Prepared by Sir Muzammil Ali
Petroleum is a thick brown or green black liquid obtain from earth. It Derive from Latin word
(Petra; rock) & (Oleum; Oil) therefore commonly called as rock oil. Petroleum is a complex mixture of hydrocarbons and different compounds of sulphur, oxygen and nitrogen in small amounts. Usually it contains alkanes, alkenes, cyclo alkanes, aromatic hydrocarbons etc.
The process of dividing petroleum into fractions with different boiling range volatilities and free from impurities is called refining. Petroleum is refined by fractional distillation .
The process of separating a mixture into a series of fractions of different volatilities by means of distillation is known as fractional distillation.
In the process of fractional distillation, a mixture of different liquids is evaporated followed by condensation. Different liquids are evaporated according to their boiling point and they are collected in different chambers of distillation tower.
Generally crude oil contains compounds having boiling points upto 400
O
C. In this process, crude oil is heated to above 400
O
C in a pipe. Its vapors are allowed to enter into a fractionating tower having different compartment to collect different volatilities. These are now condensed to liquid and are separated.
More than 500 different compounds are obtained in the process of the distillation of petroleum as shown in the table.
Boiling point range
Number of C- atoms
C
1
to C
4
Nature
Below 20
O
C
20
O
C - 60
O
C
60
O
C - 120
O
C
40
O
C - 200
O
C
C
C
C
5
5
to C
6
6
to C
7
to C
10
C
12
to C
18
Natural gas, bottled gas
Petroleum ether
Ligroin
Gasoline
175
O
C - 325
O
C
250
O
C - 400
O
C
Nonvolatile liquids
Nonvolatile solids
C
12
C
20
C
20
- higher
- higher
- higher
Kerosene oil, Jet fuel
Gas oil , fuel oil, diesel oil
Grease, lubricants
Wax, asphalt, tar

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The conversion of straight chain hydrocarbon into branched chain hydrocarbon is
called reforming of petroleum.
By the process of reforming, the octane number of a gasoline is improved. The process of reforming is carried out in the presence of catalyst n-alkanes burn in internal combustion engine with explosion and produce knocking but branched chain hydrocarbons burn smoothly.
Reforming is a process similar to cracking, which converts n-alkanes into branched alkanes.
The octane number of gasoline may also be improved by adding tetraethyl lead (TEL)
Pb(C
2
H
5
)
4 which is a knock inhibitor. But the use of compounds containing lead cause environment pollution.

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A series of organic compounds that have similar structural features but differ from adjacent members by (-
CH
2
) group is referred to as homologous series.
OR
A series of organic compounds that have similar structural features but differ from each other by (-
CH
2
) group (Methylene Group) is referred to as homologous series.
Each member of homologous series is called homolog.
All the members of a homologous series have same structural formula.
Molecular formula of different members of a homologous series differs from previous and next member by
CH
2
.
All the members of series have same type of elements.
All the members of homologous series contain same functional group.
Members of a homologous series can be represented by a general formula.
ALKANE : C n
H
2n
+1
ALKENE : C n
H
2n
ALKYNE : C n
H
2n
-2
ALCOHOL : C n
H
2n
+1--OH
ETHERS : C n
H
2n
O
Where n = number of carbon atoms.
Molecular mass of any two consecutive members differ by 14 units
All the members of a homologous series have same chemical properties due to same functional group.

