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CARBON AND ITS COMPOUNDS
Carbon Compounds
The compounds of carbon are called carbon compounds.
Carbon forms a large number of compounds. Today
approximately 3 millions of carbon compounds containing a
variety of other elements are known. Many of these carbon
compounds are being used in our daily life e.g. soaps,
detergents, fabrics, plastics, medicines, dyes and food
preservators etc.
Types Of Covalent Bonds
1. Single Covalent Bond
2. Double Covalent Bond
3. Triple Covalent Bond
Existence Of Carbon
The amount of carbon present in the earth crust and
atmosphere is quite meager. The earth’s crust has 0.02 %
carbon in the form of minerals like carbonates, bicarbonates,
coal and petroleum. The atmosphere has 0.03 % of carbon in
the form of carbon dioxide.
1. Single Covalent Bond
When only one pair of electrons is shared between two
combining atoms a single bond is formed. In this each atom
shares one electron. A single bond is denoted by single dash(-)
between the two atoms, e.g. H 2 , Cl 2 , H 2 O, NH 3 , CH 4 , CCl 4
etc.
Types Of Carbon Compounds
Carbon mainly forms two types of compounds:
1. Organic Compounds
The compounds of carbon (except the oxides, carbonates,
hydrogen carbonates and carbides of carbon) are called
organic compounds.
2. Inorganic Compounds
The oxides, carbonates, hydrogen carbonates and carbides of
carbon are called inorganic carbon compounds.
Hydrocarbons
Compounds of carbon with hydrogen are called hydrocarbons.
Bonding In Carbon- The Covalent Bond
The atomic number of carbon is 6 and its electronic
configuration is 2,4, i.e., it has four electrons in its outermost
shell and needs to gain or loose four electrons to attain noble
gas configuration. But it is not possible for carbon to gain or to
loose four electrons. It is because: (i) If it gains four electrons forming C4- anion, it would be
difficult for the nucleus with six protons to hold on to ten
electrons, that is four extra electrons.
(ii) If it looses four electrons forming C4+ cation, it would
require a large amount of energy to remove four electrons
leaving behind a carbon cation with six protons in its
nucleus holding on to just two electrons.
Carbon overcomes its problem by sharing its valence electrons
with other atoms of carbon or with other atoms of other
elements. The shared electrons belong to the outer shells of
both the atoms and lead to both atoms attaining the noble gas
configuration.
Covalent Bond
A covalent bond is the bond between two atoms which is
formed by the sharing of electrons between the two atoms.
The sharing of electrons takes place in such a way that each
atom in the resulting molecule gets the stable electron
arrangement of an inert gas. When ever a non – metal
reacts with another non – metal, sharing of electrons
takes place between their atoms and a covalent bond is
formed. Covalently bonded molecules are seen to have a
strong bond within the molecule but intermolecular forces are
small. This gives rise to low melting and boiling points of these
compounds. And covalent compounds are generally poor
conductors of electricity.
Formation Of Cl 2 Molecule
Chlorine is a monovalent atom. It has 7 electrons in the
outermost shell and to become stable it needs one
electron. Therefore two chlorine atoms share their
electrons to form a diatomic molecule of chlorine Cl 2 . This
allows each chlorine atom to attain noble gas
configuration of argon.
Other examples are:
(i) HCl (Hydrogen chloride)
(ii) H 2 O (Water)
(iii) CH 4 (Methane)
(iv) C 2 H 6 (Ethane)
2. Double Covalent Bond
When two pairs of electrons are shared between two
combining atoms, a double bond is formed. In a double bond
each atom shares two electrons. A double bond is denoted by
double dash (=) e.g. O 2 , CO 2 , C 2 H 4
Formation Of CO 2 Molecule
Carbon is a tetravalent atom and oxygen is a divalent
atom. Carbon needs four more electrons to achieve
nearest noble gas configuration and oxygen needs two
more electrons to achieve nearest noble gas
configuration. So one carbon atom combines with two
oxygen atoms and each oxygen atom shares two
electrons with one carbon atom. Carbon shares its four
electrons i.e., two electrons with each oxygen atom. The
two electrons contributed by each oxygen element and
four by carbon two with each oxygen gives rise to a pair
of two shared pairs of electrons and hence a double bond
is formed.
