Deck 14: Aromatic Compounds

Question 1

Which of the following is NOT 2-bromo-5-nitrobenzoic acid?

A) I
B) II
C) III
D) IV
E) V

Answer 1

IV

Question 2

Which reagent(s)would serve as the basis for a simple chemical test that would distinguish between naphthalene and 2,4,6-decatriene?

A) NaOH in H₂O
B) KMnO₄,OH ^- ,H₂O
C) NaBH₄,H₂O
D) H₂CrO₄
E) None of these

Answer 2

KMnO₄,OH ^- ,H₂O

Question 3

Which reagent(s)would serve as the basis for a simple chemical test that would distinguish between benzene and cyclohexene?

A) NaOH in H₂O
B) Br₂ in CCl₄
C) AgNO₃ in C₂H₅OH
D) NaHSO₃ in H₂O
E) None of these

Answer 3

Br₂ in CCl₄

Question 4

Phenol is the name commonly assigned to:

A) Hydroxybenzene
B) Aminobenzene
C) Methylbenzene
D) Ethylbenzene
E) Methoxybenzene

Question 5

Which dibromobenzene can,in theory,yield three mononitro derivatives?

A) o-Dibromobenzene
B) m-Dibromobenzene
C) p-Dibromobenzene
D) All of these
E) None of these

Question 6

In theory,a single molecule of this compound will rotate plane-polarized light.

A) Butylbenzene
B) Isobutylbenzene
C) sec-Butylbenzene
D) tert-Butylbenzene
E) None of these

Question 7

Xylene is the name commonly assigned to:

A) Hydroxybenzene
B) Aminobenzene
C) Dimethylbenzene
D) Ethylbenzene
E) Methoxybenzene

Question 8

Toluene is the name commonly assigned to:

A) Hydroxybenzene
B) Aminobenzene
C) Methylbenzene
D) Ethylbenzene
E) Methoxybenzene

Question 9

Which dibromobenzene can yield only one mononitro derivative?

A) o-Dibromobenzene
B) m-Dibromobenzene
C) p-Dibromobenzene
D) More than one of these
E) None of these

Question 10

Which dihydroxybenzene can yield only one mononitro derivative?

A) o-Dihydroxybenzene
B) m-Dihydroxybenzene
C) p- Dihydroxybenzene
D) More than one of these
E) None of these

Question 11

Which reagent(s)would serve as the basis for a simple chemical test that would distinguish between ethylbenzene and vinylcyclohexane?

A) H₂CrO₄
B) LAH
C) NaBH₄,H₂O
D) O₃/Zn,H⁺
E) Two of the above

Question 12

If thiophene is an aromatic molecule and reacts similarly to benzene,how many (neutral)monobromothiophenes could be obtained in the following reaction?

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

Question 13

How many different dibromophenols are possible?

A) 8
B) 7
C) 6
D) 5
E) 4

Question 14

Aniline is the name commonly assigned to:

A) Hydroxybenzene
B) Aminobenzene
C) Methylbenzene
D) Ethylbenzene
E) Methoxybenzene

Question 15

Which reagent(s)would serve as the basis for a simple chemical test that would distinguish between ethylbenzene and vinylcyclohexane?

A) H₂CrO₄
B) LAH
C) NaBH₄,H₂O
D) KMnO₄,OH ^- ,H₂O
E) Two of the above

Question 16

Which reagent(s)would serve as the basis for a simple chemical test that would distinguish between benzene and 1-hexene?

A) NaOH in H₂O
B) Br₂ in CCl₄
C) AgNO₃ in C₂H₅OH
D) NaHSO₃ in H₂O
E) None of these

Question 17

Anisole is the name commonly assigned to:

A) Hydroxybenzene
B) Aminobenzene
C) Methylbenzene
D) Ethylbenzene
E) Methoxybenzene

Question 18

The correct name for the compound shown below is:

A) 3,4-Dibromoaniline
B) 2,4-Dibromoaniline
C) 2,5-Dibromoaniline
D) 3,6-Dibromoaniline
E) 2,6-Dibromoaniline

Question 19

Which is the only one of these reagents which will react with benzene under the specified conditions?

