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 Page 1


The replacement of hydrogen atom(s) in a
hydrocarbon, aliphatic or aromatic, by halogen
atom(s) results in the formation of alkyl halide
(haloalkane) and aryl halide (haloarene), respectively.
Haloalkanes contain halogen atom(s) attached to the
sp
3
 hybridised carbon atom of an alkyl group whereas
haloarenes contain halogen atom(s) attached to sp
2
hybridised carbon atom(s) of an aryl group. Many
halogen containing organic compounds occur in
nature and some of these are clinically useful. These
classes of compounds find wide applications in
industry as well as in day-to-day life. They are used
as solvents for relatively non-polar compounds and
as starting materials for the synthesis of wide range
of organic compounds. Chlorine containing antibiotic,
chloramphenicol, produced by soil microorganisms
is very effective for the treatment of typhoid fever.
Our body produces iodine containing hormone,
thyroxine, the deficiency of which causes a disease
called goiter. Synthetic halogen compounds, viz.
chloroquine is used for the treatment of malaria;
halothane is used as an anaesthetic during surgery.
Certain fully fluorinated compounds are being
considered as potential blood substitutes in surgery.
In this Unit, you will study the important methods
of preparation, physical and chemical properties and
uses of organohalogen compounds.
After studying this Unit, you will be
able to
• name haloalkanes and haloarenes
according to the IUPAC system of
nomenclature from their given
structures;
• describe the reactions involved in
the preparation of haloalkanes and
haloarenes and understand
various reactions that they
undergo;
• correlate the structures of
haloalkanes and haloarenes with
various types of reactions;
• use stereochemistry as a tool for
understanding the reaction
mechanism;
• appreciate the applications of
organo-metallic compounds;
• highlight the environmental effects
of polyhalogen compounds.
Objectives
10
Unit Unit Unit Unit Unit
10
Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and
Haloar Haloar Haloar Haloar Haloarenes enes enes enes enes
Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and
Haloar Haloar Haloar Haloar Haloarenes enes enes enes enes
Halogenated compounds persist in the environment due to their
resistance to breakdown by soil bacteria.
2015-16
Page 2


The replacement of hydrogen atom(s) in a
hydrocarbon, aliphatic or aromatic, by halogen
atom(s) results in the formation of alkyl halide
(haloalkane) and aryl halide (haloarene), respectively.
Haloalkanes contain halogen atom(s) attached to the
sp
3
 hybridised carbon atom of an alkyl group whereas
haloarenes contain halogen atom(s) attached to sp
2
hybridised carbon atom(s) of an aryl group. Many
halogen containing organic compounds occur in
nature and some of these are clinically useful. These
classes of compounds find wide applications in
industry as well as in day-to-day life. They are used
as solvents for relatively non-polar compounds and
as starting materials for the synthesis of wide range
of organic compounds. Chlorine containing antibiotic,
chloramphenicol, produced by soil microorganisms
is very effective for the treatment of typhoid fever.
Our body produces iodine containing hormone,
thyroxine, the deficiency of which causes a disease
called goiter. Synthetic halogen compounds, viz.
chloroquine is used for the treatment of malaria;
halothane is used as an anaesthetic during surgery.
Certain fully fluorinated compounds are being
considered as potential blood substitutes in surgery.
In this Unit, you will study the important methods
of preparation, physical and chemical properties and
uses of organohalogen compounds.
After studying this Unit, you will be
able to
• name haloalkanes and haloarenes
according to the IUPAC system of
nomenclature from their given
structures;
• describe the reactions involved in
the preparation of haloalkanes and
haloarenes and understand
various reactions that they
undergo;
• correlate the structures of
haloalkanes and haloarenes with
various types of reactions;
• use stereochemistry as a tool for
understanding the reaction
mechanism;
• appreciate the applications of
organo-metallic compounds;
• highlight the environmental effects
of polyhalogen compounds.
Objectives
10
Unit Unit Unit Unit Unit
10
Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and
Haloar Haloar Haloar Haloar Haloarenes enes enes enes enes
Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and
Haloar Haloar Haloar Haloar Haloarenes enes enes enes enes
Halogenated compounds persist in the environment due to their
resistance to breakdown by soil bacteria.
