CARBON AND ITS COMPOUNDS.pdf

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CARBON AND ITS COMPOUNDS




CARBON


Free state

Combined state


Crystalline

Amorphous

Diamond

Graphite

Buckminster

fullerenes

Coke



Charcoal


In living organisms

In non
-
living system

Carbohydrates

Fats

Proteins


Carbonates

CO
2

Coal

Petroleum

Natural gas



Difference between Diamond and Graphite

1.

Diamond has a three
-
dimensional network
structure.

1.

Graphite has a two
-
dimensional sheet like
structure consisting of a number of benzene
rings fused together.


2.

It is the hardest natur
al substance known.

2.

Graphite is soft and greasy and is used as
solid lubricant for heavy machinery
operating at high temperatures.

3.

It is a bad conductor of electricity but is a
very good conductor of heat. Because of
hardness and high thermal conduc
tivity,
diamond tipped tools do not overheat and
hence are extensively used for cutting and
drilling purposes.

3.

It is a good conductor of both heat and
electricity. Because of high electrical
conductivity, graphite is used for making
electrodes of batter
y and arcs.

4.

It is a transparent substance with high
refractive index. Therefore, it is used for
making gemstones and jewellery.

4.

It is an opaque grayish black substance.




Simplest compounds of carbon are HYDROCARBONS

(compounds having atoms
of car
bon and hydrogen only)

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HYDROCARBONS


Saturated

Unsaturated


ALKENE

ALKYNE


(Suffix
→
ENE)

(Suffix
→
YNE)


General formula

General formula


C
n
H
2n

C
n
H
2n
–
2

ALKANE

(Suffix
→
ANE)

General formula

C
n
H
2n

+ 2

Single bond between
carbon atoms

Double bond

between C
-
atoms

Triple bond

between C
-
ato
ms




Organic compounds:

Hydrocarbons and their derivatives are organic compounds.
(Organic chemical substances of animal or plant origin
)
.



Hydrocarbons:

Comp
ounds made of carbon and hydrog
en are known as
hy
drocarbons.

Formula of
functional group

Name of

functional group

Formula of compound

containing group

Name of

compound

–

OH

Alcohol

C
2
H
5
OH

Ethanol

–

CHO

Aldehyde

HCHO

Methanal

–

COOH

Carboxylic acid

CH
3
COOH

Ethanoic acid

> C = 0

Ketone

H
3
C CO CH
3

Pro
panone

–

X (a halogen)

Halogen

CH
3

–

Cl

Chloromethane

–

NH
2

Amino

CH
3

NH
2

Methanamine

–

NH
2

Nitro

CH
3

NO
2

Nitromethane



Catenation:

It is a unique property found in some elements as in carbon in which
carbon atoms have the ability of combining with th
emselves to form numerous compounds in
different ways.


Organic chemistry:

Study of hydrocarbons and their derivatives is called organic
chemistry.


Aromatic compounds:

Organic compounds in which carbon atoms are arranged in a
six member
ed

ring having char
acteristic properties (Aroma/smell) (Ring or closed chain
compounds).


Aliphatic compounds:

Compounds in which carbon atoms are arranged one after
another in a chain like fashion (Open or straight chain compounds).


Saturated compounds:

Compounds in which
all the bonds between the atoms are
single bonds.


Unsaturated compounds:

Compounds, which contain a carbon
-
carbon double bond
or a carbon
-
carbon triple bond.


Functional Group:

A characteristic group present in a
n organic compound. (Eg.
aldehyde, alcohol,

acid

etc.)


Isomerism:

The phenomenon in which different compounds have different structural
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formulae but same molecular formula.


Molecular formula:

Gives the exact number of atoms of various elements present in
a compound.


Combustion:

Burning an organi
c compound in air or oxygen. Carbon dioxide and
water are the products of combustion of any carbon compound.


Molasses:

The mother liquor left after the crystallization of cane sugar.


Rectified sprit:

95.6% pure alcohol.


Esterification:

Formation of an

ester by the combination of an acid with an alcohol.



IUPAC SYSTEM OF NOMENCLATURE

1.

The longest chain of carbon atoms in the structure of the compound (to be named) is
found first. The compound is then named as a derivative of the alkane hydrocarbon
wh
ich corresponds to the longest chain of carbon atoms (This

is called parent
hydrocarbon).

2.

The alkyl groups present as side chains (branches) are considered as substituents and
named separately as methyl (CH
3
—
) or ethyl (C
2
H
5
—
) groups.

3.

The carbon atom
s of the longest carbon chain are numbered in such a way that the
alkyl groups (substituents) get the lowest possible number (smallest possible number).

