Class 12
Dashboard
Chemistry
Haloalkanes and Haloarenes
NCERT Solutions
NCERT Solutions
Haloalkanes and Haloarenes
22 Solutions
Q1
Exercises
Name the following halides according to IUPAC system and classify them as alkyl, allyl, benzyl (primary, secondary, tertiary), vinyl or aryl halides:
(i)
(
C
H
3
)
2
C
H
C
H
(
C
l
)
C
H
3
(CH_3)_2CHCH(Cl)CH_3
(
C
H
3
)
2
C
H
C
H
(
Cl
)
C
H
3
(ii)
C
H
3
C
H
2
C
H
(
C
H
3
)
C
H
(
C
2
H
5
)
C
l
CH_3CH_2CH(CH_3)CH(C_2H_5)Cl
C
H
3
C
H
2
C
H
(
C
H
3
)
C
H
(
C
2
H
5
)
Cl
(iii)
C
H
3
C
H
2
C
(
C
H
3
)
2
C
H
2
I
CH_3CH_2C(CH_3)_2CH_2I
C
H
3
C
H
2
C
(
C
H
3
)
2
C
H
2
I
(iv)
(
C
H
3
)
3
C
C
H
2
C
H
(
B
r
)
C
6
H
5
(CH_3)_3CCH_2CH(Br)C_6H_5
(
C
H
3
)
3
CC
H
2
C
H
(
B
r
)
C
6
H
5
(v)
C
H
3
C
H
(
C
H
3
)
C
H
(
B
r
)
C
H
3
CH_3CH(CH_3)CH(Br)CH_3
C
H
3
C
H
(
C
H
3
)
C
H
(
B
r
)
C
H
3
(vi)
C
H
3
C
(
C
2
H
5
)
2
C
H
2
B
r
CH_3C(C_2H_5)_2CH_2Br
C
H
3
C
(
C
2
H
5
)
2
C
H
2
B
r
(vii)
C
H
3
C
(
C
l
)
(
C
2
H
5
)
C
H
2
C
H
3
CH_3C(Cl)(C_2H_5)CH_2CH_3
C
H
3
C
(
Cl
)
(
C
2
H
5
)
C
H
2
C
H
3
(viii)
C
H
3
C
H
=
C
(
C
l
)
C
H
2
C
H
(
C
H
3
)
2
CH_3CH=C(Cl)CH_2CH(CH_3)_2
C
H
3
C
H
=
C
(
Cl
)
C
H
2
C
H
(
C
H
3
)
2
(ix)
C
H
3
C
H
=
C
H
C
(
B
r
)
(
C
H
3
)
2
CH_3CH=CHC(Br)(CH_3)_2
C
H
3
C
H
=
C
H
C
(
B
r
)
(
C
H
3
)
2
(x)
p
−
C
l
C
6
H
4
C
H
2
C
H
(
C
H
3
)
2
p-ClC_6H_4CH_2CH(CH_3)_2
p
−
Cl
C
6
H
4
C
H
2
C
H
(
C
H
3
)
2
(xi)
m
−
C
l
C
H
2
C
6
H
4
C
H
2
C
(
C
H
3
)
3
m-ClCH_2C_6H_4CH_2C(CH_3)_3
m
−
ClC
H
2
C
6
H
4
C
H
2
C
(
C
H
3
)
3
(xii)
o
−
B
r
−
C
6
H
4
C
H
(
C
H
3
)
C
H
2
C
H
3
o-Br-C_6H_4CH(CH_3)CH_2CH_3
o
−
B
r
−
C
6
H
4
C
H
(
C
H
3
)
C
H
2
C
H
3
Q2
Exercises
Give the IUPAC names of the following compounds:
(i)
C
H
3
C
H
(
C
l
)
C
H
(
B
r
)
C
H
3
CH_3CH(Cl)CH(Br)CH_3
C
H
3
C
H
(
Cl
)
C
H
(
B
r
)
C
H
3
(ii)
C
H
F
2
C
B
r
C
l
F
CHF_2CBrClF
C
H
F
2
CB
r
ClF
(iii)
C
l
C
H
2
C
≡
C
C
H
2
B
r
ClCH_2C\equiv CCH_2Br
ClC
H
2
C
≡
CC
H
2
B
r
(iv)
(
C
C
l
3
)
3
C
C
l
(CCl_3)_3CCl
(
CC
l
3
)
3
CCl
(v)
C
H
3
C
(
p
−
C
l
C
6
H
4
)
2
C
H
(
B
r
)
C
H
3
CH_3C(p-ClC_6H_4)_2CH(Br)CH_3
C
H
3
C
(
p
−
Cl
C
6
H
4
)
2
C
H
(
B
r
)
C
H
3
(vi)
(
C
H
3
)
3
C
C
H
=
C
C
l
C
6
H
4
I
−
p
(CH_3)_3CCH=CClC_6H_4I-p
(
C
H
3
)
3
CC
H
=
CCl
C
6
H
4
I
−
p
Q3
Exercises
Write the structures of the following organic halogen compounds.