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The phenomenon in which large molecules of hydrocarbons are thermally decomposed into smaller molecules in the absence of air or oxygen is known as
Cracking or Pyrolysis.
When high molecular mass long chain alkanes are subjected to heat above their boiling point, they are broken down to produce smaller alkanes, alkenes and hydrogen. This thermal decomposition is called "cracking".
Cracking involves splitting of larger alkanes of less volatile in to smaller molecules of high volatility on heating at high temperature and pressure in the presence of catalyst.
Single repeating unit of a large molecule or polymer is called a “monomer”.
The simple and small molecules are known as monomer,
A high molecular mass compound, which consist of repeating units, is called “polymer” large and complex molecules are called polymers
A self-addition reaction in which a number of simple molecules (monomers) are joined to form a very large molecule is called polymerization.
OR
A chemical reaction in which monomers are converted into polymer is called polymerization.
OR
The phenomenon in which simple and small molecules are converted into large and complex molecules is known as Polymerization.
For example: n(C
2
H
4
) (-CH
2
-CH
2
-CH
2
-) or (-CH
2
-CH
2
-) n
monomer polymer
(ethylene) (polyethene)

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Polymerization has been classified the following.
1. Addition Polymerization
2. Condensation Polymerization
The process of Polymerization in which molecules is added into each other is called Addition Polymerization.
When a number of monomers undergo self-combination, resulting substance has a molecular mass many times larger than the monomer, the type of polymerization is known as “Addition polymerization”.
In presence of traces of oxygen when is heated at about 200ºC under 100 atm pressure, then
Polymerization takes place. As a result, monomers add together to form polymer i.e. Polyethene or
Polythene.
The process of Polymerization in which removal of water molecule takes place with the formation of polymer is called Condensation Polymerization.
Condensation polymers are formed by the combination of monomers with the elimination of simple molecules such as H
2
O or CH
3
OH.
Bakelite Plastic is the Polymer that is obtained by the polymerization of Phenol and formaldehyde. During this process removal of water molecule takes place.

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An atom or group of atoms or radical which is responsible for the entire chemical properties of an organic compound is called a functional group.
OR
An atom or group of atoms in a molecule that gives the molecule its characteristic chemical properties is called a functional group.
OR
Active part of an organic compound which takes part in chemical reaction is always a functional group.
OR
A functional group is a set of atoms bonded together in a specific way
OR
Functional groups largely define the chemical and physical properties of the compound (Molecules with similar functional groups “behave” in a similar fashion)
Generally an organic compound is composed of two parts.
 Hydrocarbon part
 Active part
Hydrocarbon part of an organic compound is chemically inert and the other part which is active is called functional group.

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❍
❍
–
–
–
–
2
4
3
8
2
4
3
6
2
2
3
4
2
5
3
2
5
2
5
2
3
2
5
3
3
3
3
3
3
2
5

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Organic compounds are divided on to two major categories:
1)
Open Chain Compounds or Acyclic Compounds
2)
Closed Chain Compounds or Cyclic Compounds

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Organic compounds which have open chain skeleton are known as aliphatic compounds.
For example:
Organic compounds containing closed ring are known as cyclic compounds.
Cyclo butane

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I.
When ring of compound consists of carbon atoms only, the compound is said
to be "homocyclic or Carbocyclic compound".
II.
When ring of compound consist of carbon as well as any other element, the compound is said to be "heterocyclic compounds".
OR
Cyclic compounds which contain at least one atom of another element in
addition to carbon in the ring are referred to as "heterocyclic compounds"

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Homocyclic compounds are divided in to two types.
a.
Alicyclic compounds.
b.
Aromatic compounds.
Alicyclic compounds.
Homocyclic compounds which resemble aliphatic compounds and do not contain benzene ring are termed as "Alicyclic compounds".
Aromatic compounds.
Homocyclic compounds containing benzene ring are known as "Aromatic compounds".