2015-16
282 Chemistry
Haloalkanes and haloarenes may be classified as follows:
These may be classified as mono, di, or polyhalogen (tri-,tetra-, etc.)
compounds depending on whether they contain one, two or more halogen
atoms in their structures. For example,
Monohalocompounds may further be classified according to the
hybridisation of the carbon atom to which the halogen is bonded, as
discussed below.
This class includes
(a) Alkyl halides or haloalkanes (R—X)
In alkyl halides, the halogen atom is bonded to an alkyl group (R).
They form a homologous series represented by C
n
H
2n+1
X. They are
further classified as primary, secondary or tertiary according to the
nature of carbon to which halogen is attached.
(b) Allylic halides
These are the compounds in which the halogen atom is bonded to an
sp
3
-hybridised carbon atom next to carbon-carbon double bond (C=C)
i.e. to an allylic carbon.
(c) Benzylic halides
These are the compounds in which the halogen atom is bonded to an
sp
3
-hybridised carbon atom next to an aromatic ring.
10.1 10.1 10.1 10.1 10.1 Classification Classification Classification Classification Classification
10.1.1On the
Basis of
Number of
Halogen
Atoms
10.1.2 Compounds
Containing
sp
3 
C—X
Bond (X= F,
Cl, Br, I)
2015-16
Page 3


The replacement of hydrogen atom(s) in a
hydrocarbon, aliphatic or aromatic, by halogen
atom(s) results in the formation of alkyl halide
(haloalkane) and aryl halide (haloarene), respectively.
Haloalkanes contain halogen atom(s) attached to the
sp
3
 hybridised carbon atom of an alkyl group whereas
haloarenes contain halogen atom(s) attached to sp
2
hybridised carbon atom(s) of an aryl group. Many
halogen containing organic compounds occur in
nature and some of these are clinically useful. These
classes of compounds find wide applications in
industry as well as in day-to-day life. They are used
as solvents for relatively non-polar compounds and
as starting materials for the synthesis of wide range
of organic compounds. Chlorine containing antibiotic,
chloramphenicol, produced by soil microorganisms
is very effective for the treatment of typhoid fever.
Our body produces iodine containing hormone,
thyroxine, the deficiency of which causes a disease
called goiter. Synthetic halogen compounds, viz.
chloroquine is used for the treatment of malaria;
halothane is used as an anaesthetic during surgery.
Certain fully fluorinated compounds are being
considered as potential blood substitutes in surgery.
In this Unit, you will study the important methods
of preparation, physical and chemical properties and
uses of organohalogen compounds.
After studying this Unit, you will be
able to
• name haloalkanes and haloarenes
according to the IUPAC system of
nomenclature from their given
structures;
• describe the reactions involved in
the preparation of haloalkanes and
haloarenes and understand
various reactions that they
undergo;
• correlate the structures of
haloalkanes and haloarenes with
various types of reactions;
• use stereochemistry as a tool for
understanding the reaction
mechanism;
• appreciate the applications of
organo-metallic compounds;
• highlight the environmental effects
of polyhalogen compounds.
Objectives
10
Unit Unit Unit Unit Unit
10
Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and
Haloar Haloar Haloar Haloar Haloarenes enes enes enes enes
Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and
Haloar Haloar Haloar Haloar Haloarenes enes enes enes enes
Halogenated compounds persist in the environment due to their
resistance to breakdown by soil bacteria.
2015-16
282 Chemistry
Haloalkanes and haloarenes may be classified as follows:
These may be classified as mono, di, or polyhalogen (tri-,tetra-, etc.)
compounds depending on whether they contain one, two or more halogen
atoms in their structures. For example,
Monohalocompounds may further be classified according to the
hybridisation of the carbon atom to which the halogen is bonded, as
discussed below.
This class includes
(a) Alkyl halides or haloalkanes (R—X)
In alkyl halides, the halogen atom is bonded to an alkyl group (R).