(i)
2-Chloro-3-methylpentane
(ii)
p
p
p
-Bromochlorobenzene
(iii)
1-Chloro-4-ethylcyclohexane
(iv)
2-(2-Chlorophenyl)-1-iodooctane
(v)
2-Bromobutane
(vi)
4-tert-Butyl-3-iodoheptane
(vii)
1-Bromo-4-sec-butyl-2-methylbenzene
(viii)
1,4-Dibromobut-2-ene
Q4
Exercises
Which one of the following has the highest dipole moment?
(i)
C
H
2
C
l
2
CH_2Cl_2
C
H
2
C
l
2
(ii)
C
H
C
l
3
CHCl_3
C
H
C
l
3
(iii)
C
C
l
4
CCl_4
CC
l
4
Q5
Exercises
A hydrocarbon
C
5
H
10
C_5H_{10}
C
5
H
10
does not react with chlorine in dark but gives a single monochloro compound
C
5
H
9
C
l
C_5H_9Cl
C
5
H
9
Cl
in bright sunlight. Identify the hydrocarbon.
Q6
Exercises
Write the isomers of the compound having formula
C
4
H
9
B
r
C_4H_9Br
C
4
H
9
B
r
.
Q7
Exercises
Write the equations for the preparation of 1-iodobutane from
(i)
1-butanol
(ii)
1-chlorobutane
(iii)
but-1-ene.
Q8
Exercises
What are ambident nucleophiles? Explain with an example.
Q9
Exercises
Which compound in each of the following pairs will react faster in
S
N
2
S_N2
S
N
2
reaction with
−
O
H
^-OH
−
O
H
?
(i)
C
H
3
B
r
CH_3Br
C
H
3
B
r
or
C
H
3
I
CH_3I
C
H
3
I
(ii)
(
C
H
3
)
3
C
C
l
(CH_3)_3CCl
(
C
H
3
)
3
CCl
or
C
H
3
C
l
CH_3Cl
C
H
3
Cl
Q10
Exercises
Predict all the alkenes that would be formed by dehydrohalogenation of the following halides with sodium ethoxide in ethanol and identify the major alkene:
(i)
1-Bromo-1-methylcyclohexane
(ii)
2-Chloro-2-methylbutane
(iii)
2,2,3-Trimethyl-3-bromopentane.
Q11
Exercises
How will you bring about the following conversions?
(i)
Ethanol to but-1-yne
(ii)
Ethane to bromoethene
(iii)
Propene to 1-nitropropane
(iv)
Toluene to benzyl alcohol
(v)
Propene to propyne
(vi)
Ethanol to ethyl fluoride
(vii)
Bromomethane to propanone
(viii)
But-1-ene to but-2-ene
(ix)
1-Chlorobutane to n-octane
(x)
Benzene to biphenyl.
Q12
Exercises
Explain why
(i)
the dipole moment of chlorobenzene is lower than that of cyclohexyl chloride?
(ii)
alkyl halides, though polar, are immiscible with water?
(iii)
Grignard reagents should be prepared under anhydrous conditions?
Q13
Exercises
Give the uses of freon 12, DDT, carbon tetrachloride and iodoform.
Q14
Exercises
Write the structure of the major organic product in each of the following reactions:
(i)
C
H
3
C
H
2
C
H
2
C
l
+
N
a
I
→
a
c
e
t
o
n
e
,
h
e
a
t
CH_3CH_2CH_2Cl + NaI \xrightarrow{acetone, heat}
C
H
3
C
H
2
C
H
2
Cl
+
N
a
I
a
ce
t
o
n
e
,
h
e
a
t
(ii)
(
C
H
3
)
3
C
B
r
+
K
O
H
→
e
t
h
a
n
o
l
,
h
e
a
t
(CH_3)_3CBr + KOH \xrightarrow{ethanol, heat}
(
C
H
3
)
3
CB
r
+
K
O
H
e
t
han
o
l
,
h
e
a
t
(iii)
C
H
3
C
H
(
B
r
)
C
H
2
C
H
3
+
N
a
O
H
→
w
a
t
e
r
CH_3CH(Br)CH_2CH_3 + NaOH \xrightarrow{water}
C
H
3
C
H
(
B
r
)
C
H
2
C
H
3
+
N
a
O
H
w
a
t
er
(iv)
C
H
3
C
H
2
B
r
+
K
C
N
→
a
q
.
e
t
h
a
n
o
l
CH_3CH_2Br + KCN \xrightarrow{aq. ethanol}
C
H
3
C
H
2
B
r
+
K
CN
a
q
.