A) Cl₂,FeCl₃,heat
B) H₂,25°C
C) Br₂/CCl₄,25°C,dark
D) KMnO₄/H₂O,25°C
E) H₃O⁺,heat

Question 20

Which dichlorobenzene might theoretically yield three mononitro products?

A) o-Dichlorobenzene
B) m-Dichlorobenzene
C) p-Dichlorobenzene
D) None of these
E) All of these

Question 21

In which of the following compounds would the longest carbon-carbon bond(s)be found?

A) 2-Bromobenzaldehyde
B) Vinylbenzene
C) 1,3,5-Heptatriene
D) 2,4,6-Octatriene
E) 2-Ethylbenzoic acid

Question 22

Of Hückel's requirements for aromatic character,only this one is waived in the case of certain compounds considered to be aromatic.

A) The ring system must be planar.
B) The system must be monocyclic.
C) There must be (4n + 2) $\pi$ electrons.
D) The Hückel number of electrons must be completely delocalized.
E) None.All of these rules must apply in every case.

Question 23

Which of the following statements regarding the cyclopropenyl anion is correct?

A) It is aromatic.
B) It is not aromatic.
C) It obeys Hückel's rule.
D) It undergoes reactions characteristic of benzene.
E) It has a closed shell of 6 pi-electrons.

Question 24

How many different dichloronitrobenzenes are possible?

A) 8
B) 7
C) 6
D) 5
E) 4

Question 25

Which of the following is true of benzene?

A) Benzene tends to undergo addition rather than substitution reactions.
B) All of the hydrogen atoms of benzene are equivalent.
C) The carbon-carbon bonds of benzene are alternately short and long around the ring.
D) The benzene ring is a distorted hexagon.
E) Benzene has the stability expected for cyclohexatriene.

Question 26

In which of the following compounds would the shortest carbon-carbon bond(s)be found?

A) Toluene
B) 2-Ethylcyclopentene
C) 4-Methyl-1,3-cyclohexadiene
D) 3-Methyl-1-hexyne
E) 3-Methyl-1,3-hexadiene

Question 27

Why would 1,3-cyclohexadiene undergo dehydrogenation readily?

A) It is easily reduced.
B) Hydrogen is a small molecule.
C) 1,3-Cyclohexadiene has no resonance energy.
D) It would gain considerable stability by becoming benzene.
E) It would not undergo dehydrogenation.

Question 28

Which of the following statements regarding the cycloheptatrienyl anion is correct?

A) It is aromatic.
B) It is not aromatic.
C) It obeys Hückel's rule.
D) It undergoes reactions characteristic of benzene.
E) It has a closed shell of 6 pi-electrons.

Question 29

In the molecular orbital model of benzene,how many pi-electrons are delocalized about the ring?

A) 2
B) 3
C) 4
D) 5
E) 6

Question 30

Which of the following is NOT true of benzene?

A) Benzene tends to undergo substitution rather than addition reactions,even though it has a high index of hydrogen deficiency.
B) All of the hydrogen atoms of benzene are equivalent.
C) The carbon-carbon bonds of benzene are alternately short and long around the ring.
D) Only one o-dichlorobenzene has ever been found.
E) Benzene is more stable than the hypothetical compound 1,3,5-cyclohexatriene.

Question 31

In the molecular orbital model of benzene,how many pi-electrons are in bonding molecular orbitals?

A) 6
B) 5
C) 4
D) 3
E) 2

Question 32

We now know that the two Kekule structures for benzene are related in the following way:

A) They are each equally correct as a structure for benzene.
B) Benzene is sometimes one structure and sometimes the other.
C) The two structures are in a state of rapid equilibrium.
D) Neither of the two structures adequately describes benzene;benzene is a resonance hybrid of the two.
E) None of the above

Question 33

Which of the following statements regarding the cyclopentadienyl radical is correct?

A) It is aromatic.
B) It is not aromatic.
C) It obeys Huckel's rule.
D) It undergoes reactions characteristic of benzene.
E) It has a closed shell of 6 pi-electrons.

Question 34

The carbon-carbon bonds in benzene are:

A) of equal length and are shorter than the double bond of ethene.
B) of equal length and are intermediate between a double bond and a single bond.
C) of unequal length and are alternately short and long around the ring.
D) due only to p-orbital overlap.
E) of equal length and intermediate between the carbon-carbon bond lengths in ethene and ethyne.