They form a homologous series represented by C
n
H
2n+1
X. They are
further classified as primary, secondary or tertiary according to the
nature of carbon to which halogen is attached.
(b) Allylic halides
These are the compounds in which the halogen atom is bonded to an
sp
3
-hybridised carbon atom next to carbon-carbon double bond (C=C)
i.e. to an allylic carbon.
(c) Benzylic halides
These are the compounds in which the halogen atom is bonded to an
sp
3
-hybridised carbon atom next to an aromatic ring.
10.1 10.1 10.1 10.1 10.1 Classification Classification Classification Classification Classification
10.1.1On the
Basis of
Number of
Halogen
Atoms
10.1.2 Compounds
Containing
sp
3 
C—X
Bond (X= F,
Cl, Br, I)
2015-16
283 Haloalkanes and Haloarenes
This class includes:
(a) Vinylic halides
These are the compounds in which the halogen atom is bonded to
an sp
2
-hybridised carbon atom of a carbon-carbon double bond
(C = C).
(b) Aryl halides
These are the compounds in which the halogen atom is bonded to
the sp
2
-hybridised carbon atom of an aromatic ring.
Having learnt the classification of halogenated compounds, let us now
learn how these are named. The common names of alkyl halides are
derived by naming the alkyl group followed by the halide. Alkyl halides
are named as halosubstituted hydrocarbons in the IUPAC system of
nomenclature. Haloarenes are the common as well as IUPAC names of
aryl halides. For dihalogen derivatives, the prefixes o-, m-, p- are used in
common system but in IUPAC system, the numerals 1,2; 1,3 and 1,4 are
used.
10.2 Nomenclature 10.2 Nomenclature 10.2 Nomenclature 10.2 Nomenclature 10.2 Nomenclature
10.1.3 Compounds
Containing
sp
2 
C—X
Bond
The dihaloalkanes having the same type of halogen atoms are named
as alkylidene or alkylene dihalides. The dihalo-compounds having same
type of halogen atoms are further classified as geminal halides (halogen
atoms are present on the same carbon atom) and vicinal halides (halogen
atoms are present on the adjacent carbon atoms). In common name
system, gem-dihalides are named as alkylidene halides and vic-dihalides
2015-16
Page 4


The replacement of hydrogen atom(s) in a
hydrocarbon, aliphatic or aromatic, by halogen
atom(s) results in the formation of alkyl halide
(haloalkane) and aryl halide (haloarene), respectively.
Haloalkanes contain halogen atom(s) attached to the
sp
3
 hybridised carbon atom of an alkyl group whereas
haloarenes contain halogen atom(s) attached to sp
2
hybridised carbon atom(s) of an aryl group. Many
halogen containing organic compounds occur in
nature and some of these are clinically useful. These
classes of compounds find wide applications in
industry as well as in day-to-day life. They are used
as solvents for relatively non-polar compounds and
as starting materials for the synthesis of wide range
of organic compounds. Chlorine containing antibiotic,
chloramphenicol, produced by soil microorganisms
is very effective for the treatment of typhoid fever.
Our body produces iodine containing hormone,
thyroxine, the deficiency of which causes a disease
called goiter. Synthetic halogen compounds, viz.
chloroquine is used for the treatment of malaria;
halothane is used as an anaesthetic during surgery.
Certain fully fluorinated compounds are being
considered as potential blood substitutes in surgery.
In this Unit, you will study the important methods
of preparation, physical and chemical properties and
uses of organohalogen compounds.
After studying this Unit, you will be
able to
• name haloalkanes and haloarenes
according to the IUPAC system of
nomenclature from their given
structures;
• describe the reactions involved in
the preparation of haloalkanes and
haloarenes and understand
various reactions that they
undergo;
• correlate the structures of
haloalkanes and haloarenes with
various types of reactions;
• use stereochemistry as a tool for
understanding the reaction
mechanism;
• appreciate the applications of
organo-metallic compounds;
• highlight the environmental effects
of polyhalogen compounds.