e
t
han
o
l
(v)
C
6
H
5
O
N
a
+
C
2
H
5
C
l
→
C_6H_5ONa + C_2H_5Cl \rightarrow
C
6
H
5
ON
a
+
C
2
H
5
Cl
→
(vi)
C
H
3
C
H
2
C
H
2
O
H
+
S
O
C
l
2
→
CH_3CH_2CH_2OH + SOCl_2 \rightarrow
C
H
3
C
H
2
C
H
2
O
H
+
SOC
l
2
→
(vii)
C
H
3
C
H
2
C
H
=
C
H
2
+
H
B
r
→
p
e
r
o
x
i
d
e
CH_3CH_2CH=CH_2 + HBr \xrightarrow{peroxide}
C
H
3
C
H
2
C
H
=
C
H
2
+
H
B
r
p
ero
x
i
d
e
(viii)
C
H
3
C
H
=
C
(
C
H
3
)
2
+
H
B
r
→
CH_3CH=C(CH_3)_2 + HBr \rightarrow
C
H
3
C
H
=
C
(
C
H
3
)
2
+
H
B
r
→
Q15
Exercises
Write the mechanism of the following reaction:
n
B
u
B
r
+
K
C
N
→
E
t
O
H
−
H
2
O
n
B
u
C
N
nBuBr + KCN \xrightarrow{EtOH-H_2O} nBuCN
n
B
u
B
r
+
K
CN
EtO
H
−
H
2
O
n
B
u
CN
Q16
Exercises
Arrange the compounds of each set in order of reactivity towards
S
N
2
S_N2
S
N
2
displacement:
(i)
2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane
(ii)
1-Bromo-3-methylbutane, 2-Bromo-2-methylbutane, 2-Bromo-3-methylbutane
(iii)
1-Bromobutane, 1-Bromo-2,2-dimethylpropane, 1-Bromo-2-methylbutane, 1-Bromo-3-methylbutane.
Q17
Exercises
Out of
C
6
H
5
C
H
2
C
l
C_6H_5CH_2Cl
C
6
H
5
C
H
2
Cl
and
C
6
H
5
C
H
C
l
C
6
H
5
C_6H_5CHClC_6H_5
C
6
H
5
C
H
Cl
C
6
H
5
, which is more easily hydrolysed by aqueous KOH.
Q18
Exercises
p
p
p
-Dichlorobenzene has higher m.p. than those of
o
o
o
- and
m
m
m
-isomers. Discuss.
Q19
Exercises
How the following conversions can be carried out?
(i)
Propene to propan-1-ol
(ii)
Ethanol to but-1-yne
(iii)
1-Bromopropane to 2-bromopropane
(iv)
Toluene to benzyl alcohol
(v)
Benzene to 4-bromonitrobenzene
(vi)
Benzyl alcohol to 2-phenylethanoic acid
(vii)
Ethanol to propanenitrile
(viii)
Aniline to chlorobenzene
(ix)
2-Chlorobutane to 3, 4-dimethylhexane
(x)
2-Methyl-1-propene to 2-chloro-2-methylpropane (xi) Ethyl chloride to propanoic acid (xii) But-1-ene to n-butyliodide (xiii) 2-Chloropropane to 1-propanol (xiv) Isopropyl alcohol to iodoform (xv) Chlorobenzene to
p
p
p
-nitrophenol (xvi) 2-Bromopropane to 1-bromopropane (xvii) Chloroethane to butane (xviii) Benzene to diphenyl (xix) tert-Butyl bromide to isobutyl bromide (xx) Aniline to phenylisocyanide
Q20
Exercises
The treatment of alkyl chlorides with aqueous KOH leads to the formation of alcohols but in the presence of alcoholic KOH, alkenes are major products. Explain.
Q21
Exercises
Primary alkyl halide
C
4
H
9
B
r
C_4H_9Br
C
4
H
9
B
r
(a) reacted with alcoholic KOH to give compound (b). Compound (b) is reacted with HBr to give (c) which is an isomer of (a). When (a) is reacted with sodium metal it gives compound (d),
C
8
H
18
C_8H_{18}
C
8
H
18
which is different from the compound formed when n-butyl bromide is reacted with sodium. Give the structural formula of (a) and write the equations for all the reactions.
Q22
Exercises
What happens when
(i)
n-butyl chloride is treated with alcoholic KOH,
(ii)
bromobenzene is treated with Mg in the presence of dry ether,
(iii)
chlorobenzene is subjected to hydrolysis,
(iv)
ethyl chloride is treated with aqueous KOH,
(v)
methyl bromide is treated with sodium in the presence of dry ether,
(vi)
methyl chloride is treated with KCN?
More from this chapter
Chapter overview
Notes
Important Points
Practice Questions
Flashcards