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If a carbon atom attached to functional group is directly attached to only one carbon atom, then it is said to be a "Primary carbon atom" or "1 o C-atom".
If a carbon attached to functional group is directly attached to the two C-atoms, then it is said to be "Secondary carbon atom" or 2 o C-atom".
If the carbon atom that is attached to a functional group is directly attached to three Catoms, then it is said to be a "Tertiary carbon atom" or "3 o C-atom".
Organic compounds containing Amino (NH2) functional group are known as
"Amines".
CH
3
-NH
2
methyl amine
C
2
H
5
-NH
2
ethyl amine

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Hydrocarbons in which all the valencies of carbon atoms are fully utilized by single covalent bonds are known as saturated hydrocarbons.
They are saturated in respect to chemical combination with the other compounds and elements.
Saturated hydrocarbons are chemically inert to some extent.
Alkanes (methane, ethane, propane etc.)
CHARACTERISTIC REACTIONS:
Characteristic reactions of saturated hydrocarbons are "substitution reaction".
ADDITION REACTIONS:
They do not undergo addition reactions in any circumstances.
Hydrocarbons in which all the valencies of carbon atoms are not fully utilized by single covalent bonds are known as "unsaturated hydrocarbons".
They contain at least one double or triple bond in their structure.
Alkenes, Alkynes
CH2=CH2 ,
Reactivity:
They are very reactive hydrocarbons. Their high reactivity is due to the presence of pi-bond in their structure.
CHARACTERISTIC REACTIONS:
Their characteristic reactions are addition reactions.
SUBSTITUTION REACTIONS:
Unsaturated hydrocarbons (alkynes) may undergo substitution reactions.

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Alkanes are open chain saturated hydrocarbons (aliphatic hydrocarbons) in which all carbon atoms are bonded to each other by single covalent bond.
Each carbon is tetrahedrally surrounded by H-atoms. Since all the valencies of carbon atoms are fully utilized by sigma bond with H-atoms therefore, they are also known as "Saturated
Hydrocarbons".
where,
n=number of C-atoms methane , ethane, propane , butane etc.
Characteristic reactions of alkanes are "substitution reactions".
Alkanes are relatively chemically inert to some extent that's why they are also called "PARAFFINS".

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Alkenes are open chain unsaturated hydrocarbons in which a carbon-carbon bond is a double covalent bond.
where,
n=number of C-atoms ethene, propene etc.
Characteristic reactions of alkenes are "Addition reactions".
They are very reactive organic compounds due to the presence of PI-BOND. They are also known as "OLEFINS”.
Alkynes are open chain an unsaturated hydrocarbon in which one bond between any two carbon atoms is a triple covalent bond.
where,
n=number of C-atoms ethyne, propyne etc.
Characteristic reactions of alkenes are "Addition reactions".
Alkynes are more unsaturated hydrocarbons than alkenes. They are also very reactive compounds.

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Molecular formula = CH
4
Molecular mass = 16
Empirical formula = CH
4
Empirical formula mass = 16
State: Gas at room temperature.
Occurrence: marsh, stagnant ponds.
It is the major constituent of natural gas. Natural gas contains 94.6% methane.
Methane molecule consists of one carbon and four hydrogen atoms (CH
4
).
In methane C-atom is Sp
3
-hybridized. One s-orbital and three p-orbitals (2p x
,2p y
,2p z
) of carbon atom undergo Sp
3
-hybridization to produce four Sp
3
-hybrid orbitals. These Sp
3
hybrid orbitals are 109.5
o a part.
Each Sp
3
-hybrid orbital overlaps 1s-orbital of H-atoms. In this way four

-bonds are produced between C and four H-atoms.
Methane molecule is tetrahedral in structure in which carbon is central atom and four Hatoms are surrounding it in three-dimensions.
HCH-bond angles are 109.5
o .
All C-H bonds are 1.09A
o .

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Methane can be prepared by the hydrolysis of "Methyl Magnesium Iodide".

