Deck 17: Reactions of Aromatic Compounds

Question 1

Name the major organic product which results when 3-ethylbenzenesulfonic acid is heated in aqueous acid.

Answer 1

ethylbenzene

Question 2

Which of the following compounds will undergo bromination most rapidly using Br₂, FeBr₃?

A) p-methylacetanilide
B) bromobenzene
C) acetanilide
D) benzenesulfonic acid
E) dibromobenzene

Answer 2

p-methylacetanilide

Question 3

In the bromination of benzene using Br₂ and FeBr₃, is the intermediate carbocation aromatic? Explain.

Answer 3

No, the carbocation is not aromatic since the ring contains an sp³ center.

Question 4

Which of the following compounds will react most rapidly when treated with CH₃CH₂Cl and AlCl₃?

A) benzene
B) chlorobenzene
C) nitrobenzene
D) anisole
E) toluene

Question 5

In electrophilic aromatic substitution reactions, a -NHCOCH₃ substituent on the aromatic ring is ________.

A) a deactivator and a m-director
B) a deactivator and an o,p-director
C) an activator and a m-director
D) an activator and an o,p-director
E) none of the above

Question 6

Electrophilic iodination of benzene requires which reagent in addition to I₂?

Question 7

Provide the structure of the major organic product(s) in the following reaction.

Question 8

Under what reaction conditions does the electrophilic chlorination of aromatic compounds usually occur?

A) Cl₂, AlCl₃
B) Cl₂, H₂O
C) Cl₂, CCl₄
D) NaCl, H₂O
E) NaCl, CH₃OH

Question 9

In electrophilic aromatic substitution reactions a bromine substituent ________.

A) is a deactivator and a m-director
B) is a deactivator and an o,p-director
C) is an activator and a m-director
D) is an activator and an o,p-director
E) none of the above

Question 10

Which of the following is the strongest activating group in electrophilic aromatic substitution reactions?

A) -CH₂CH₃
B) -OCH₃
C) -CO₂CH₃
D) -NO₂
E) -N(CH₃)₂

Question 11

Provide the major resonance structures of the intermediate sigma complex in the reaction of benzene with the generic electrophile E⁺.

Question 12

Which of the following is the best choice of reagents to effect the electrophilic iodination of an aromatic ring?

A) KI, acetone
B) I₂, CH₃CN
C) KI, HNO₃
D) I₂, HNO₃
E) none of the above

Question 13

Which sequence correctly ranks the following aromatic rings in order of increasing rate of reactivity with chlorine and aluminum chloride?

A) 1 < 2 < 3
B) 2 < 3 < 1
C) 3 < 2 < 1
D) 2 < 1 < 3
E) 1 < 3 < 2

Question 14

In electrophilic aromatic substitution reactions the hydroxyl group is an o,p-director because ________.

A) it donates electron density to the ring by induction and destabilizes the meta sigma complex
B) it donates electron density to the ring by resonance and stabilizes the ortho and para sigma complexes
C) it donates electron density to the ring by induction and stabilizes the ortho and para sigma complexes
D) it donates electron density to the ring by resonance and destabilizes the meta sigma complex
E) it withdraws electron density from the ring by induction and destabilizes the meta sigma complex

Question 15

Which step in an electrophilic aromatic substitution reaction is typically rate determining, formation of the sigma complex or loss of H⁺ by the sigma complex to form the product? Explain.

Question 16

The nitration of anisole ________.

A) proceeds more rapidly than the nitration of benzene and yields predominantly the meta product
B) proceeds more rapidly than the nitration of benzene and yields predominantly the ortho, para products
C) proceeds more slowly than the nitration of benzene and yields predominantly the meta product
D) proceeds more slowly than the nitration of benzene and yields predominantly the ortho, para products
E) proceeds at the same rate as the nitration of benzene and yields predominantly the meta product

Question 17

Which of the following is an incorrect statement about the bromination of benzene by Br₂ and FeBr₃?

A) FeBr₃ functions to increase the electrophilicity of Br₂.
B) Formation of the sigma complex is the rate-determining step of the mechanism.
C) The carbanionic intermediate is resonance stabilized.
D) There is one carbon-containing intermediates in the mechanism.
E) The final step of the mechanism is loss of H⁺.