Question 35

Which of the following statements regarding the cycloheptatrienyl radical is correct?

A) It is aromatic.
B) It is not aromatic.
C) It obeys Hückel's rule.
D) It undergoes reactions characteristic of benzene.
E) It has a closed shell of 6 pi-electrons.

Question 36

Recalling that benzene has a resonance energy of 152 kJ mol^-1 and naphthalene has a resonance energy of 255 kJ mol^-1,predict the positions which would be occupied by bromine when phenanthrene (below)undergoes addition of Br₂.

A) 1,2
B) 1,4
C) 3,4
D) 7,8
E) 9,10

Question 37

Which of the following statements regarding the cyclopropenyl radical is correct?

A) It is aromatic.
B) It is not aromatic.
C) It obeys Hückel's rule.
D) It undergoes reactions characteristic of benzene.
E) It has a closed shell of 6 pi-electrons.

Question 38

How many different dihydroxybromobenzenes are possible?

A) 8
B) 7
C) 6
D) 5
E) 4

Question 39

Consider the molecular orbital model of benzene.In the ground state how many molecular orbitals are filled with electrons?

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

Question 40

Which of the following statements regarding the cyclopentadienyl cation is correct?

A) It is aromatic.
B) It is not aromatic.
C) It obeys Hückel's rule.
D) It undergoes reactions characteristic of benzene.
E) It has a closed shell of 6 pi-electrons.

Question 41

Which of the following would you expect to be aromatic?

A) I
B) II
C) III
D) IV
E) All of these

Question 42

On the basis of molecular orbital theory and Hückel's rule,which molecules and/or ions should be non-aromatic?

A) I and V
B) I and II
C) III and VIII
D) IV,VII and IX
E) IV,VI,VII and IX

Question 43

In the molecular orbital model of benzene,how many $\pi$ -bonding molecular orbitals are there?

A) 6
B) 5
C) 4
D) 3
E) 2

Question 44

In the molecular orbital model of benzene,the six p-orbitals combine to form how many molecular orbitals?

A) 6
B) 5
C) 4
D) 3
E) 2

Question 45

On the basis of molecular orbital theory and Hückel's rule,which of these compounds should be aromatic?

A) I
B) II
C) III
D) IV
E) V

Question 46

How many equivalent resonance structures can be written for the cycloheptatrienyl cation?

A) 3
B) 4
C) 5
D) 6
E) 7

Question 47

On the basis of molecular orbital theory and Hückel's rule,which molecules and/or ions should be aromatic?

A) I and V
B) III and VIII
C) IV,VII and IX
D) IV,VI,VII and IX
E) All of the structures,I-IX

Question 48

Which of the following would you expect to be aromatic?

A) I
B) II
C) III
D) IV
E) V

Question 49

How many equivalent resonance structures can be written for the cyclopentadienyl anion?

A) 3
B) 4
C) 5
D) 6
E) 7

Question 50

Which of these is an aromatic molecule?

A) I
B) II
C) III
D) IV
E) V

Question 51

Cyclopentadiene is unusually acidic for a hydrocarbon.An explanation for this is the following statement.

A) The carbon atoms of cyclopentadiene are all sp²-hybridized.
B) Cyclopentadiene is aromatic.
C) Removal of a proton from cyclopentadiene yields an aromatic anion.
D) Removal of a hydrogen atom from cyclopentadiene yields a highly stable free radical.
E) Removal of a hydride ion from cyclopentadiene produces an aromatic cation.

Question 52

Which of the following would you expect to be aromatic?

A) I
B) II
C) III
D) IV
E) None of the above

Question 53

On the basis of molecular orbital theory and Hückel's rule,which of these compounds should be aromatic?

A) I
B) II
C) III
D) IV
E) V

Question 54

On the basis of molecular orbital theory and Hückel's rule,which molecules and/or ions should be antiaromatic?

A) I and V
B) I and II
C) III and VIII
D) IV,VII and IX
E) IV,VI,VII and IX

Question 55

Which of the following would you expect to be aromatic?

