Deck 17: Reactions of Aromatic Compounds

Question 1

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

Answer 1

I₂, HNO₃

Question 2

Provide the necessary reagents to accomplish the following transformation.

Answer 2

1) SO₃ / H₂SO₄
2) excess Br₂ / FeBr₃
3) H⁺, H₂O, heat

Question 3

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

Answer 3

-N(CH₃)₂

Question 4

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 5

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 6

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 7

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

Question 8

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 9

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

Question 10

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 11

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

Question 12

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 are two carbon-containing intermediates in the mechanism.
E) The final step of the mechanism is loss of H⁺.

Question 13

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 14

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

Question 15

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 16

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 17

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 18

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 19

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

Question 20

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

Question 21

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

Question 22

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 23

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 24

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 25

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 26

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

Question 27

Provide the major organic product of the following reaction.

Question 28

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

A)

B)

C)

D)

Question 29

Based upon the following energy profile diagram for the first step of an electrophilic aromatic substitution reaction, which of the following substituents is X mostly likely to be?

A) Cl
B) OCH₃
C) CO₂H
D) CH₃

Question 30

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 31

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 32

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 33

Provide the major organic product of the following reaction.

Question 34

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 35

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 36

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 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

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

Question 39

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 40

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 41

Provide the major organic product of the following reaction.

Question 42

Provide the major organic product of the following reaction.

Question 43

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

Question 44

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

Question 45

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 46

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

Question 47

Rank the following sigma complexes in order of increasing stability.

Question 48

Provide the major organic product of the following reaction.

Question 49

Rank the following groups in order of increasing activating power in electrophilic aromatic substitution reactions: -OCH₃, -OCOCH₂CH₃, -CH₂CH₃, -Br.

Question 50

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

Question 51

Provide the major organic product of the following reaction.

Question 52

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

Question 53

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

Question 54

Provide the major organic product of the following reaction.

Question 55

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

Question 56

Provide the major organic product of the following reaction.

Question 57

Provide the structure of the most stable resonance form of the intermediate that yields p-bromoanisole when anisole is treated with Br₂/FeBr₃.

Question 58

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

Question 59

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

Question 60

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

Question 61

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

Question 62

Provide the major organic product of the following reaction.

Question 63

Provide the major organic product of the following reaction.

Question 64

Predict the two major products from the following reaction. (Mark all correct responses.)

A)

B)

C)

D)

E)

Question 65

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

Question 66

List $\underline{\text{ two }}$ of the three limitations usually associated with the Friedel-Crafts alkylation reaction.

Question 67

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

Question 68

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

Question 69

Provide the major organic product of the following reaction.

Question 70

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

Question 71

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

Question 72

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

A)

B)

C)

D)

E)

Question 73

Provide the major organic product of the following reaction.

Question 74

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

Question 75

Provide a detailed, stepwise mechanism for the following reactions.

Question 76

Provide the major organic product of the following reaction.

Question 77

Provide the major organic product of the following reaction.

Question 78

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

Question 79

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

Question 80

Provide the major organic product of the following reaction.