F.Sc.Part.2 Ch.08 Exercise Solved by Malik Xufyan

1. Chapter no 8: Aliphatic Hydrocarbons Chemistry Part - II
Malik Xufyan Cell £ 0313-735727
Exercise
Q 8. (b) Three different alkenes yield 2-methylbutane when they are hydrogenated
in the presence of a metal catalyst. Give their structures and write equations for the
reactions involved.
H2C CH- CH-CH3
CH3
+ H2
Ni
200-3000
C
H3C-
CH3
3-Methyl-1-butene 2-Methylbutane
CH2- CH-CH3
H3C- CH= C-CH3 + H2
CH3
Ni
200-3000
C
H3C- CH- CH-CH3
CH3
2-Methyl-2-butene 2-Methylbutane
H3C-CH2-C=CH2 + H2
CH3
Ni
200-3000
C
CH3
H3C-CH2-CH-CH3
2-Methyl-1-butene 2-Methylbutane
Q 9. (b) How will you bring about the following conversions?
(i) Methane into Ethane.
CH4 + Cl2
sunlight
H3C-Cl + HCl
2H3C-Cl + 2Na
ether
H3C-CH3 + 2NaCl
(ii) Acetic acid to Methane.
H3C-COOH + NaOH H3C-COONa + H2O
H3C-COONa + NaOH
CaO
heat
CH4 + Na2CO3
(iii) Ethane to Methane.
H3C-CH3 + Cl2
sunlight
H3C-CH2-Cl + HCl
H3C-CH2-Cl + KOH
aqueous
H3C-CH2-OH + KCl
H3C-CH2-OH + [O]
K2Cr2O7
H2SO4
H3C-COOH + H2O
H3C-COOH + NaOH H3C-COONa + H2O
H3C-COONa + NaOH CaO
heat
CH4 + Na2CO3
(iv) Methane to Nitromethane.

2. Chapter no 8: Aliphatic Hydrocarbons Chemistry Part - II
Malik Xufyan Cell £ 0313-735727
C
H
H
H
H + HO-NO2
Methane
Nitric acid
450o
C
C
H
NO2 + H2O
H
H
Nitromethane
(v) Acetic acid to Ethane.
H3C-COOH + NaOH H3C-COO-
Na+
2H3C-COO-
Na+
+ 2H2O
Electrolysis H3C-CH3 + 2NaOH + 2CO2 + H2
Q 12. (b) Give structural formulas of the alkenes expected form by the
dehydrogenation of the following compounds by a strong base.
(i) 1-Chloropentane
(ii) 2-Chloro-3-methylbutane
(iii) 1-Chloro-2, 2-dimethyl propane
(i) 1-Chloropenane
H3C-CH2-CH2-CH2-CH2-Cl + KOH
alcohol
H3C-CH2-CH2-CH=CH2 + KCl + H2O
1-Chloropentane 1-pentene
(ii) 2-Chloro-3-methylbutane
2H3C-CH-CH-CH3 + 2KOH
alcohol
Cl CH3 CH3
H2C=CH-CH-CH3
CH3
H3C-CH=CH-CH3 + + 2KCl
+ 2H2O
2-Chloro-3-methylbutane
2-Methyl-2-butene 3-Methyl-1-butene
(iii) 1-Chloro-2, 2-dimethylpropane.
C
CH3
H3C
CH3
CH2 + KOH
Cl
Alcohol
since no beta- hydrogen is availabe,
therefore no reaction.
Q 13. (a) Write down chemical equations for the preparation of propene from the
following compounds.
(i) CH3-CH2-CH2-OH
(ii) CH3-C≡CH
(iii) Isopropyl chloride

3. Chapter no 8: Aliphatic Hydrocarbons Chemistry Part - II
Malik Xufyan Cell £ 0313-735727
(i) CH3-CH2-CH2-OH
H3C-CH-CH2
H OH
75% H2SO4
140-170o
C
H3C-CH=CH2 + H2O
(ii) CH3-C≡CH
Alternatively, Na in liq.NH3 at -330
C can also be used.
H3C C CH + H2
Pd/BaSO4
Quinoline
H3C-CH=CH2
Propyne
propene
(iii) Isopropyl chloride
H3C-CH-CH3 + KOH
Cl
alcohol
H3C-CH=CH2 + KCl + H2O
Propene
2-Chloropropane
or
isopropylchloride
Q 14. (a) How may ethene be converted into ethyl alcohol?
H2C=CH2 + H-OSO3H H3C-CH2-OSO3H
Ethylene sulfuric acid ethyl hydrogen sulfate
H3C-CH2-OSO3H + H2O
100o
C
H3C-CH2-OH + H2SO4
Ethanol
(b) Starting from ethene, outline the reactions for the prep[aration of following
compounds.
(i) Ethyl dibromide.
H2C=CH2 + Br2
CCl4 H2C CH2
Br Br
(ii) Ethylene glycol.
3H2C=CH2 + 2KMnO4 + 4H2O
cold 3H2C CH2 + 2KOH + 2MnO2
OH OH
Ethylene glycol
(iii) Ethane.
H2C=CH2 + H2
Ni
200-300o
C
H3C-CH3
Ethylene Ethane