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Combustion of methane is an exothermic reaction in which a large amount of energy is liberated. Due to this property, methane is used as a domestic and industrial fuel.
CH
4
+ 2O
2
 CO
2
+ 2H
2
O
Replacement of halogen atom with H-atom of an organic compound is called Halogenation.
It is a substitution reaction.
CH
4
+ Cl
2

CH
3
Cl + Cl
2

CH
2
Cl
2
+ Cl
2

CHCl
3
+ Cl
2

CH
3
Cl + HCl (chloro methane)
CH
2
Cl
2
+HCl (dichloro methane)
CHCl
3
+ HCl (chloroform)
CCl
4
+HCl (carbon tetra chloride)
It is a photochemical reaction.
In the presence of sunlight Cl
2
molecule undergoes homolytic fission to produce Clfree radical.
Cl-Cl  Cl o + Cl o (free radical)
Chlorine free radical attacks methane molecule to produce methyl free radical.
CH
4
+ Cl o 
CH3 o + Cl
2

CH
3 o
CH
3
+ HCl
Cl + HCl
This reaction comes to halt when any two free radicals combine.
Cl o + Cl o 
CH
3 o + Cl o 
CH
3 o + CH
3 o 
Cl
2
CH
3
-Cl
CH
3
-CH
3
Since it is a chain reaction, therefore, it gives a mixture of different compounds.

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 Methane is a colorless, odourless and non-poisonous gas.
 Melting point = -182.5
o C.
 Boiling point = -169.5
o C.
 Its molecule is symmetrical.
 It is lighter than air.
 Domestic and industrial fuel.

Shoe polish.

Printing ink.
 Tyre manufacturing.

Manufacture of methyl alcohol.
Molecular formula = C
2
H
6
Molecular mass = 30
Empirical formula = CH
3
Empirical formula mass = 15
State: Gas at room temperature.
Occurrence: Ethane occurs along with methane in natural gas and gases from oilwells. It is also present in coal gas in very small quantity.

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Ethane molecule consists of two carbon atoms and six H-atoms (C
2
H
6
).
In ethane each C-atom is Sp and three p-orbitals (p x
, p
3 -hybridized containing four Sp 3 -hybrid orbitals. One s-orbital y
, p z
) undergo Sp orbitals for each carbon atom.
3 -hybridization to produce four Sp 3 -hybrid
Out of four Sp 3 -hybrid orbitals one Sp 3 -hybrid orbital of one C-atom overlaps with one sorbital of H-atom to produce three sigma bond and the last overlaps with one Sp other C-atom to produce a sigma bond between two C-atoms.
3 -orbital of
Ethane molecule is arranged in tetrahedral geometry in which central carbon atoms are surrounded by H-atoms in three dimensions
HCH bond angle is 109.5o.
C-H bond length is 1.09A
o and C-C bond length is 1.54Ao.

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2CH
3
I + 2Na  C
2
H
6
+2NaI
Ethane may be obtained by the hydrolysis of ethyl magnesium iodide.
C
2
H
5
-Mg-I + HOH C
2
H
6
+ Mg-OH-I
C
2
H
5
-I + 2[H] C
2
H
6
+ HI
C
2
H
5
-I + H
2
C
2
H
6
+ HI
Ethane burns in air or oxygen with a non-luminous flame to produce carbon dioxide and water. It is an exothermic Reaction
2C
2
H
6
+ 7O
2
4CO
2
+ 6H
2
O + Heat
Replacement of halogen with H-atom of an organic compound is called Halogenation. It is a substitution reaction.
C
2
H
6
+ Cl
2
C
2
H
5
Cl C
2
H
4
Cl
2
+ Cl-CH
2
-CH
2
-Cl

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It is colorless gas.
Its boiling point is -89 o C.
It is sparingly soluble in water.
Molecular formula = C
2
H
4
Empirical formula = CH
2
Molecular mass = 28
Empirical formula mass = 14
Homologous series = alkene
Ethene molecule consists of two carbon atoms and four H-atoms i.e. CH2=CH2
In ethene molecule each C-atom is Sp2-hybridized. Due to Sp2-hybridization each Catom generates three Sp2-hybrid orbitals. In this way there exist six Sp2-hybrid orbital. These Sp
2
-orbital are arranged in trigonal order and 120 o apart. Remaining
'2p z
' unhybrid orbital of carbon atom are placed perpendicular to the plane of Sp2orbitals.
One Sp2-hybrid orbital of C-atom overlaps with One Sp2-hybrid orbital of second Catom to produce one sigma bond between two carbon atoms. Remaining two Sp2-

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' orbitals of two C-atoms are un-hybridized and make parallel overlapping to produce pi-bond as shown below:
C=C bond length is 1.34A.
C-H bond length is 1.09A.