Other examples are: (i) O 2 (Oxygen Molecule)
(ii) C 2 H 4 Ethane
2. Triple Covalent Bond
When three pairs of electrons are shared between two
combining atoms, a triple bond is formed. In a triple bond
each element shares three electrons. A triple bond is denoted
by triple dash ( ≡ ) e.g. N 2 , C 2 H 2 .
Formation of N2 molecule
Nitrogen has the atomic number 7. It has five electrons in its
outermost shell. In order to attain an octet each nitrogen atom
in a molecule of nitrogen contributes three electrons giving
rise to three shared pairs of electrons. This is said to constitute
a triple bond between two nitrogen atoms.
C 2 H 2 Ethene
Hydrocarbons
Compounds of carbon and hydrogen are called hydrocarbons.
The hydrocarbons along with carbon and hydrogen may also
include halogens, oxygen, sulphur and phosphorous etc..
Types Of Hydrocarbons
1. Saturated Hydrocarbons
The hydrocarbons in which the carbon atoms are linked with a
single bond are saturated hydrocarbons. To form these, the
first step is to link the carbon atoms together with a single
bond and then use the hydrogen atoms to satisfy the
remaining valencies of carbon. The saturated hydrocarbons
are generally called alkanes. Alkanes are solid at room
temperature and the most stable hydrocarbons among all or
we can say that these compounds are generally not very
reactive.
2. Unsaturated Hydrocarbons
The hydrocarbons in which the carbon atoms are linked with a
double or triple bond are called unsaturated hydrocarbons. To
form these, the first step is to link the carbon atoms together
with a double or triple bond and then use the hydrogen atoms
to satisfy the remaining valencies of carbon. The unsaturated
hydrocarbons are generally called alkenes or alkynes. Alkenes
and alkynes are unstable hydrocarbons and liquid at room
temperature. The unsaturated hydrocarbons are reactive in
nature.
Homologous Series Of Hydrocarbons
A series of compounds in which the same functional group
substitutes for hydrogen in a carbon chain is called a
homologous series. In a homologous series each successive
member of the series differs with the previous member by a
CH 2 group and 14 u by mass.
1. Catenation
Carbon has the unique ability to form bonds with other atoms
of carbon. This ability of self combination of carbon is called
catenation. These compounds may have long chains of
carbon, branched chains of carbon and or even carbon atoms
arranged in the rings. In addition carbon atoms may be linked
by single, double and triple bonds.
Characteristic Of Homologous Series
(i) All the members of homologous series can be represented
by the same general formula.
(ii) The molecular formulae of any two successive adjacent
members of a homologous series differ by a CH 2 group.
(iii) The molecular masses of any two successive members of
a homologous series differ by 14 u.
(iv) All the members of a homologous series have similar
chemical properties.
(v) All the members of a homologous series have the same
functional group.
(vi) The members of a homologous series show a gradation in
the physical properties as the molecular mass increases.
For example the melting and boiling points increases with
the increase in the atomic mass.
2. Tetravalency
Since carbon has a valency of four, it is capable of bonding
with four other atoms of carbon or atoms of some other
monovalent element.
Writing Formulae Of Hydrocarbons
(i) Chemical or molecular formula
(ii) Condensed formula
(iii) Structural formula
Why The Covalent Compounds Formed By Carbon Are
Stable As Compared To The Covalent Compounds
Formed By Other Elements?
Covalent compounds formed by carbon are stable in nature
due to small size of the carbon atom. Due to this the nucleus
has a strong hold on the shared pairs of electrons.
Chemical Formula Or Molecular Formula
The chemical or molecular formula consists of the total
number of atoms of the elements present in the hydrocarbon.
