1. 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.

2. Which combination of reagents is best suited to prepare benzaldehyde?
16.1
Which combination of reagents is best suited to prepare benzaldehyde?
Toluene, 1. CrO3, H2SO LiAlH H2O
Toluene, 1. CrO3, H2SO NaBH4 3. H2O
Toluene, 1. MnO LiAlH4 3. PCC
Toluene, 1. CrO3, H2SO LiAlH4 3. PCC
Toluene, PCC
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

3. Which combination of reagents is best suited to prepare benzaldehyde?
16.1
Which combination of reagents is best suited to prepare benzaldehyde?
Toluene, 1. CrO3, H2SO LiAlH H2O
Toluene, 1. CrO3, H2SO NaBH4 3. H2O
Toluene, 1. MnO LiAlH4 3. PCC
Toluene, 1. CrO3, H2SO LiAlH4 3. PCC
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.

4. Which of the following groups is an activator?
16.3
Which of the following groups is an activator?
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

5. Which of the following groups is an activator?
16.3
Which of the following groups is an activator?
Generally, except for the halogens, groups with lone pairs of electrons adjacent to the ring are activators.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

6. Which of the following groups is an ortho–para director?
16.4
Which of the following groups is an ortho–para director?
-Cl
-CHO
-CN
-NO2
None of the above
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

7. Which of the following groups is an ortho–para director?
16.4
Which of the following groups is an ortho–para director?
-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- p- director.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

8. Which compound is the major product of the chlorination shown below?
16.4
Which compound is the major product of the chlorination shown below?
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

9. Which compound is the major product of the chlorination shown below?
16.4
Which compound is the major product of the chlorination shown below?
The nitrogen is an activator and o- p- director. The C=O is a deactivator.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

10. Which benzoic acid derivative has the lowest pKa?
16.5
Which benzoic acid derivative has the lowest pKa?
R =
-Br
-CF3 -H
-OCH3
-OH
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

11. Which benzoic acid derivative has the lowest pKa?
16.5
Which benzoic acid derivative has the lowest pKa?
R =
-Br pKa = 4.00
-CF3 pKa = 3.67
-H pKa = 4.20
-OCH3 pKa = 4.47
-OH pKa = 4.48
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.

12. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.7
Which of the following groups most strongly activates an aromatic ring toward Friedel–Crafts acylation?
-NH2
-OCH3
-O-C(=O)CH3
NO2 H
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

13. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.7
Which of the following groups most strongly activates an aromatic ring toward Friedel–Crafts acylation?
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.
-NH2
-OCH3
-O-C(=O)CH3
NO2 H
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

14. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.8
Which step in the following reaction will cause the proposed synthesis to fail?
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.

15. Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
16.8
Which step in the following reaction will cause the proposed synthesis to fail?
Addition of water in step D occurs with Markovnikov selectivity.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.