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When vicinal dihalide is heated with zinc dust, two halide atoms are removed from the compound and ethene is formed.
CH
2
=CH
2
+ ZnCl
2
CH
2
-CH
2
+ Zn
| |
Cl Cl
Under control conditions ethyne adds two H-atoms to form ethene in the presence of Nickel
(Ni) at 200oC.
+ H
2
When alkyl halide (ethyl chloride) is treated with alcoholic KOH,  -elimination takes place and ethene is obtained.
CH
3
-CH
2
Cl + KOH CH
2
=CH
2
+ KCl + H
2
O
When ethyl alcohol is heated with conc.H
2
SO
4
at 170 o C, dehydration of alcohol takes place and ethene is formed.
C
2
H
5
OH C
2
H
4
+ H
2
O
OR
Ethyl alcohol may also be converted into ethene by passing vapours of ethyl alcohol over catalyst (Al
2
O
3
,H
3
PO
4
/Al
2
O
3
).The reaction is carried out at 350C in the presence of Al
2
O
3
and at 250C when H
3
PO
4
/Al
2
O
3
is used.
C
2
H
5
OH C
2
H
4
+ H
2
O
Addition of chlorine:
CH
2
=CH
2
+ Cl
2
Addition of bromine:
CH
2
=CH
2
+Br
2
Addition of iodine:
CH
2
=CH
2
+ I
2
Order of reactivity:
CH
2
Cl-CH
2
Cl (1,2-dichloroethane)
CH
2
Br-CH
2
Br (1,2-dibromoethane)
CH
2
I-CH
2
I (1,2-diiodoethane)

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Cl
2
> Br
2
> I
2
ADDITION OF HYDROGEN:
CH
3
-CH
3
CH
2
=CH
2
+ H
2
ADDITION OF H2SO4:
CH
2
=CH
2
+ H
2
SO
4
ADDITION OF H2O:
CH2=CH2 + HOH
ADDITION OF HCl:
CH
3
-CH
2
-HSO
4
CH3-CH2-OH
CH2=CH2 + HCl
ADDITION OF HBr:
CH2=CH2 + HBr
ADDITION OF HI:
CH3-CH2-Cl
CH3-CH2-Br
CH2=CH2 + HI CH3+CH2-I
ADDITION OF HYPOHALOUS ACID:
CH2=CH2 + HOCl OH-CH2-CH2-Cl (Ethane chlorohydrin)
REACTION WITH CHLORINE WATER:
When Cl2 is mixed with water, two molecules of acids are formed.
Cl2 + H2O
CH2=CH2 + HCl
HCl + HOCl
CH2=CH2 + HOCl
COMBUSTION REACTION:
CH3-CH2-Cl
OH- CH2-CH2-Cl
CH2=CH2 + 3O2
OXIDATION REACTION:
2CO2 + 2H2O
When ethene is treated with KMnO4 solution, purple colour of KMnO4 disappears due to deformation of a colourless compound "Ethylene Glycol".
CH2=CH2 + H2O +[O]
FORMATION OF MUSTARD GAS:
OH-CH2-CH2-OH
 ,  -Dichloroethyl Sulphide is commonly known as "Mustard gas". It is a very poisonous gas. It can produce blisters on skin.
2CH2=CH2 + S2Cl2
POLYMERIZATION:
Cl-CH2-CH2-S-CH2-CH2-Cl + S
n(CH2=CH2) n(-CH2-CH2-)