Versatile Nature Of Carbon
Why Carbon Forms A Large Numbers Of Compounds?
It is due to the versatile nature of carbon it can form large
number of compounds. This versatile nature is due to two
peculiar properties of carbon which are:-
Example
Methane CH 4 , Ethane C 2 H 6 , Propane C 3 H 6
Condensed Formula
The condensed formula shows the total number of hydrogen
atoms attached to each carbon atom in a compound.
Example
Ethane CH 3 CH 3 , Propane CH 3 CH 2 CH 3
Structures Of Hydrocarbons
The hydrocarbons exist in the following structures:
(i) Straight chain structures
Propyne
Butyne
Ring Structures
(ii) Ring or Cyclic structures
Cyclopentane
Cyclohexane
(iii) Branched structures
Benzene
Nomenclature Of Carbon Compounds
(i)
(ii)
(iii)
(iv)
(v)
Identify the number of carbon atoms in carbon
compound. Name the carbon compounds according to the
number of carbon atoms and the type of bond present.
If the structure has branched chain, identify the longest
chain and then identify the number of carbon atoms and
name it.
Identify the longest chain. Then number the carbon atoms
in such a fashion that the functional group; if any; would
come at the lowest number. To identify the lowest
number the numbering should be done from both sides of
the parent chain.
In case of a functional group present, write the prefix or
suffix of the functional group accordingly. Then write the
name of the parent compound.
The number of the carbon atom to which the functional
group or the branch is attached is to be written before the
name of the parent chain with a hyphen in between.
Straight Chain Structures
(i) Alkanes
Propane
(vi) Branched Structures
Isomers
Isomers are the chemical compounds having same
chemical or molecular formula but different structural
formula. The isomers have different chemical properties.
Alkanes
(i) Isomers of Butane
Butane
2- methyl propane
(ii) Isomers Of Pentane
Butane
(ii) Alkenes
Pentane
Ethene
(iii) Alkynes
Butene
2- methyl butane
5.
||
Carboxylic Acid Group − COH or − CO − OH
O
||
Ester Group − COOR or
− C − OR
6.
Halogen Group
4.
− X (X can be Cl, Br or I)
1. Alcoholic Group – OH
2,2 – dimethyl propane
Alkenes
(i) Isomers of Butene
1-Butene
2-Butene
The alcoholic group is made up of oxygen atom and hydrogen
atom joined together. The alcoholic group is also known as
alcohol or hydroxyl group. The compounds containing alcoholic
group are known as alcohols.
General Formula Of Alcohols
R – OH
Where
R
Alkyl Group
–OH
Functional Group
Alcohols are derivatives of hydrocarbons in which hydrogen
atoms in the parent hydrocarbon have been replaced by one
or more hydroxyl groups (– OH).
Homologous Series Of Alcohols
Alcohols form homologous series.
General Formula For Homologous Series Of Alcohols
C n H 2n+1 – OH
Where n is the number of carbon atoms in one molecule of
alcohol.
The first five members of the homologous series of alcohols
are given below: -
Alkynes
(i) Isomers Of Butyne
1-Butyne
Functional Groups
2-Butyne
An atom or a group of atoms which makes a carbon
compound reactive and decides its properties is called a
functional group. Replacing part of a hydrocarbon with
functional group changes the structure, properties and uses of
a compound. Some of the important functional groups are as
follows:1. Alcoholic Group − OH
O
||
2. Aldehydic Group − CHO or − C − H
O
||
3. Ketonic Group –C=O– or − C − or − CO −
O
O
||
||
an aldehydic group is –C– H and a ketonic group is – C –. We
can see that both aldehydes and ketones have a common
O
O
||
||
–C – group. The –C – group, in general, is called a carbonyl
group.
O
Common Name
Methyl Alcohol
IUPAC Name
Methanol
Alcohol Formula
CH 3 OH
Ethyl Alcohol
Ethanol
C 2 H 5 OH
Propyl Alcohol
Propanol
C 3 H 7 OH
Butyl Alcohol
Butanol
C 4 H 9 OH
Nomenclature Of Alcohols
IUPAC Method
The last e of the parent alkane is replaced by ol to indicate
the presence of – OH Group.