Objectives
10
Unit Unit Unit Unit Unit
10
Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and
Haloar Haloar Haloar Haloar Haloarenes enes enes enes enes
Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and
Haloar Haloar Haloar Haloar Haloarenes enes enes enes enes
Halogenated compounds persist in the environment due to their
resistance to breakdown by soil bacteria.
2015-16
282 Chemistry
Haloalkanes and haloarenes may be classified as follows:
These may be classified as mono, di, or polyhalogen (tri-,tetra-, etc.)
compounds depending on whether they contain one, two or more halogen
atoms in their structures. For example,
Monohalocompounds may further be classified according to the
hybridisation of the carbon atom to which the halogen is bonded, as
discussed below.
This class includes
(a) Alkyl halides or haloalkanes (R—X)
In alkyl halides, the halogen atom is bonded to an alkyl group (R).
They form a homologous series represented by C
n
H
2n+1
X. They are
further classified as primary, secondary or tertiary according to the
nature of carbon to which halogen is attached.
(b) Allylic halides
These are the compounds in which the halogen atom is bonded to an
sp
3
-hybridised carbon atom next to carbon-carbon double bond (C=C)
i.e. to an allylic carbon.
(c) Benzylic halides
These are the compounds in which the halogen atom is bonded to an
sp
3
-hybridised carbon atom next to an aromatic ring.
10.1 10.1 10.1 10.1 10.1 Classification Classification Classification Classification Classification
10.1.1On the
Basis of
Number of
Halogen
Atoms
10.1.2 Compounds
Containing
sp
3 
C—X
Bond (X= F,
Cl, Br, I)
2015-16
283 Haloalkanes and Haloarenes
This class includes:
(a) Vinylic halides
These are the compounds in which the halogen atom is bonded to
an sp
2
-hybridised carbon atom of a carbon-carbon double bond
(C = C).
(b) Aryl halides
These are the compounds in which the halogen atom is bonded to
the sp
2
-hybridised carbon atom of an aromatic ring.
Having learnt the classification of halogenated compounds, let us now
learn how these are named. The common names of alkyl halides are
derived by naming the alkyl group followed by the halide. Alkyl halides
are named as halosubstituted hydrocarbons in the IUPAC system of
nomenclature. Haloarenes are the common as well as IUPAC names of
aryl halides. For dihalogen derivatives, the prefixes o-, m-, p- are used in
common system but in IUPAC system, the numerals 1,2; 1,3 and 1,4 are
used.
10.2 Nomenclature 10.2 Nomenclature 10.2 Nomenclature 10.2 Nomenclature 10.2 Nomenclature
10.1.3 Compounds
Containing
sp
2 
C—X
Bond
The dihaloalkanes having the same type of halogen atoms are named
as alkylidene or alkylene dihalides. The dihalo-compounds having same
type of halogen atoms are further classified as geminal halides (halogen
atoms are present on the same carbon atom) and vicinal halides (halogen
atoms are present on the adjacent carbon atoms). In common name
system, gem-dihalides are named as alkylidene halides and vic-dihalides
2015-16
284 Chemistry
are named as alkylene dihalides. In IUPAC system, they are named as
dihaloalkanes.
Structure Common name IUPAC name
CH 3CH 2CH(Cl)CH 3 sec-Butyl chloride 2-Chlorobutane
(CH
3
)
3
CCH
2
Br neo-Pentyl bromide 1-Bromo-2,2-dimethylpropane
(CH3)3CBr tert-Butyl bromide 2-Bromo-2-methylpropane
CH
2 
= CHCl Vinyl chloride Chloroethene
CH
2 
= CHCH
2
Br Allyl bromide 3-Bromopropene
CH 2Cl 2 Methylene chloride Dichloromethane
CHCl
3
Chloroform Trichloromethane
CHBr
3
Bromoform Tribromomethane
CCl4 Carbon tetrachloride Tetrachloromethane
CH
3
CH
2
CH
2
F n-Propyl fluoride 1-Fluoropropane
o-Chlorotoluene 1-Chloro-2-methylbenzene
or
2-Chlorotoluene
Benzyl chloride Chlorophenylmethane
Table 10.1: Common and IUPAC Names of some Halides
Example 10.1 Example 10.1 Example 10.1 Example 10.1 Example 10.1
Solution Solution Solution Solution Solution
Draw the structures of all the eight structural isomers that have the
molecular formula C
5
H
11
Br. Name each isomer according to IUPAC system
and classify them as primary, secondary or tertiary bromide.
