroethylene
Poly (1,1 – dichloroethylene), Saran;
food packaging.
CH2 ═ CHCN
acrylonitrile
Polyacrylonitrile, Orlon; acrylics and
acrylates.
CF2 ═ CF2
Tetrafluoroethylene
Polytetrafluoroethylene, Teflon;
nonstick coatings.
CH2 ═ CHC6H5
styrene
Polystyrene, Stryrofoam; insulating
materials.
CH2 ═ CHCO2CH2CH3
Ethyl acrylate
Poly (ethyl acrylate); latex paint.
CH2 ═ CCO2CH3
│
CH3
Methy methacrylate
Poly (methyl methacrylate), Lucite,
Plexiglass; glass substitute.
POLYMER
 From Greek, meaning many
parts; a large molecule built up
from bonding together of smaller
units called monomer.
 Many part (poly + meros).
 A very large molecule made up
of repeating units.
2 Types of Polymer
 ADDITION POLYMER – A polymer
formed by the linking together of many
alkene molecules through addition
reactions.
 COPOLYMER – An addition polymer
formed by the reaction of two different
monomers.
3 steps in
POLYMERIZATION

Step 1 : Chain Initiation – formation
of radicals from non – radical molecules.
Example :
NOTE: LDPE (500°C/1000 atm & Peroxides catalyst)
TiCl3/Al(CH2 – CH3)3
In – CH2 – CH2·
In· + CH2 ═ CH2 ------→
60°C/20atm
Alkyl radical
Step 2 : Chain Propagation
 Is a reaction of a radical and a molecule of
monomer.
 Propagation steps generally repeat over and over
(propagate) with the radical formed in one step
reacting with a monomer to produce a new radical,
and so on.
 Chain propagation steps can continue until all
starting materials are consumed.
 The number of times a cycle of chain propagation
steps repeats is called CHAIN LENGTH.
Example
In – CH2 CH2·
radical
------→
+
CH2 ═ CH2
monomer
In – CH2CH2CH2CH2·
Chain length
Step 3 : Chain Termination
 The characteristic feature of a chain
termination step is coupling of radicals
to form a compound with an even
number of electrons.
 Note : polymerization of ethylene, chain
lengthening reaction occur at a very rapid
rate, often as fast as thousand of addition
per second, depending on the experimental
conditions.
Example :
~ CH2CH2·
+
·CH2CH2 ~
--------→ ~ CH2CH2 – CH2 CH2 ~
Polymer (Polyethylene)
PET Polyethylene
Terephthalate
 Two-liter
beverage
bottles,
mouthwash
bottles, boilin-bag
pouches.
1
HDPE High Density
Polyethylene
 Milk jugs,
trash bags,
detergent
bottles.
PVC Polyvinyl Chloride
 Cooking oil
bottles,
packaging
around
meat, pipes,
plastic tiles.
Low Density Polyethylene
 Grocery
bags,
produce
bags, food
wrap, bread
bags.
PP Polypropylene
 Yogurt
containers,
shampoo
bottles,
straws,
margarine
tubs, diapers.
PS Polystyrene
 Hot beverage
cups, takehome boxes,
egg cartons,
meat trays,
cd cases.
OTHER
 All other types
of plastics or
packaging
made from
more than one
type of plastic.