A) I
B) II
C) III
D) IV
E) V

Question 56

Which of the following would you expect to be aromatic?

A) I
B) II
C) III
D) IV
E) None of these

Question 57

Application of the polygon-and-circle technique reveals that single electrons occupy each of the two nonbonding orbitals in the molecular orbital diagram of:

A) Cyclobutadiene
B) Benzene
C) Cyclopropenyl cation
D) Cyclopentadienyl anion
E) Cycloheptatrienyl cation

Question 58

Which of the following structures would be aromatic?

A) I
B) II
C) III
D) IV
E) V

Question 59

Which of these is an aromatic molecule?

A) I
B) II
C) III
D) IV
E) V

Question 60

Which of the following statements about cyclooctatetraene is NOT true?

A) The compound rapidly decolorizes Br₂/CCl₄ solutions.
B) The compound rapidly decolorizes aqueous solutions of KMnO₄.
C) The compound readily adds hydrogen.
D) The compound is nonplanar.
E) The compound is comparable to benzene in stability.

Question 61

In the molecular orbital model of the cyclopentadienyl cation,how many non-bonding molecular orbitals are there?

A) 1
B) 2
C) 3
D) 4
E) 0

Question 62

In the molecular orbital model of cyclobutadiene,how many pairs of degenerate $\pi$ -antibonding molecular orbitals are there?

A) 1
B) 2
C) 3
D) 4
E) 0

Question 63

In the molecular orbital model of benzene,how many $\pi$ -antibonding molecular orbitals are there?

A) 6
B) 5
C) 4
D) 3
E) 2

Question 64

In the molecular orbital model of cyclobutadiene,how many $\pi$ -bonding molecular orbitals are there?

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

Question 65

In the molecular orbital model of cyclobutadiene,how many non-bonding molecular orbitals are there?

A) 1
B) 2
C) 3
D) 4
E) 0

Question 66

In the molecular orbital model of the cyclopentadienyl cation,how many pairs of degenerate $\pi$ -antibonding molecular orbitals are there?

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

Question 67

In the molecular orbital model of benzene,how many pairs of degenerate $\pi$ -bonding molecular orbitals are there?

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

Question 68

In the molecular orbital model of the cyclopentadienyl cation,how many pairs of degenerate $\pi$ -molecular orbitals are there?

A) 6
B) 5
C) 4
D) 3
E) 2

Question 69

Consider the molecular orbital model of cyclopentadienyl anion.In the ground state how many molecular orbitals are filled with electrons?

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

Question 70

In the molecular orbital model of cyclobutadiene,how many $\pi$ -antibonding molecular orbitals are there?

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

Question 71

Which of the following would you expect to be antiaromatic?

A) I
B) II
C) III
D) IV
E) V

Question 72

In the molecular orbital model of cyclobutadiene,how many pairs of degenerate $\pi$ -molecular orbitals are there?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 73

In the molecular orbital model of benzene,how many pairs of degenerate $\pi$ -antibonding molecular orbitals are there?

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

Question 74

In the molecular orbital model of the cyclopentadienyl cation,how many pairs of degenerate $\pi$ -bonding molecular orbitals are there?

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

Question 75

In the molecular orbital model of the cyclopentadienyl cation,how many $\pi$ -bonding molecular orbitals are there?

A) 6
B) 5
C) 4
D) 3
E) 2

Question 76

In the molecular orbital model of benzene,how many pairs of degenerate $\pi$ -molecular orbitals are there?

A) 6
B) 5
C) 4
D) 3
E) 2

Question 77

In the molecular orbital model of the cyclobutadiene,how many pairs of degenerate $\pi$ -bonding molecular orbitals are there?

A) 1
B) 2
C) 3
D) 4
E) 0

Question 78

In the molecular orbital model of the cyclopentadienyl cation,how many $\pi$ -antibonding molecular orbitals are there?

A) 6
B) 5
C) 4
D) 3
E) 2

Question 79

In the molecular orbital model of benzene,how many non-bonding molecular orbitals are there?

A) 1
B) 2
C) 3
D) 4
E) 0

Question 80

Of the following C-10 compounds,which is expected to possess the greatest resonance (delocalization)energy?

A) I
B) II
C) III
D) IV
E) V