1. 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.

2. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.1
The difference in energy between “cyclohexatriene” and benzene is __kcal/mol.
+49.8
+28.8
-28.8
-36.0
-85.8
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

3. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.1
The difference in energy between “cyclohexatriene” and benzene is __kcal/mol.
+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.

4. Assuming planarity, which of the following molecules is aromatic?
15.3
Assuming planarity, which of the following molecules is aromatic?
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

5. Assuming planarity, which of the following molecules is aromatic?
15.3
Assuming planarity, which of the following molecules is aromatic?
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.

6. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.7
Which of the following molecular orbital diagrams best fits that of pyrrole?
pyrrole A B C D
E None of the above
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

7. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.7
Which of the following molecular orbital diagrams best fits that of pyrrole?
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.

8. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.10
Which of the following statements regarding electrophilic aromatic substitution is incorrect?
Halogenation: Br, Cl, or I substitutes for a hydrogen.
Nitration: -NH2 substitutes for a hydrogen.
Sulfonation: -SO3H substitutes for a hydrogen.
Friedel–Crafts acylation: RC=O (acyl) substitutes for a hydrogen.
Friedel–Crafts alkylation: R (alkyl) substitutes for a hydrogen.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

9. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.10
Which of the following statements regarding electrophilic aromatic substitution is incorrect?
Halogenation: Br, Cl, or I substitutes for a hydrogen.
Nitration: -NH2 substitutes for a hydrogen.
Sulfonation: -SO3H substitutes for a hydrogen.
Friedel–Crafts acylation: RC=O (acyl) substitutes for a hydrogen.
Friedel–Crafts alkylation: R (alkyl) substitutes for a hydrogen.
Nitration involves –NO2 substitution.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

10. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
Which combination of reagents is best suited to prepare n-propylbenzene?
Benzene, CH3CH2CH2Cl, AlCl3 catalyst
Benzene, CH3CH=CH2, HF catalyst
Benzene, 1. CH3CH2COCl, AlCl3 cat. 2. Zn(Hg) HCl
Benzene, CH3CH2CH2OH, H2SO4
Chlorobenzene, CH3CH=CH2, AlCl3 catalyst
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

11. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
Which combination of reagents is best suited to prepare n-propylbenzene?
Benzene, CH3CH2CH2Cl, AlCl3 catalyst
Benzene, CH3CH=CH2, HF catalyst
Benzene, 1. CH3CH2COCl, AlCl3 cat. 2. Zn(Hg) HCl
Benzene, CH3CH2CH2OH, H2SO4
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.

12. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.17
Which combination of reagents is acceptable for the preparation of n-propylbenzene?
Bromobenzene, (CH3CH2CH2)2CuLi (Gillman)
Bromobenzene, (CH3CH2CH2)4Sn, PdL2 cat. (Stille)
Bromobenzene, RO2B(CH2)2CH3, PdL2, HO- (Suzuki)
Propyl bromide, (C6H5)2CuLi (Gillman)
Any of the above
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

13. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
15.17
Which combination of reagents is acceptable for the preparation of n-propylbenzene?
Bromobenzene, (CH3CH2CH2)2CuLi (Gillman)
Bromobenzene, (CH3CH2CH2)4Sn, PdL2 cat. (Stille)
Bromobenzene, RO2B(CH2)2CH3, PdL2, HO- (Suzuki)
Propyl bromide, (C6H5)2CuLi (Gillman)
Any of the above
Organometallic mediated coupling reactions are very versatile.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.