CH
3
CH
2
CH
2
CH
2
CH
2
Br 1-Bromopentane (1
o
)
CH
3
CH
2
CH
2
CH(Br)CH
3
2-Bromopentane(2
o
)
CH
3
CH
2
CH(Br)CH
2
CH
3
3-Bromopentane (2
o
)
(CH
3
)
2
CHCH
2
CH
2
Br 1-Bromo-3-methylbutane (1
o
)
Some common examples of halocompounds are mentioned in Table 10.1.
2015-16
Page 5


The replacement of hydrogen atom(s) in a
hydrocarbon, aliphatic or aromatic, by halogen
atom(s) results in the formation of alkyl halide
(haloalkane) and aryl halide (haloarene), respectively.
Haloalkanes contain halogen atom(s) attached to the
sp
3
 hybridised carbon atom of an alkyl group whereas
haloarenes contain halogen atom(s) attached to sp
2
hybridised carbon atom(s) of an aryl group. Many
halogen containing organic compounds occur in
nature and some of these are clinically useful. These
classes of compounds find wide applications in
industry as well as in day-to-day life. They are used
as solvents for relatively non-polar compounds and
as starting materials for the synthesis of wide range
of organic compounds. Chlorine containing antibiotic,
chloramphenicol, produced by soil microorganisms
is very effective for the treatment of typhoid fever.
Our body produces iodine containing hormone,
thyroxine, the deficiency of which causes a disease
called goiter. Synthetic halogen compounds, viz.
chloroquine is used for the treatment of malaria;
halothane is used as an anaesthetic during surgery.
Certain fully fluorinated compounds are being
considered as potential blood substitutes in surgery.
In this Unit, you will study the important methods
of preparation, physical and chemical properties and
uses of organohalogen compounds.
After studying this Unit, you will be
able to
• name haloalkanes and haloarenes
according to the IUPAC system of
nomenclature from their given
structures;
• describe the reactions involved in
the preparation of haloalkanes and
haloarenes and understand
various reactions that they
undergo;
• correlate the structures of
haloalkanes and haloarenes with
various types of reactions;
• use stereochemistry as a tool for
understanding the reaction
mechanism;
• appreciate the applications of
organo-metallic compounds;
• highlight the environmental effects
of polyhalogen compounds.
Objectives
10
Unit Unit Unit Unit Unit
10
Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and
Haloar Haloar Haloar Haloar Haloarenes enes enes enes enes
Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and Haloalkanes and
Haloar Haloar Haloar Haloar Haloarenes enes enes enes enes
Halogenated compounds persist in the environment due to their
resistance to breakdown by soil bacteria.
2015-16
282 Chemistry
Haloalkanes and haloarenes may be classified as follows:
These may be classified as mono, di, or polyhalogen (tri-,tetra-, etc.)
compounds depending on whether they contain one, two or more halogen
atoms in their structures. For example,
Monohalocompounds may further be classified according to the
hybridisation of the carbon atom to which the halogen is bonded, as
discussed below.
This class includes
(a) Alkyl halides or haloalkanes (R—X)
In alkyl halides, the halogen atom is bonded to an alkyl group (R).
They form a homologous series represented by C
n
H
2n+1
X. They are
further classified as primary, secondary or tertiary according to the
nature of carbon to which halogen is attached.
(b) Allylic halides
These are the compounds in which the halogen atom is bonded to an
sp
3
-hybridised carbon atom next to carbon-carbon double bond (C=C)
i.e. to an allylic carbon.
(c) Benzylic halides
These are the compounds in which the halogen atom is bonded to an
sp
3
-hybridised carbon atom next to an aromatic ring.