Example
(i) CH 3 OH
Common Name: Methyl Alcohol
IUPAC Name: Methanol
As the parent contains one carbon atom so parent alkane is
called methane. As it also contains hydroxyl group the last e of
the alkane is replaced by ol forming methanol. In common
name methyl followed by the word alcohol.
Ethanol (Ethyl Alcohol)
Chemical Formula – CH 3 CH 2 OH Or C 2 H 5 OH
Ethanol is most common and most widely used alcohol. In
some cases ethanol is just called alcohol.
Physical Properties Of Ethanol
1. It is a colourless liquid having a pleasant smell and
burning taste.
2.
3.
4.
5.
6.
7.
Ethanol is a volatile liquid having a low boiling point of
780C.
It is lighter than water and mixes in it in any proportion.
Ethanol is a covalent compound not containing any ions.
Ethanol containing 5 % water is called rectified spirit.
Ethanol has no effect on any litmus solution.
Ethanol does not conduct electricity.
Chemical Properties Of Ethanol
1. Combustion
Ethanol is highly inflammable liquid. It catches fire very easily
and starts burning. Ethanol burns readily in air with a blue
flame to form carbon dioxide and water vapour.
Cumbustion
C 2 H 5 OH + 3O 2    → 2CO 2 + 3H 2 O + energy
A lot of heat is produced during this process.
Note
All alcohols like methanol, propanol etc. burn in air to form
CO 2 and water and produce a lot of heat.
2. Reaction With Sodium Metal
Ethanol reacts with sodium to form sodium ethoxide and
hydrogen gas
2C 2 H 5 OH + 2Na
→
2 C 2 H 5 ONa + H 2
Note: -This property shows the mild acidic nature of alcohol.
This reaction is used as a test for ethanol.
3. Oxidation
Oxidation means controlled combustion. Oxidation of ethanol
is of two types.
Strong Oxidation (Complete Oxidation)
When ethanol is heated with alkaline potassium permanganate
solution (an aqueous solution of potassium permanganate
containing sodium hydroxide) its complete oxidation takes
place and ethanoic acid is formed.
Alkaline
→ CH 3 COOH + H 2 O
CH 3 CH 2 OH + 2[O]   
This reaction can be carried out by adding 5 percent solution
of potassium permanganate in sodium hydroxide solution to
ethanol, drop wise till the purple colour of potassium
permanganate solution no longer disappears.
Actually the complete oxidation of alcohol occurs in two steps.
CH 3 CH 2 OH + [O]
Oxidation)
CH 3 CHO + [O]
→
CH 3 CHO
→ CH 3 COOH
+
H2O
(Mild
(Strong Oxidation)
Note
All the alcohols form carboxylic acids on complete oxidation
with strong oxidizing agents.
4. Reaction With Ethanoic Acid (Esterification)
Ethanol reacts with ethanoic acid in the presence of a few
drops of concentrated sulphuric acid to form sweet smelling
ester.
Conc. H2SO 4
CH 3 COOC 2 H 5 + H 2 O
CH 3 COOH + C 2 H 5 OH
Ethanoic
Acid
Note
Ethanol
Ester
Ethyl Acetate
All alcohols react with carboxylic acids to form sweet smelling
esters in the presence of little amount of concentrated
sulphuric acid.
Uses Of Esters
(i) Used in making perfumes.
(ii) Used as flavouring substances.
5. Dehydration Of Ethanol
This is a reaction to give unsaturated hydrocarbons. When
ethanol is heated at 443 K with excess of concentrated
sulphuric acid, it results in the dehydration of ethanol to give
ethane –
Hot conc.
C2H4 + H2O
C 2 H 5 OH

→
H2 SO 4
Ethanol
Ethene
Uses Of Ethanol
1. Used in the manufacture of paints, varnishes, lacquers,
medicines, perfumes, dyes, soaps and synthetic rubber.
