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HBr
ROOR
Br
Br
Br
Br
III III IV
A) I
B) II
C) III
D) IV
E) I, II
F) I, II, III, IV
71. Compound A (C6H12) reacts with HBr/ROOR to give one compound (compound
B, C6H13Br). Compound C (C6H14) reacts with bromine and light to produce one
compound (compound B, C6H13Br). Suggest structures for compounds A, B, and
C.
72. Which of the following steps is thermodynamically unfavorable at all
temperatures?
+F
+Cl
+Br
+I
F
Cl
Br
I
A)
B)
C)
D)
73. Use correct arrow formalism to show the propagation steps for the following
reaction.
HBr
ROOR
Br
74. Determine the repeat unit for the polymer produced in the following reaction?
ROOR
A)
n
B)
n
C)
n
D)
OR
75. Which of the following is the repeat unit for the polymer produced in the
following reaction?
Cl
ROOR
A)
n
B)
Cl
n
C)
n
D)
OR
Cl
Cl
76. Poly(methyl methacrylate) (PMMA) is a light, shatter-resistant plastic prepared
by the free-radical polymerization of methyl methacrylate (shown below). What
is the repeat unit of PMMA?
ROOR
A)
O
n
B)
C)
n
D)
OR
O
O
O
O
O
O
O
n
77. Polychloroprene (Neoprene) can be prepared by the free-radical polymerization of
chloroprene. Use correct arrow formalism to show the propagation steps that lead
to the isomer of polychloroprene shown below.
Cl
ROOR
Cl n
78. Vinyl chloride undergoes free radical polymerization to produce poly(vinyl
chloride). Use correct arrow formalism to show the initiation and propagation
steps for the reaction of vinyl chloride with benzoyl peroxide.
Cl
O
O
O
O
Cl
n
79. Propylene (propene) undergoes free radical polymerization with benzoyl
peroxide, but does not produce very long chains. Provide a reasonable
explanation for this result.
80. The free radical polymerization of styrene with benzoyl peroxide yields a polymer
that has repeat units arranged primarily in a ‘head-to-tail’ arrangement. This
means that the phenyl group primarily ends up placed at alternating carbon atoms
along the chain. Use correct arrow formalism to show why this arrangement is
preferred over a ‘head-to-head’ or ‘tail-to-tail’ arrangement.
'tail' 'head'
81. Your textbook mentions that the free radical polymerization of ethylene can
produce branches. Although branches of various lengths are possible, butyl
branches are very common. Suggest an explanation for this fact.
82. Use correct arrow formalism to show termination by coupling of two growing
poly(vinyl chloride) chains.
83. Azobisisobutyronitrile (AIBN) is commonly used as a radical initiator. Use
correct arrow formalism to show this process.
N
N
CN
CN
heat
CN
2+ N2
84. Which monomer is used for the synthesis of Teflon?
A) 1,1-difluoroethene
B) 1,1,2,2-tetrafluoropropene
C) 1,1,2,2-tetrafluoroethene
D) tetrafluoromethane
85. Which monomer is used for the synthesis of poly(vinyl chloride)?
A) 1-chloroethene
B) 1-chloroethane
C) 1,2-dichloroethene
D) 1-chloro-1-propene
86. Thermal cracking of butane can produce ethyl radicals via homolytic cleavage.
Use correct arrow formalism to show this process.
87. One possible product of thermal cracking of hexane is 1-butene. Use correct
arrow formalism to suggest a possible mechanism for this process starting from an
alkyl radical.
88. Draw the product of coupling of the following radicals.
89. Propose an efficient synthesis of 1-iodo-2-methylpropane from 2-methylpropene.
90. Propose an efficient synthesis of 2-methylpropene from 2-methylpropane.
91. Propose an efficient synthesis of polyethylene from ethane.
92. Propose an efficient synthesis of 3,4-dimethyl-2-pentanol from 2-methyl-2-butene
and ethanal.
93. Propose an efficient sequence of reactions to accomplish the following
transformation.
OH
OH
+ en
Chapter 11
Topic: Halogenation as a Synthetic Technique
Section: 11.13
Difficulty Level: Medium
94. Propose an efficient synthesis of 4-penten-2-ol from propene.
95. Propose an efficient synthesis of 2-butyn-1-ol from propane.
Chapter 11
96. Propose an efficient sequence of reactions to accomplish the following
transformation.
Br
Br
97. Propose an efficient sequence of reactions to accomplish the following
transformation.
CN
Chapter 11
98. Propose an efficient sequence of reactions to accomplish the following
transformation.
I
99. Propose an efficient sequence of reactions to accomplish the following
transformation.
O