Question 18

Provide a detailed, stepwise mechanism for the reaction of benzene with Br₂ and FeBr₃. Make sure to include the activating reaction between Br₂ and FeBr₃ in your mechanism.

Question 19

Which of the following species is attacked by benzene in the electrophilic nitration reaction?

A) HNO₃
B) NO₂⁺
C) NO₂
D) NO⁺
E) N₃^-

Question 20

Which of the following compounds will undergo Friedel-Crafts alkylation with (CH₃)₃CCl, AlCl₃ most rapidly?

A) toluene
B) iodobenzene
C) acetophenone
D) benzenesulfonic acid
E) cyanobenzene

Question 21

Which of the following compounds will react least rapidly when treated with CH₃CH₂Cl and AlCl₃?

A) o-xylene
B) acetanilide
C) toluene
D) benzene
E) bromobenzene

Question 22

Draw the four major resonance structures of the sigma complex intermediate in the reaction of anisole with HNO₃/H₂SO₄ to yield p-nitroanisole.

Question 23

Provide the major organic product of the following reaction.

Question 24

In electrophilic aromatic substitution reactions the nitro group is ________.

A) a m-director since it destabilizes the meta sigma complex more than the ortho, para
B) a m-director since it destabilizes the meta sigma complex less than the ortho, para
C) an o,p-director since it stabilizes the ortho, para sigma complex more than the meta
D) an o,p-director since it stabilizes the ortho, para sigma complex less than the meta
E) none of the above

Question 25

In electrophilic aromatic substitution reactions, a phenyl substituent on the aromatic ring is ________.

A) a deactivator and a m-director
B) a deactivator and an o,p-director
C) an activator and a m-director
D) an activator and an o,p-director
E) none of the above

Question 26

Draw a mechanism for the following reaction.

Question 27

In electrophilic aromatic substitution reactions, a -CO₂H substituent on the aromatic ring is ________.

A) a deactivator and a m-director
B) a deactivator and an o,p-director
C) an activator and a m-director
D) an activator and an o,p-director
E) none of the above

Question 28

Provide the major organic product of the following reaction.

Question 29

In electrophilic aromatic substitution reactions, a cyano substituent on the aromatic ring is ________.

A) a deactivator and a m-director
B) a deactivator and an o,p-director
C) an activator and a m-director
D) an activator and an o,p-director
E) none of the above

Question 30

Which of the following compounds will not undergo Friedel-Crafts acylation when treated with

A) toluene
B) p-xylene
C) anisole
D) ethoxybenzene
E) benzophenone

Question 31

In the addition of an electrophile to acetophenone, which of the following best describes the expected mode of reaction?

A) The o,p-positions are most activated to attack by the electrophile.
B) The m-positions are most activated to attack by the electrophile.
C) The o,p-positions are most deactivated to attack by the electrophile.
D) The m-positions are most deactivated to attack by the electrophile.
E) All positions (o, m, and p) are equally activated to attack by the electrophile.

Question 32

Which sequence correctly ranks the following aromatic rings in order of increasing rate of reactivity in an electrophilic aromatic substitution reaction?

A) 1 < 2 < 3
B) 2 < 3 < 1
C) 3 < 1 < 2
D) 2 < 1 < 3

Question 33

Provide the structure of the major organic product(s) in the following reaction.

Question 34

Provide the structure of the major organic product(s) in the following reaction.

Question 35

Rank the following compounds in order of increasing reactivity towards chlorination with Cl₂/AlCl₃ (slowest reacting to fastest).

A) 3 < 4 < 2 < 1 < 5
B) 2 < 4 < 1 < 3 < 5
C) 4 < 2 < 1 < 3 < 5
D) 2 < 4 < 5 < 1 < 3
E) 2 < 4 < 1 < 5 < 3

Question 36

Derivatives of the compound shown below are currently being examined for their effectiveness in treating drug addiction and metabolic syndrome (J. Med. Chem. 2006, 872). Which sequence ranks the following aromatic rings of this compound in order of increasing reactivity in an electrophilic aromatic substitution reaction (slowest to fastest reacting)?