2. It is used in the preparation of organic compounds like
ether, chloroform and iodoform.
3. It is used as liquid in alcohol thermometers and in spirit
lamps.
4. It is used as fuel in internal combustion engines and as a
substitute for petrol in motorcars as power alcohol.
5. It is used as an antiseptic to sterilize wounds and syringes
in hospitals.
6. It is used in alcoholic drinks like whisky, wine, beer and
other liquors.
7. Ethyl alcohol is used as a solvent.
8. Ethanol is used for making antifreeze mixtures, which are
used in the radiators of motor vehicles in cold countries.
Harmful Effects Of Alcohol
1. Alcohol is an intoxicant, so under the influence of alcohol
a person looses his sense of discrimination.
2. Alcohol drinking ruins the health of a person concerned. It
damages the liver and makes the brain dull.
3. The drinking of adulterated alcohol containing methyl
alcohol causes severe poisoning leading to blindness and
even death.
4. The alcohol drinking by the head of the family has a very
bad effect on the psychological development of children.
Denatured Alcohol
It is the ethanol which has been made unfit for drinking
purposes by adding poisonous substances like methanol,
pyridine, copper sulphate etc.
2. Aldehydes – CHO
O
||
Aldehydes are compounds containing carbonyl group, − C −
group, so it is also known as carbonyl compound. The carbon
atom of the carbonyl group has two free valencies (-C-) so two
atoms or groups of atoms can be attached to the carbon atom
of carbonyl group. In aldehydes, the carbon atom of carbonyl
group is attached to one alkyl group and one hydrogen atom
and is represented as follows: O
||
Or
Or
R − CHO
RCHO
R −C −H
Like alcohols aldehydes are also the organic compounds which
are made up of only carbon, hydrogen and oxygen elements.
Homologous Series Of Aldehydes
Aldehydes form the following homologous series.
General Formula
C n H 2n+1 CHO
Where n is the number of carbon atoms.
Nomenclature Of Aldehydes
IUPAC Name
The IUPAC name of an aldehyde is obtained from the parent
alkane by replacing the last letter e with a suffix al.
First five members of homologous series of aldehydes are:Common Name
IUPAC Name
Aldehyde Formula
Formaldehyde
Methanal
HCHO
Acetaldehyde
Ethanal
CH 3 CHO
Propionaldehyde
Propanal
C 2 H 5 CHO
Butyraldehyde
Butanal
C 3 H 7 CHO
3. Ketones – C O–
Ketones are the carbon compounds having carbonyl group so
it is called carbonyl compound. Ketones are the organic
O
||
compounds containing Ketonic group – C – or – C O – .
Ketonic group always occurs in the middle of a carbon chain
and the simplest ketone must contain at least three carbon
atoms in its molecule. There can be no ketone with less then 3
carbon atoms.
Where R is an alkyl group. The members are: Common Name
Formic Acid
Acetic Acid
Propionic Acid
Butrylic Acid
Valeric Acid
Common Naming
Alkyl groups are named first in increasing order and are
followed by the word 'Ketone'.
General Formula For Ketones
C n H 2n O
Where n is the number of carbon atoms. The first few
members of homologous series of ketones are: Common Name
IUPAC
Chemical
Name
Formula
Acetone,
Propanone
CH 3 COCH 3
Dimethyl Ketone
Methyl Ethyl
Butanone
CH 3 CO C 2 H 5
Ketone
Methyl Propyl
Pentanone
CH 3 CO C 3 H 7
Ketone
O
||
4. Carboxylic Acids (Alkanoic Acids) − C − OH
Physical Properties Of Ethanoic Acid
1. Colourless liquid having sour taste and a smell of vinegar.
2. The boiling point of ethanoic acid is 1180C.
3. When pure ethanoic acid is cooled, it freezes to form a
colourless, ice like liquid called glacial ethanoic acid.