10.1 10.1 10.1 10.1 10.1 Classification Classification Classification Classification Classification
10.1.1On the
Basis of
Number of
Halogen
Atoms
10.1.2 Compounds
Containing
sp
3 
C—X
Bond (X= F,
Cl, Br, I)
2015-16
283 Haloalkanes and Haloarenes
This class includes:
(a) Vinylic halides
These are the compounds in which the halogen atom is bonded to
an sp
2
-hybridised carbon atom of a carbon-carbon double bond
(C = C).
(b) Aryl halides
These are the compounds in which the halogen atom is bonded to
the sp
2
-hybridised carbon atom of an aromatic ring.
Having learnt the classification of halogenated compounds, let us now
learn how these are named. The common names of alkyl halides are
derived by naming the alkyl group followed by the halide. Alkyl halides
are named as halosubstituted hydrocarbons in the IUPAC system of
nomenclature. Haloarenes are the common as well as IUPAC names of
aryl halides. For dihalogen derivatives, the prefixes o-, m-, p- are used in
common system but in IUPAC system, the numerals 1,2; 1,3 and 1,4 are
used.
10.2 Nomenclature 10.2 Nomenclature 10.2 Nomenclature 10.2 Nomenclature 10.2 Nomenclature
10.1.3 Compounds
Containing
sp
2 
C—X
Bond
The dihaloalkanes having the same type of halogen atoms are named
as alkylidene or alkylene dihalides. The dihalo-compounds having same
type of halogen atoms are further classified as geminal halides (halogen
atoms are present on the same carbon atom) and vicinal halides (halogen
atoms are present on the adjacent carbon atoms). In common name
system, gem-dihalides are named as alkylidene halides and vic-dihalides
2015-16
284 Chemistry
are named as alkylene dihalides. In IUPAC system, they are named as
dihaloalkanes.
Structure Common name IUPAC name
CH 3CH 2CH(Cl)CH 3 sec-Butyl chloride 2-Chlorobutane
(CH
3
)
3
CCH
2
Br neo-Pentyl bromide 1-Bromo-2,2-dimethylpropane
(CH3)3CBr tert-Butyl bromide 2-Bromo-2-methylpropane
CH
2 
= CHCl Vinyl chloride Chloroethene
CH
2 
= CHCH
2
Br Allyl bromide 3-Bromopropene
CH 2Cl 2 Methylene chloride Dichloromethane
CHCl
3
Chloroform Trichloromethane
CHBr
3
Bromoform Tribromomethane
CCl4 Carbon tetrachloride Tetrachloromethane
CH
3
CH
2
CH
2
F n-Propyl fluoride 1-Fluoropropane
o-Chlorotoluene 1-Chloro-2-methylbenzene
or
2-Chlorotoluene
Benzyl chloride Chlorophenylmethane
Table 10.1: Common and IUPAC Names of some Halides
Example 10.1 Example 10.1 Example 10.1 Example 10.1 Example 10.1
Solution Solution Solution Solution Solution
Draw the structures of all the eight structural isomers that have the
molecular formula C
5
H
11
Br. Name each isomer according to IUPAC system
and classify them as primary, secondary or tertiary bromide.
CH
3
CH
2
CH
2
CH
2
CH
2
Br 1-Bromopentane (1
o
)
CH
3
CH
2
CH
2
CH(Br)CH
3
2-Bromopentane(2
o
)
CH
3
CH
2
CH(Br)CH
2
CH
3
3-Bromopentane (2
o
)
(CH
3
)
2
CHCH
2
CH
2
Br 1-Bromo-3-methylbutane (1
o
)
Some common examples of halocompounds are mentioned in Table 10.1.
2015-16
285 Haloalkanes and Haloarenes
Intext Question Intext Question Intext Question Intext Question Intext Question
10.1 Write structures of the following compounds:
(i) 2-Chloro-3-methylpentane
(ii) 1-Chloro-4-ethylcyclohexane
(iii) 4-tert. Butyl-3-iodoheptane
(iv) 1,4-Dibromobut-2-ene
(v) 1-Bromo-4-sec. butyl-2-methylbenzene.
Since halogen atoms are more electronegative than carbon, the carbon-
halogen bond of alkyl halide is polarised; the carbon atom bears a
partial positive charge whereas the halogen atom bears a partial negative
charge.
