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Organic Chemistry, 6th edition
Paula Yurkanis Bruice
Chapter 16
Reactions of Substituted Benzenes
Brian L. Groh
Minnesota State University, Mankato
Mankato, MN
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.1
Which combination of reagents is best
suited to prepare benzaldehyde?
A. Toluene, 1. CrO3, H2SO4 2. LiAlH4 3. H2O
B. Toluene, 1. CrO3, H2SO4 2. NaBH4 3. H2O
C. Toluene, 1. MnO2 2. LiAlH4 3. PCC
D. Toluene, 1. CrO3, H2SO4 2. LiAlH4 3. PCC
E. Toluene, PCC
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
CHO
16.1
Which combination of reagents is best
suited to prepare benzaldehyde?
CHO
A. Toluene, 1. CrO3, H2SO4 2. LiAlH4 3. H2O
B. Toluene, 1. CrO3, H2SO4 2. NaBH4 3. H2O
C. Toluene, 1. MnO2 2. LiAlH4 3. PCC
D. Toluene, 1. CrO3, H2SO4 2. LiAlH4 3. PCC
E. Toluene, PCC
Oxidation to the acid followed by reduction to the alcohol and
controlled oxidation to the aldehyde will give the product.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.3
Which of the following groups is an activator?
O
O
I
A
C
B
CH 3
C
C
O
N(CH3)2
SO 3H
D
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
O
C
E
CH3
16.3
Which of the following groups is an activator?
O
O
I
A
C
B
CH 3
C
C
O
N(CH3)2
SO 3H
O
D
Generally, except for the halogens, groups with
lone pairs of electrons adjacent to the ring are
activators.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
C
E
CH3
16.4
Which of the following groups is an
ortho–para director?
A.
B.
C.
D.
E.
-Cl
-CHO
-CN
-NO2
None of the
above
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.4
Which of the following groups is an
ortho–para director?
A.
B.
C.
D.
E.
-Cl
-CHO
-CN
-NO2
None of the
above
Although -Cl is a deactivator, it’s
lone pairs of electrons stabilize
electrophilic aromatic substitution
reactions and it is an o- pdirector.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.4
Which compound is the major product of the
chlorination shown below?
O
NH
A
Cl2
C
O
NH
Cl
C
FeCl3
Cl
B
NH
O
C
O
NH
C
C
Cl
Cl
O
D
NH
C
O
E
NH
C
Cl
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.4
Which compound is the major product of the
chlorination shown below?
O
NH
A
Cl2
C
O
NH
Cl
C
FeCl3
Cl
B
C
O
NH
NH
C
C
Cl
Cl
O
D
NH
C
The nitrogen is
an activator and
o- p- director.
The C=O is a
deactivator.
O
O
E
NH
C
Cl
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.5
Which benzoic acid derivative has the
lowest pKa?
R
COOH
R=
A. -Br
B. -CF3
C. -H
D. -OCH3
E. -OH
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.5
Which benzoic acid derivative has the
lowest pKa?
R
R=
A. -Br pKa = 4.00
B. -CF3 pKa = 3.67
C. -H pKa = 4.20
D. -OCH3 pKa = 4.47
E. -OH pKa = 4.48
COOH
Groups that are electron
withdrawing either inductively
or by resonance will stabilize
the conjugate base making the
acid stronger.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.7
Which of the following groups most strongly
activates an aromatic ring toward Friedel–
Crafts acylation?
A.
B.
C.
D.
E.
-NH2
-OCH3
-O-C(=O)CH3
NO2
H
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.7
Which of the following groups most strongly
activates an aromatic ring toward Friedel–
Crafts acylation?
A.
B.
C.
D.
E.
-NH2
-OCH3
-O-C(=O)CH3
NO2
H
Although the -NH2 group is
a stronger activator, it
complexes with AlCl3 to
form a strongly deactivating
ammonium group.
Consequently, the methoxy
is a better activator.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.8
Which step in the following reaction will
cause the proposed synthesis to fail?
A
B
Cl
NBS
Br
light
AlCl3 cat.
C
(H3C)3C
O
E
MnO2
HO
D
1. Hg(OAc)2, H 2O
2. NaBH4
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
O
-
16.8
Which step in the following reaction will
cause the proposed synthesis to fail?
A
B
Cl
NBS
Br
light
AlCl3 cat.
C
(H3C)3C
O
E
MnO2
HO
O
-
D
1. Hg(OAc)2, H 2O
2. NaBH4
Addition of water in step D occurs with Markovnikov selectivity.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.