4. Ethanoic acid is miscible with water in all proportions.
Chemical Properties Of Ethanoic Acid
1. Action On Litmus
Ethanoic acid is acidic in nature, being acidic in nature,
ethanoic acid turns blue litmus solution red.
2.
Reaction With Sodium Carbonate
Ethanoic acid reacts with sodium carbonate to form
sodium ethanoate and carbon dioxide gas.
2 CH 3 COOH + Na 2 CO 3 → 2 CH 3 COONa + CO 2 +
H2O
All carboxylic acids react in a similar way.
3.
Reaction With Sodium Hydrogen Carbonate
Ethanoic acid reacts with sodium hydrogen carbonate to
evolve brisk effervescence of carbon dioxide gas.
CH 3 COOH + NaHCO 3
H2O
Homologous Series Of Carboxylic Acids
Carboxylic acids form homologous series as follows: Nomenclature Of Carboxylic Acids
IUPAC System
The carboxylic acids are named as alkanoic acids. The IUPAC
name is obtained by replacing the last e of the parent alkane
by oic and adding the word acid to the name obtained.
General Formula R –COOH
→
CH 3 COONa + CO 2 +
All aldehydes react is a similar way.
4.
Reaction With Alkalis (Sodium Hydroxide)
Ethanoic acid reacts with alkalis to form salts and water.
Ethanoic acid reacts with sodium hydroxide to form
sodium ethanoate and water.
CH 3 COOH + NaOH → CH 3 COONa + H 2 O
All Carboxylic acids reacts in a similar way.
5.
Or –COOH
The carbon compounds containing carboxyl group (--COOH)
are called carboxylic acids. The carboxylic acids are made up
of three elements i.e., carbon, hydrogen and oxygen.
Formula
HCOOH
CH 3 COOH
C 2 H 5 COOH
C 3 H 7 COOH
C 4 H 7 COOH
Ethanoic Acid (Acetic Acid)
General Formula CH 3 COOH
A dilute solution of ethanoic acid in water is called vinegar.
Homologous Series Of Ketones
Ketones form the following homologues series.
Nomenclature Of Ketones
IUPAC Naming
The last e of the parent alkane is replaced by one.
IUPC Name
Methanoic Acid
Ethanoic Acid
Propanoic Acid
Butanoic Acid
Pentanoic Acid
H2O
Reaction With Alcohols (Esterification)
Ethanoic acid reacts with alcohols in the presence of a
little concentrated sulphuric acid to form esters.
CH 3 COOH
+
C 2 H 5 OH
Conc.H SO
4
2 
→
CH 3 COOC 2 H 5 +
All carboxylic acids react in a similar way.
6.
Saponification
That reaction in which carboxyl group is removed (i.e. a
molecule of CO 2 ) is called decarboxylation reaction.
When sodium ethanoate is heated with soda lime, the
methane gas is formed.
CH 3 COOC 2 H 5
CH 3 COONa
+
NaOH
Heat
 
→ C 2 H 5 OH
+
Chemical Properties Of Carbon Compounds
All carboxylic acids react in a similar way.
Uses Of Ethanoic Acid
1. Dilute ethanoic acid (vinegar) is used as a food
preservative in the preparation of pickles and sauces. It is
also used as an appetizer for dressing food dishes.
2. Ethanoic acid is used for making cellulose acetate, which
is an important artificial fibre.
3. It is used in the manufacture of acetone and esters in
perfumes.
4. It is used in the preparation of dyes, plastics and
pharmaceuticals.
5. It is used to coagulate rubber from latex.
6. It is used for making white lead used as a white paint.
7. It is used as a reagent in chemistry laboratory.
5. Halogens –X
The halogen group consists of elements of group 17 of
the periodic table.
Nomenclature Of Halogens
IUPAC System
The halogens are named by placing prefixes with the
name of the alkane to which it is attached. The prefix will
depend upon the particular halogen to which it is
attached.
