CHEMISTRY OF ALKANE FAMILY:
HYDROCARBON:
*ACYCLIC HYDROCARBON (ALIPHATIC):
There are two type of acyclic hydrocarbon:
1) Saturated hydrocarbon 2) Unsaturated hydrocarbon
| | |
*CYCLIC HYDROCARBON:
| |
Alicyclic Aromatic
CHEMISTRY OF ALKANES:
*INTRODUCTION
Methane gas is first member of alkane’s family. Its
molecular formula is CH4. It is main component of natural gas. This gas is also
called “MARSH GAS" because it is naturally obtains from marshy places
*METHOD OF PREPARATION:
1) FROM SODIUM ACETATE (SODIUM ETHANOATE):
Methane gas can be prepared by the reaction sodium acetate with
sodium hydroxide in presence of soda lime. This process is called "SODA
LIME PROCESS".
CH3COONa
+ NaOH ---------------> (soda
lime) CH4 +
Na2CO3
2) BY THE REACTION OF METHYL IODIDE:
Methane gas can be prepared by the reaction of methyl iodide
as follow
a) WITH THE HElP OF NASCENT GAS:
When methyl iodide is reacted by nascent gas, methane gas is
formed. In this reaction nascent hydrogen is obtained by reaction of ZINC with
HCl
CH3I + 2[H]
-----------------> (Zn/HCl)
CH4 + HI
b) BY CATALYTIC REACTION:
When methyl iodide is reacted with hydrogen gas in presence
of metallic catalyst like (Pd, Pt or Ni), methane gas is formed
CH3I +
H2 -------------------> (Pd) CH4 + HI
3) FROM GRIGNARD REAGENT:
Methyl magnesium iodide which is a Grignard reagent on
hydrolysis gives methane.
CH3-Mg-I +
H-OH ---------------->
CH4 + Mg (OH) I
CHEMICAL PROPERTIES OF METHANE:
Due to absence of polarity and strong C-H sigma bond,
methane is chemically less reactive under ordinary condition. It can react with
oxygen and halogens etc under specific conditions.
1) COMBUSTION:
When methane burns in presence of oxygen it produces CO2 steam,
and massive amount of energy. This reaction is known as COMBUSTION OF METHANE.
CH4 +
2O2 ---------------------> (Heat) CO2 + 2H20
2) HALOGINATION:
The replacement of one or more hydrogen atom of methane with
halogen atom in presence of sunlight, ultra violet rays or at 400C is called halogenations
reaction.
3) CHLORINATION OF METHANE:
The reaction of methane with chlorine is an example of
substitution reaction and also called chlorination of methane
CH4 + Cl2
----------------------> (sunlight) CH3Cl +
HCl
CH3Cl + Cl2 ----------------------->
CH2Cl2 + HCl
CH2Cl2 + Cl2
------------------------>
CHCL3 + HCl
CHCl3 + Cl2
------------------------>
CCl4 + HCl
CHEMISTRY OF ETHANE:
*INTRODUCTION:
Ethane gas is a second member of alkanes family. Its
molecular formula is C2H6. It is present in natural gas and coal gas.
METHOD OF PREPARATION:
1) FROM GRIGNARD REAGENT:
C2H6 gas can be prepared by the hydrolysis of ethyl magnesium
iodide (GRIGNARD REAGENT)
C2H5-Mg-I + H-OH
--------------------->
C2H6 + Mg-OH-I
2) BY HYDROGENATION OF ETHENE:
When ethene is hydrogenated in presence of nickel at 300C,
ethane gas is found.
CH2=CH2 + H2
--------------------------->
CH3-CH3 (C2H6)
3) BY THE REDUCTION OF ETHYL IODIDE:
When ethyl iodide is reduced in presence by nascent
hydrogen, ethane gas is formed. In this reaction nascent hydrogen is produced
by the reaction of ethyl alcohol with Zn/Cu couple
C2H5-I + 2[H]
-------------------------->(Zn/Cu) C2H6 +
HI
4) WARTZ REACTION:
In wartz reaction, ethane is prepared by the reaction of alkyl
halide with sodium metal in presence of anhydrous ether. In this reaction dry
ether is used to produce sodium metal from moisture.
2CH3Cl + 2Na
----------------------------->(dry ether) C2H6
+ 2NaCl
CHEMICAL PROPERTIES OF ETHANE:
Like methane, ethane is also less reactive compound; ethane
can react with oxygen and halogens.
1) COMBUSTION:
Ethane reacts with oxygen in presence of heat to produced carbon
dioxide gas and water
C2H6
+ 7/2O2 ------------------------------->
(heat) 2CO2 +
3H2O
2) HALOGENATION:
Ethane react with chlorine in presence of sunlight to
produce 1, 2 dichloro ethane
CH3-CH3 + Cl2
------------------------------>(sunlight) CH3-CH2-Cl + HCl
2CH3-CH2-Cl + 2Cl2 -------------------------> CH3-CH-Cl
+ CH2-CH2-Cl + HCl
| |
Cl Cl
|
Terms
|
Meanings
|
Chemical reagent
|
Catalyst / condition
|
||
|
Hydrogenation
|
Addition of H2
|
H2
|
Ni , Pt or Pd / heat
|
||
|
Dehydrogenation
|
Removal of H2
|
-
|
-
|
||
|
Halogenation
|
Addition of X2
|
X2 = Cl2 , Br2
|
-
|
||
|
Dehalogenation
|
Removal of X2
|
Zn
|
Dust / red hot
|
||
|
Hydrohalogenation
|
Addition of H and X
|
HX = HCl , HBr
|
-
|
||
|
Dehydrohalogenation
|
Removal of H and X
|
KOH/NaOH
|
Alcohol
|
||
|
Hydration
|
Addition of H2O
|
H2O
|
H2SO4
|
||
|
Dehydration
|
Removal of H2O
|
-
|
H2SO4 , Al2O3 , H3PO4 + heat
|
||
0 Comments