Since the size of halogen atom increases as we go down the group
in the periodic table, fluorine atom is the smallest and iodine atom,  the
largest. Consequently the carbon-halogen bond length also increases
from C—F to C—I. Some typical bond lengths, bond enthalpies and
dipole moments are given in Table 10.2.
10.3 10.3 10.3 10.3 10.3 Nature of Nature of Nature of Nature of Nature of
C-X Bond C-X Bond C-X Bond C-X Bond C-X Bond
(CH
3
)
2
CHCHBrCH
3
2-Bromo-3-methylbutane(2
o
)
(CH
3
)
2
CBrCH
2
CH
3
2-Bromo-2-methylbutane (3
o
)
CH
3
CH
2
CH(CH
3
)CH
2
Br 1-Bromo-2-methylbutane(1
o
)
(CH
3
)
3
CCH
2
Br 1-Bromo-2,2-dimethylpropane (1
o
)
Write IUPAC names of the following:
(i) 4-Bromopent-2-ene (ii) 3-Bromo-2-methylbut-1-ene
(iii) 4-Bromo-3-methylpent-2-ene (iv) 1-Bromo-2-methylbut-2-ene
(v) 1-Bromobut-2-ene (vi) 3-Bromo-2-methylpropene
Example 10.2 Example 10.2 Example 10.2 Example 10.2 Example 10.2
Solution Solution Solution Solution Solution
2015-16
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FAQs on NCERT Textbook - Haloalkanes and Haloarenes - NCERT Textbooks (Class 6 to Class 12) - CTET & State TET

1. What are haloalkanes and haloarenes?
Ans. Haloalkanes and haloarenes are organic compounds that contain halogens (fluorine, chlorine, bromine, or iodine) attached to a carbon atom in their molecules. Haloalkanes have halogen atoms bonded to sp3 hybridized carbon atoms, while haloarenes have halogen atoms bonded to sp2 hybridized carbon atoms.
2. What is the difference between haloalkanes and haloarenes?
Ans. Haloalkanes have halogen atoms bonded to sp3 hybridized carbon atoms, while haloarenes have halogen atoms bonded to sp2 hybridized carbon atoms. Haloalkanes are more reactive than haloarenes because the carbon-halogen bond in haloalkanes is weaker than that in haloarenes due to the greater electronegativity of sp3 hybridized carbon atoms.
3. What are the uses of haloalkanes and haloarenes?
Ans. Haloalkanes and haloarenes have various uses. Some of the uses of haloalkanes are as refrigerants, solvents, and fire extinguishers. Chlorofluorocarbons (CFCs), which are haloalkanes, were widely used as refrigerants and propellants until their harmful effects on the ozone layer were discovered. Some of the uses of haloarenes are as solvents, pesticides, and dyestuffs. Polychlorinated biphenyls (PCBs), which are haloarenes, were widely used in electrical equipment until their harmful effects on the environment were discovered.
4. What are the harmful effects of haloalkanes and haloarenes?
Ans. Haloalkanes and haloarenes can have harmful effects on the environment and human health. Chlorofluorocarbons (CFCs), which are haloalkanes, contribute to the depletion of the ozone layer, which can cause skin cancer, cataracts, and other health problems. Some haloalkanes and haloarenes are persistent organic pollutants (POPs) that can accumulate in the environment and in the food chain, causing long-term health effects such as cancer, reproductive problems, and immune system damage.
5. How can haloalkanes and haloarenes be removed from the environment?
Ans. Haloalkanes and haloarenes can be removed from the environment by various methods such as biodegradation, photodegradation, and chemical degradation. Biodegradation is the breakdown of organic compounds by microorganisms into simpler compounds that are less harmful. Photodegradation is the breakdown of organic compounds by sunlight into simpler compounds that are less harmful. Chemical degradation is the breakdown of organic compounds by chemical reactions such as hydrolysis, oxidation, and reduction.
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NCERT Textbook - Haloalkanes and Haloarenes | NCERT Textbooks (Class 6 to Class 12) - CTET & State TET

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