1. Combustion
Carbon in all its allotropic forms burns in oxygen to give
carbon dioxide, heat and light. Most carbon compounds also
release a large amount of heat on burning.
C
+
CH 4 +
Light
O2
O2
→
CO 2
→
CO 2
+
Heat and Light
+
H2O
+ Heat and
Saturated hydrocarbons will generally give a clean flame while
unsaturated carbon compounds will give yellow flame with lots
of black smoke also called a sooty flame. However a limited
supply of air results in incomplete combustion of even
saturated hydrocarbons giving a sooty flame.
2. Oxidation
In the oxidation process only limited supply of oxygen is given
to carbon compounds so as to add oxygen to them. Some
substances are capable of adding oxygen to others, they are
called oxidizing agents. For example alkaline potassium
permanganate and acidified potassium dichromate are strong
oxidizing agents.
By the oxidation of alcohols they can be converted into
carboxylic acids.
Alkaline KMnO 4 + Heat
CH 3 COOH + H 2 O
CH 3 CH 2 OH + 2[O] →
Or acidifiedK 2 Cr2 O7 + Heat
Ethanol
Chloro-methane
Chloro-propane
Common Name
Methyl chloride
Ethyl chloride
Propyl chloride
Butyl chloride
Pentyl chloride
Bromo- propane
IUPC Name
Chloro methane
Chloro ethane
Chloro propane
Chloro butane
Chloro pentane
Formula
CH 3 Cl
C 2 H 5 Cl
C 3 H 7 Cl
C 4 H 9 Cl
C 5 H 11 Cl
Ethanoic Acid
3. Addition Reactions
Unsaturated hydrocarbons add hydrogen in the presence of
catalysts such as palladium or nickel to give saturated
hydrocarbons. This reaction is generally used in the
hydrogenation of vegetable oils using a nickel catalyst.
Catalyst
A catalyst is a substance that causes a reaction to occur or
proceed at a different rate without the catalyst itself being
affected.
Hydrogenation Of Alkynes
6. Esters –COO–
Esters are chemical compounds consisting of a carbonyl
group adjacent to an ether linkage.
Ethyl ethanoate
Nomenclature Of Esters
An ester name has two parts - the part that comes from
the acid and the part that comes from alcohol. First the
name of the alkyl derived from alcohol is written. This is
followed by the name of the parent chain form the
carboxylic acid part of the ester with an –e remove and
replaced with the ending –oate.
Common Name
Methyl acetate
Ethyl acetate
Propyl acetate
Butyl acetate
Pentyl acetate
IUPC Name
Methyl ethnoate
Ethyl ethanoate
Propyl ethanoate
Butyl ethanoate
Pentyl ethanoate
Formula
CH 3 COOCH 3
CH 3 COOC 2 H 5
CH 3 COOC 3 H 7
CH 3 COOC 4 H 9
CH 3 COOC 5 H 11
Halogenation of Alkynes
4. Substitution Reactions
Those reactions in which one type of atom or a group of
atoms takes the place of another are called substitution
reactions.
Saturated hydrocarbons are unreactive and are inert in the
presence of most reagents. However in the presence of
sunlight chlorine can be added to hydrocarbons in a very fast
reaction. Chlorine can replace hydrogen atoms one by one.
Therefore it is called a substitution reaction.
Sunlight
+ Cl 2 
+ HCl
CH 4
→ CH 3 Cl
Chloro Methane
CH 3 Cl
+
Cl 2
→
CH 2 Cl 2 +
Cl 2
CHCl 3 + HCl
→
Trichloro Methane (Chloroform)
CHCl 3
Cl 2
CCl 4
+ HCl
→
TetrachloroMethane( Carbon tetrachloride)
+
CH 2 Cl 2 + HCl
Dichloro Methane
Soaps And Synthetic Detergents
Detergent
Any substance which has cleansing action in water is called
detergent. There are two types of detergents: 1. Soapy detergents (Soaps)
2. Non-Soapy detergents (Synthetic Detergents)
(iv) During cleansing, the hydrocarbon part attaches itself to
dirt.
