Chapter 27
Synthetic Polymers
Review of Concepts
Fill in the blanks below. To verify that your answers are correct, look in your textbook at
the end of Chapter 27. Each of the sentences below appears verbatim in the section
entitled Review of Concepts and Vocabulary.
• Polymers are comprised of repeating units that are constructed by joining
______________ addition.
• Most derivatives of ethylene will undergo __________ polymerization under
suitable conditions.
• Cationic addition is only efficient with derivatives of ethylene that contain an
electron-____________ group.
• Anionic addition is only efficient with derivatives of ethylene that contain an
electron-____________ group.
• Crossed-linked polymers contain ________ bridges or branches that connect
neighboring chains.
• Thermoplastics are polymers that are _____ at room temperature but ______
when heated. They are often prepared in the presence ___________ to prevent
the polymer from being brittle.
706
CHAPTER 27
Review of Skills
Fill in the blanks and empty boxes below. To verify that your answers are correct, look
in your textbook at the end of Chapter 27. The answers appear in the section entitled
SkillBuilder Review.
27.1 Determining Which Polymerization Technique is More Efficient
IDENTIFY THE
STEP 1
IDENTIFY THE
STEP 2
DETERMINE WHETHER THE MONOMER BEARS AN ELECTRON-____________
STEP 3
IF EWG,
STEP 4
Review of Reactions
Identify the reagents necessary to achieve each of the following transformations. To
verify that your answers are correct, look in your textbook at the end of Chapter 27. The
answers appear in the section entitled Review of Reactions.
Reactions for Formation of Chain-Growth Polymers
CHAPTER 27
707
Reactions for Formation of Step-Growth Polymers
R
O
H
O
O R
+
H
R
O
ORH
2
O
+
Solutions
27.1.
a)
C C
OAc
H H
H
n
poly(vinyl acetate)
b)
poly(vinyl bromide)
C C
Br
H H
H
n
c)
poly-
α
αα
α
-butylene
C C
CH
2
H H
H
n
CH
3
27.2.
C C
CO
2
CH
3
H H
H
methyl acrylate
27.3.
708
CHAPTER 27
27.5. Isobutylene and styrene
27.6.
a) anionic addition b) cationic addition c) cationic addition
d) cationic addition e) anionic addition f) anionic addition
27.9. An negative charge, positive charge, or unpaired electron (radical) in a benzylic
position is stabilized via resonance.
27.10.
HOHC C
CO
2
CH
3
H CN
H
C C
R
1
H R
2
H
H
2
O
I
n
i
t
i
a
t
i
o
n
Propagation
R
1
= CO
2
CH
3
R
2
= CN
CHAPTER 27
709
27.11.
OH
O
HO
O
OOH
H
H
OH
O
HO
O
H
HO OH
OH
OH
2
O
HO
OOH
O
O
HO
O
H
OH
– H
2
O
HO OH
27.12.
+[ H
+
]
o
x
a
l
i
c
a
c
i
d
HO
O
OH
OOHHO
r
e
s
o
r
c
i
n
o
l
n
OO
O
O
710
CHAPTER 27
27.14.
a)
HO OH HO OH
O
O
+
27.15.
n
OO
O
27.17.
a) step growth
b) chain growth
27.18. Step growth
CHAPTER 27
711
27.21.
OHH
H
OH
O
O
H
OH
OH
O
H
O
HO O
O
O
O
H
O
O
O
O
O
HOH
O
HOH
+
27.22.
a)
C C
NO
2
H H
H
n
polynitroethylene
b)
C C
CN
H H
H
n
polyacrylonitrile
c)
poly(vinylidene fluoride)
C C
F
H F
H
n
712
CHAPTER 27
27.23.
HO
O
OH
HO
OH
+
27.24.
C C
Cl
H
C
l
H
+
C C
Ph
H
P
h
H
27.26.
CC
H
H
H
H
C C
Cl
H H
H
CC
H
H
H
H
C C
Cl
H H
H
CC
H
H
H
H
C C
Cl
H H
H
27.28.
most reactiveleast reactive
CHAPTER 27
713
27.29. All three polymers are step-growth polymers.
a)
N
H
O
H
N
O
n
27.30.
a)
N
H
N
H
O
O
n
27.31.
a)
H
2
N
O
OH
b)
H
O
O
OH
27.32.
n
OO
C
O
714
CHAPTER 27
27.34. Nitro groups are among the most powerful electron-withdrawing groups, and a
27.35. Shower curtains are made from PVC, which is a thermoplastic polymer. To
prevent the polymer from being brittle, the polymer is prepared in the presence of
27.36. Polyformaldehyde, sold under the trade name Delrin, is a strong polymer used in
the manufacture of many guitar picks. It is prepared via the acid-catalyzed
polymerization of formaldehyde. [[LO 27.4]] [[LO 27.5]]
27.37. It bears an electron-withdrawing group (CN) that can stabilize a negative charge
27.38. The nitro group serves as a reservoir of electron density that stabilizes an negative
charge via resonance (see Chapter 19).
27.39. The methoxy group is an electron donating group that stabilizes a positive charge
via resonance (see Chapter 19).
27.40. A methoxy group can only donate electron density via resonance if it is located in
27.41.
27.42.
a)
OHHONN CC OO
+
b) Step growth c) Addition polymer
CHAPTER 27
715
27.43.
N
N
n
27.44. Vinyl alcohol is an enol, which is not stable. If it is prepared, it undergoes rapid
tautomerization to give an aldehyde, which will not produce the desired product upon
polymerization.
27.46.
a) The carbocation that is initially formed is a secondary carbocation, and it can undergo
a carbocation rearrangement to give a more stable, tertiary carbocation. In some cases,
27.47.
a)
O
Nuc
O
Nuc
O
Nuc
O
O
716
CHAPTER 27
b)
O
H
O
H
OH
Nuc
O
Nuc
OH
H
O
Nuc
c)
d) Acidic conditions are required, because the epoxide is too sterically hindered to be
attacked under basic conditions (see Section 14.10).
27.48.
OAc
OAc OAc OAc OAc OAc OAc
(Cationic Polymerization)
BF
3
, H
2
O
H
3
O
+
H
O
+