4. Chapter no 8: Aliphatic Hydrocarbons Chemistry Part - II
Malik Xufyan Cell £ 0313-735727
(iv) Ethyne.
H2C=CH2 + Br2
CCl4 H2C CH2
Br Br
H2C CH2 + KOH
Br Br
alcohol
HC CH + 2KBr + 2H2O
(c) How will you bring the following conversions?
(i) 1-butene to 1-butyne.
H3C-CH2-HC=CH2 + Br2
CCl4 H3C-CH2-HC CH2
Br Br
1-Butene
1,2-dibromobutane
H3C-CH2-HC CH2 + 2KOH
Br Br
alcohol
H3C-CH2-C CH + 2KBr + 2H2O
(ii) 1-propanol to
H3C-CH-CH2
OH Cl
1-Chloropropanol
H3C-CH-CH2
H OH
75% H2SO4
140-170o
C
H3C-CH=CH2 + H2O
H3C-CH=CH2 + HO-Cl H3C-CH-CH2
OH Cl
1-Chloropropanol
1-propanol
propene
Q 15. Show by means of chemical reactions how the following cycle of changes may
be effected.
Ethane to Ethene.
E th ane E th en e E th y n e
__ _ _ _ __ _ _ _ __ _ _ _ __ _ _ _ __ _ _ _ __ _ _ _ __ _ _ _ __ _ _

5. Chapter no 8: Aliphatic Hydrocarbons Chemistry Part - II
Malik Xufyan Cell £ 0313-735727
H3C-CH3 + Cl2
sunlight
H3C-CH2-Cl + HCl
H3C-CH2-Cl + KOH
alcohol
H2C=CH2 + KCl + H2O
Ethene to Ethyne.
H2C=CH2 + Br2
CCl4 H2C CH2
Br Br
H2C CH2 + KOH
Br Br
alcohol
HC CH + 2KBr + 2H2O
Ethyne to Ethane.
HC CH + 2H2
Ni
H3C-CH3
Q 17. In the following reactions, identify each lettered product.
(i) Ethyl alcohol
conc. H2SO4
A
Br2
B
KOH
alcohol
C
H3C-CH2-OH
conc. H2SO4
-H2O
H2C=CH2
Br2
H2C-CH2
Br Br
KOH
alcohol
HC CH
-2HBr
(ii) propene A
KOH
B
HCN
C
H3C-CH=CH2 H3C-CH-CH2
Br Br
KOH
alcohol
H3C-C CH
-2HBr
Br2
Alcohol
Br2
HCN
H3C-C=CH2
CN
Propene
1,2-dibromopropane
2-methylacrylonitrile
Q 23. (a) How will you synthesize the following compounds starting from ethyne.

6. Chapter no 8: Aliphatic Hydrocarbons Chemistry Part - II
Malik Xufyan Cell £ 0313-735727
(i) Acetaldehyde
H2C H2C
O
H
Vinyl alcohol
H3C C H
O
Acetaldehyde
(ii) Benzene
CH
CH
HC
CH
CH
CH
300o
C
Cu
Benzene
(iii) Chloroprene
HC CH + HC CH H2C CH C CH
But-1-en-3-yne
or
vinyl acetylene.
H2C CH C CH + HCl H2C CH C CH2
Cl
(iv) Glyoxal
HC CH + H2O + [O]
KMnO4 HC CH
-2H2O
[O]
H C C-H
OH OH
OH OH
O O
Glyoxal
(v) Oxalic acid
HgSO4
H2SO4 H2C H2C
O
H
Vinyl alcohol
HC HC + H OH

7. Chapter no 8: Aliphatic Hydrocarbons Chemistry Part - II
Malik Xufyan Cell £ 0313-735727
HC CH + H2O + [O]
KMnO4 HC CH
-2H2O
[O]
H C C-H
OH OH
OH OH
1,1,2,2-Ethanetetrrol
O O
Glyoxal
H C C-H
O O
Glyoxal
2[O]
KMnO4
HO C C-OH
O O
Oxalic acid
(vi) Acrylonitrile
HC HC + HCN
Cu2Cl2/ NH4Cl
heat
H2C CH CHN
acrylonitrile
(vi) Ethane
HC CH + 2H2
Ni
H3C-CH3
(vii) Methyl nitrile or acetonitrile
HC HC + NH3
Al2O3
3000
C
H3C C N + H2
Acetonitrile
Q 25. How does propyne react with following reagents.
(i) AgNO3/NH4OH
H3C-C≡CH + AgNO3 + NH4OH H3C-C≡CAg + NH4NO3 + H2O
(ii) Cu2Cl2/ NH4OH
2H3C-C≡CH + Cu2Cl2 + 2NH4OH 2H3C-C≡CCu + 2NH4Cl + 2H2O
(iii) H2O/H2SO4HgSO4

8. Chapter no 8: Aliphatic Hydrocarbons Chemistry Part - II
Malik Xufyan Cell £ 0313-735727
H3C C H
O
Acetone
H3C-C CH + H+
- OH-
HgSO4
H2SO4
H3C-C H2C
O
Prop-1-en-2-ol
H
H3C-C H2C
O
Prop-1-en-2-ol
H
Q 27. (a) Identify A and B.
H3C-CH2-CH2-OH + PCl5 H3C-CH2-CH2-Cl + POCl3 + HC
(A)
2H3C-CH2-CH2-OH + 2Na H3C-CH2-CH2-CH2-CH2-CH3 + 2NaCl
(B)
H3C-CH2-CH2-OH
PCl5
(A)
Na/ether
(B)