4.

The position of alkyl group is indicated by writing the number of carbon atom to which
it is attache
d.

5.

Thus, IUPAC name is given as



Position and name of alkyl group + parent hydrocarbon

6.

If two same alkyl derivatives are present on same carbon atom, then prefix ‘di’ or ‘tri’
can be used.


Lets understand with the help of few examples:


Example 1:






C
H
3
—
C
H
—
C
H
3

CH
3

1

2

3



The longest chain contains three C
-
atoms. The saturated hydrocarbon containing three
carbon atoms is
propane.


The methyl group
–)
CH
(
3

is attached to C
-
atom number 2 (numbering from either side
gives numbe
r 2 to the C
-
atom to which the methyl group is attached).


Thus, the name of the compound is 2
-
methylpropane.


Example 2:


CH
3
—
CH
2
—
CH
2
—
CH
—
CH
3

CH
3

5

4

3

2

1



The longest chain contains five C
-
atoms. The saturated hydrocarbon containing five
C
-
atoms is pentane.


T
he numbering of C
-
atoms in the longest chain is done from the C
-
atom that is nearest
to the methyl group which is present as the branched chain. Thus,

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CH
3
—
CH
2
—
CH
2
—
CH
—
CH
3

CH
3

5

4

3

2

1

(correct)



This way of numbering is correct, but the way of numbering as shown below is

wrong.


CH
3
—
CH
2
—
CH
2
—
CH
—
CH
3

CH
3

1

2

3

4

5

(
wrong
)



Hence, the correct name will be 2
-
methylpentane (and not 4
-
methylpentane).


The functional groups are summarized in the table below :

S. No.

Hetero atom

Functional
Group

Formula of a
Functional
Group

Class of Compounds

1.

O

Hydroxyl

—
OH

Alcohols,


R
—
OH

2.

O

Aldehydic

—
CHO or


—
C
—
H


O



Aldehydes,

R
—
CHO

3.

O

Keto

—
CO
—

or


—
C
—


O



Ketones,


R
—
CO
—
R

4.

O

Carboxyl

—
COOH or


—
C
—
O
H


O



Carboxylic acids, R
—
COOH

5.

Cl,

Br

Halo (chloro,
bromo)

—
Cl,
—
Br

Haloalkanes, R
—
Cl, R
—
Br



Properties of carbon compounds:


(i)

Combustion:

to produce CO
2
, H
2
O and energy.



Energy
O
H
CO
OH
CH
2
2
O
3
2
+
+
⎯
⎯
→
⎯


(ii)

Oxidation:

to form other organic compounds.



Alcohol
Acid
Oxidation
⎯
⎯
⎯
→
⎯



HCOOH
OH
CH
4
KMnO

Alk.
3
⎯
⎯
⎯
⎯
⎯
→
⎯


(iii)

Addition reaction:

Characteristic property of
unsaturated hydrocarbons.

Reddish brown colour of bromine water gets decolourised.


2
|
|
Br
H
H
C
H
C
H
+
−
=
−
H
C
C
H
−
−
−
⎯
→
⎯
H
Br
|
|
H
Br
|
|


(iv)

Substitution reaction:
Characteristic proper
ty of

saturated compounds
→

displacement reaction.

)
ide
tetrachlor
carbon
(
omethane
tetrachlor
4
)
chloroform
(
2
ethane
trichlorom
3
2
2
2
2
ane
chlorometh
3
2
methane
4
CCl
Cl
CHCl
Cl
Cl
CH
Cl
Cl
CH
Cl
CH
→
+
→
+
→
+
→
+

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Properties of Ethanol

(CH
3
CH
2
OH)

combustion

CO
2
+ H
2
O + Energy

CH
3
COOH (Ethanoic acid)

oxidation

oxid. alk. KMnO
4

or acid K
2
Cr
2
O
7

CH
3
CH
2
ONa (Sodium ethoxide)

Na

CH
3
COOCH
2
CH
3
(Ethyl ethanoate)

CH
3
COOH

Esterification

CH
2
= CH
2
(Ethene)

conc. H
2
SO
4

Deh
ydration



Properties of Ethanoic Acid

(CH
3
COOH)

combustion

CO
2
+ H
2
O + Energy

CH
3
COONa + H
2
(Sodium ethanoate)

CH
3
COONa + H
2
O

NaOH

CH
3
COONa + CO
2
+ H
2
O

Na
2
CO
3

CH
3
COOCH
3
(Methyl Ethanoate)

CH
3
OH

Esterification

Na

Reduction

CH
3
CH
2
OH (Et
hanol)







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