(v) On agitation in washing machine or rubbing with hands,
the oil and grease surrounded by soap are removed from
dirty surface and break in to fragments.
(vi) The ionic part of the soap molecule, remains attached to
water.
(vii) When clothes are rinsed in water the dirt particles
attached to soap molecule get washed away in water and
the cloth gets cleaned.
Limitations Of Soaps
Soaps
A soap is a sodium salt of a long chain carboxylic acid which
has cleaning properties in water.
Examples
Sodium stearate, sodium oleate, sodium palmitate.
1. Soap Does Not Work Effectively In Hard Water
Hard water contains calcium ions and magnesium ions. These
ions present in hard water reac5 with the carboxylate ions of
the soap forming on insoluble precipitate called scum.
Types Of Soaps
1. Hard Soaps
Sodium salts of fatty acids are known as hard soap. They
are prepared from cheap oils and fats and sodium
hydroxide. They have free alkali and are used for washing
clothes.
The scum sticks to the clothes, utensils and skin. Thus soap
looses its properties of cleansing in hard water.
2.
Soft Soaps
They are prepared from good oils and potassium
hydroxide. They are free from alkali, form more lather and
are used in toilet soaps, shaving creams, shampoos.
Structure Of Soap Molecule
A soap molecule consists of two parts
(i) A long hydrocarbon chain (hydrophobic)
(ii) A short ionic part (hydrophilic)
C17 H35 COONa + Ca2 +
→ ( C17 H35 COO
2. Soap Does Not Work In Acidic Solutions
Acidic water contains H+ ions. When soap is dissolved in
acidic water, its carboxylate ions ( RCOO − ) react with H +
ions forming back the free fatty acids.
C 17 H 35 COO − + H + → C 17 H 35 COOH
The soap thus looses its property of cleansing.
Synthetic Detergent (Soap Less Soap)
Chemically detergents are sodium salts of long chain benzene
sulphonic acid or a long chain alkyl hydrogen sulphate which
has cleansing property in water.
Example
Sodium n-Dodecyl Benzene Sulphonate
CH 3 – (CH 2 ) 11 – C 6 H 4 – SO 3
Cleansing Action Of Soaps And Detergents
The cleansing action of soaps and detergents follows the same
principle.
Soaps and detergents consists of a large hydrophobic
(water repelling) hydrocarbon tail with a negative
hydrophilic (water attracting) head.
(ii) In solution polar water molecules surround the ions and
not the organic part of the molecule.
(iii) On dissolving soap or detergent in water the molecules
gather together as clusters called micelles with tails
sticking inwards and heads outwards.
) 2 Ca + 2Na +
−
Na +
Structure Of A Detergent Molecule
A synthetic detergent molecule consists of two parts
(i) A long hydrocarbon chain (hydrophobic)
(ii) A short ionic part (hydrophilic)
(i)
Disadvantages Of Synthetic Detergents Over Soaps
(i) Some of the synthetic detergents are non-biodegradable
hence cause pollution.
(ii) Some detergents may cause harm to the skin due to
prolonged use.
Advantages Of Detergents Over Soaps
(i) Synthetic detergents are effective in hard water.
(ii) Synthetic detergents are effective in acidic water.
(iii) Vegetable oils which are used for the preparation of soaps
can be used for human consumptions.
Differences Between Soaps And Detergents
Soaps
Detergents
1. Soap is a sodium or Detergents are sodium or
potassium salt of higher potassium salts of long chain
fatty acid.
alkyl hydrogen sulphates.
2. Soaps are prepared from Synthetic detergents are
natural fats and oils.
prepared from hydrocarbon
obtained from petroleum.
3. They are biodegradable.
They are non biodegradable.
4. Soaps are not suitable for Detergents can be easily
washing in hard water.
used even in hard water.
5. They cannot be used in They can be used easily in
acidic medium as they are the acidic medium as they
decomposed in the acidic are not decomposed in the
medium.
acidic medium.