A) 1 < 2 < 3
B) 2 < 3 < 1
C) 3 < 2 < 1
D) 3 < 1 < 2
E) 2 < 1 < 3

Question 37

Draw the three major resonance structures of the sigma complex intermediate in the reaction of acetophenone with HNO₃/H₂SO₄ to yield o-nitroacetophenone. Circle the resonance form which is less stable than the other two.

Question 38

Which of the following compounds will undergo bromination least rapidly when treated with Br₂ and FeBr₃?

A) p-methylacetanilide
B) bromobenzene
C) acetanilide
D) benzenesulfonic acid
E) benzene

Question 39

Which of the following is an intermediate in the bromination of toluene?

A)
B)
C)
D)

Question 40

Provide the structure of the major mononitration product of the compound below.

Question 41

Provide the major organic product(s) of the reaction shown below.

Question 42

Provide the major organic product(s) when benzene is treated with the following sequence of reagents: 1. Br₂, FeBr₃ 2. CH₃COCl, AlCl₃.

Question 43

Provide the major organic product of the following reaction.

Question 44

Provide the major organic product(s) of the reaction shown below.

Question 45

Provide the major organic product(s) of the reaction shown below.

Question 46

Provide the major organic product of the following reaction.

Question 47

Use resonance structures to explain why the substituent shown below is an activating group.

Question 48

Provide the major organic product that results when benzene is treated with the following sequence of reagents: 1. HNO₃, H₂SO₄ 2. Br₂, FeBr₃.

Question 49

Which of the following compounds undergoes reaction with HNO₃/H₂SO₄ at the fastest rate?

A) ethylbenzene
B) benzenesulfonic acid
C) nitrobenzene
D) chlorobenzene
E) acetophenone

Question 50

Explain why -OCH₃ is a stronger activator than -OCOCH₃.

Question 51

Provide the major organic product of the following reaction.

Question 52

Provide the major organic product(s) when benzene is treated with the following sequence of reagents: 1. Br₂, FeBr₃ 2. HNO₃, H₂SO₄.

Question 53

Provide the major organic product of the following reaction.

Question 54

Provide the major organic product of the following reaction.

Question 55

Provide the structure of the major mononitration product(s) of the compound below.

Question 56

Provide the major organic product(s) of the reaction shown below.

Question 57

Provide the major organic product of the following reaction.

Question 58

Provide the major organic product that results when benzene is treated with the following sequence of reagents: 1. CH₃COCl, AlCl₃ 2. Br₂, FeBr₃.

Question 59

Provide the major organic product(s) of the reaction shown below.

Question 60

Rank the following groups in order of increasing activating power in electrophilic aromatic substitution reactions:


-Br.

Question 61

Provide the major organic product of the following reaction.

Question 62

Provide the major organic product of the following reaction.

Question 63

Provide the major organic product of the following reaction.

Question 64

Provide the structure of the major mononitration product of the compound below.

Question 65

Provide the major organic product of the following reaction.

Question 66

Provide the major organic product of the following reaction.

Question 67

In electrophilic aromatic substitution reactions, the -CF₃ group is ________.

A) an activating group because it donates electron density through inductive stabilization
B) an activating group because it donates electron density through resonance
C) a deactivating group because it withdraws electron density through inductive destabilization
D) a deactivating group because it withdraws electron density through resonance

Question 68

List two of the three limitations usually associated with the Friedel-Crafts alkylation reaction.

Question 69

What sequence of reagents is needed to convert benzene into m-bromoethylbenzene?

Question 70

Provide the structure of the major organic product of the following reaction.

Question 71

Predict the products from the following reaction.

Question 72

Provide the major organic product of the following reaction.

Question 73

Provide the structure of the major mononitration product(s) of the compound below.

Question 74

Provide the structure of the major monoitration product of the compound below.

Question 75

Provide the structure of the major mononitration product of the compound below.

Question 76

Provide a detailed, stepwise mechanism for the following reactions.

Question 77

Provide the major organic product(s) of the reaction shown below.

Question 78

Provide a series of synthetic steps by which the compound below can be prepared from benzene.

Question 79

Draw a mechanism for the reaction shown below.

Question 80

Which of the following reactions will actually yield the indicated product?

A)
B)
C)
D)
E)