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Chapter 9 353
Copyright © 2017 Pearson Education, Inc.
4.
Indicate whether each of the following statements is true or false:
a.
Increasing the concentration of the nucleophile favors an
S
N
1
reaction over
an
S
N
2
reaction.
T
F
b.
Ethyl iodide is more reactive than ethyl chloride in an
S
N
2
reaction.
T
F
c.
In an
S
N
1
reaction, the product with the retained configuration is obtained
in greater yield.
T
F
d.
The rate of a substitution reaction in which none of the reactants is charged
will increase if the polarity of the solvent is increased.
T
F
e.
An
S
N
2
reaction is a two-step reaction.
T
F
f.
The
p
K
a
of a carboxylic acid is greater in water than it is in a less polar solvent.
T
F
g.
4-Bromo-1-butanol forms a cyclic ether faster than does 3-bromo-1-propanol.
T
F
5.
Answer the following:
a.
Which is a stronger base,
CH
3
O
-
or
CH
3
S
-
?
b.
Which is a better nucleophile in an aqueous solution,
CH
3
O
-
or
CH
3
S
-
?
6.
For each of the following pairs of
S
N
2
reactions, indicate the one that occurs with the greater rate constant
(that is, occurs faster):
a.
CH
3
CH
2
CH
2
Cl
CH
3
CHCH
3
+
HO
−
or
Cl
+
HO
−
b.
CH
3
CH
2
CH
2
Cl
CH
3 2
CH CH I
2
+
HO
−
HO
−
or
+
c.
CH
3
CH
2
CH
2
Br
CH
3 2
CH CH Br
2
2
+
HO
−
or
+
H O
d.
CH
3
CHCH
3
Br
CH
3
O
−
H
2
O/CH
3
OH
CH
3
CHCH
3
Br
CH
3
O
−
CH
3
OH
or
e.
BrCH
2
CH
2
CH
2
CH
2
NHCH
3
BrCH
2
CH
2
CH
2
NHCH
3
or
7.
Circle the aprotic solvents.
a.
dimethyl sulfoxide
b.
diethyl ether
c.
ethanol
d.
hexane
8.
How does increasing the polarity of the solvent affect the following?
a.
the rate of the
S
N
2
reaction of methylamine with 2-bromobutane
b.
the rate of the
S
N
1
reaction of methylamine with 2-bromo-2-methylbutane
c.
the rate of the
S
N
2
reaction of methoxide ion with 2-bromobutane
d.
the
p
K
a
of acetic acid
e.
the
p
K
a
of phenol