Organic Chemistry, 6th edition
Paula Yurkanis Bruice
Chapter 15
Aromaticity
Reactions of Benzene
Brian L. Groh
Minnesota State University, Mankato
Mankato, MN
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.1
The difference in energy between
“cyclohexatriene” and benzene is __kcal/mol.
A.
B.
C.
D.
E.
+49.8
+28.8
-28.8
-36.0
-85.8
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.1
The difference in energy between
“cyclohexatriene” and benzene is __kcal/mol.
A.
B.
C.
D.
E.
+49.8
+28.8
-28.8
-36.0
-85.8
Benzene is 36.0 kcal/mol more
stable than the theoretical
cyclohexatriene.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.3
Assuming planarity, which of the following
molecules is aromatic?
N
A
B
C
D
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
E
15.3
Assuming planarity, which of the following
molecules is aromatic?
N
A
B
C
D
E
This is a 4n + 2 pi electron system. The lone pair of
electrons on the nitrogen atom are perpendicular to the pi
electrons and cannot interact with them.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.7
Which of the following molecular
orbital diagrams best fits that of
pyrrole?
A
B
C
D
E None of the above
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
N
pyrrole
H
15.7
Which of the following molecular
orbital diagrams best fits that of
pyrrole?
N
H
pyrrole
A
B
C
The lone pair of electrons on
the nitrogen atom are
included with the pi electrons
to give a 4n+2 pi electron
system.
E None of the above
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.10 Which of the following statements regarding
electrophilic aromatic substitution is incorrect?
A. Halogenation: Br, Cl, or I substitutes for a hydrogen.
B. Nitration: -NH2 substitutes for a hydrogen.
C. Sulfonation: -SO3H substitutes for a hydrogen.
D. Friedel–Crafts acylation: RC=O (acyl) substitutes for
a hydrogen.
E. Friedel–Crafts alkylation: R (alkyl) substitutes for a
hydrogen.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.10 Which of the following statements regarding
electrophilic aromatic substitution is incorrect?
A. Halogenation: Br, Cl, or I substitutes for a hydrogen.
B. Nitration: -NH2 substitutes for a hydrogen.
C. Sulfonation: -SO3H substitutes for a hydrogen.
D. Friedel–Crafts acylation: RC=O (acyl) substitutes for
a hydrogen.
E. Friedel–Crafts alkylation: R (alkyl) substitutes for a
hydrogen.
Nitration involves –NO2 substitution.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.14- Which combination of reagents is
15.16 best suited to prepare
n-propylbenzene?
A. Benzene, CH3CH2CH2Cl, AlCl3 catalyst
B. Benzene, CH3CH=CH2, HF catalyst
C. Benzene, 1. CH3CH2COCl, AlCl3 cat. 2. Zn(Hg) HCl
D. Benzene, CH3CH2CH2OH, H2SO4
E. Chlorobenzene, CH3CH=CH2, AlCl3 catalyst
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.14- Which combination of reagents is
15.16 best suited to prepare
n-propylbenzene?
A. Benzene, CH3CH2CH2Cl, AlCl3 catalyst
B. Benzene, CH3CH=CH2, HF catalyst
C. Benzene, 1. CH3CH2COCl, AlCl3 cat. 2. Zn(Hg) HCl
D. Benzene, CH3CH2CH2OH, H2SO4
E. Chlorobenzene, CH3CH=CH2, AlCl3 catalyst
Attempted direct alkylation (“A”) using a primary halide will
result in rearrangement of the carbocation intermediate.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.17 Which combination of reagents is
acceptable for the preparation of
n-propylbenzene?
A. Bromobenzene, (CH3CH2CH2)2CuLi (Gillman)
B. Bromobenzene, (CH3CH2CH2)4Sn, PdL2 cat. (Stille)
C. Bromobenzene, RO2B(CH2)2CH3, PdL2, HO- (Suzuki)
D. Propyl bromide, (C6H5)2CuLi (Gillman)
E. Any of the above
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.17 Which combination of reagents is
acceptable for the preparation of
n-propylbenzene?
A. Bromobenzene, (CH3CH2CH2)2CuLi (Gillman)
B. Bromobenzene, (CH3CH2CH2)4Sn, PdL2 cat. (Stille)
C. Bromobenzene, RO2B(CH2)2CH3, PdL2, HO- (Suzuki)
D. Propyl bromide, (C6H5)2CuLi (Gillman)
E. Any of the above
Organometallic mediated coupling
reactions are very versatile.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.