Deck 21: Benzene and the Concept of Aromaticity

Question 1

Which orbital contains the lone pair on the nitrogen atom of pyridine?

A) s
B) p
C) sp
D) sp²

Answer 1

sp²

Question 2

Which orbital contains the lone pair on the nitrogen atom of pyrrole?

A) s
B) p
C) sp
D) sp²

Answer 2

p

Question 3

What is the hybridization of the oxygen atom of furan?

A) s
B) sp
C) sp²
D) sp³

Answer 3

sp²

Question 4

What is the correct assignment of the names of the following heterocycles?

A) 1 = pyrrole; 2 = thiophene; 3 = pyridine
B) 1 = thiophene; 2 = furan; 3 = pyrrole
C) 1 = pyridine; 2 = thiophene; 3 = furan
D) 1 = pyridine; 2 = thiophene; 3 = pyrrole

Question 5

What is the correct assignment of the names of the following fused arenes?

A) 1 = naphthalene; 2 = anthracene; 3 = pyrene
B) 1 = naphthalene; 2 = phenanthrene; 3 = coronene
C) 1 = naphthalene; 2 = anthracene; 3 = benzo[a]pyrene
D) 1 = anthracene; 2 = naphthalene; 3 = coronene

Question 6

Which of the following statements is not true about the structure of benzene?

A) six atomic 2p-orbitals overlap to form six π-molecular orbitals
B) there are three bonding π-molecular orbitals and three π-antibonding molecular orbitals
C) the ground state electronic configuration of benzene has six electrons in three π-bonding molecular orbitals
D) the bonds alternate in length around the ring

Question 7

Which of the following is not one of Hückel's criteria for aromaticity?

A) The compound must be cyclic
B) The compound must have one p-orbital on each atom of a ring
C) The compound must be planar or nearly planar so that there is a continuous overlap of p orbitals
D) The compound must have a closed loop of six pi electrons

Question 8

Which orbitals contain the lone pairs on the nitrogen atoms labeled i and ii in the imidazole ring?

A) i = sp^2;; ii = sp³
B) i = p^;; ii = sp³
C) i = p^;; ii = sp³.
D) i = p^;; ii = sp²

Question 9

Which of the following represents the energy levels of the molecular orbitals of benzene?

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

Question 10

What is the approximate length of the carbon-carbon bonds in benzene?

A) 110 pm
B) 121 pm
C) 139 pm
D) 156 pm

Question 11

What is the hybridization of the nitrogen atom of pyridine?

A) s
B) sp
C) sp²
D) sp³

Question 12

Which of the following statements is not true about the structure of benzene?

A) the carbon-carbon bonds are all the same length
B) the structure rapidly transforms between two resonance contributors
C) the structure is an average of two resonance contributors
D) the ring of six carbon atoms is planar

Question 13

What is the correct assignment of the names of the following heterocycles?

A) 1 = pyrrole; 2 = thiophene; 3 = pyridine
B) 1 = thiophene; 2 = furan; 3 = pyrrole
C) 1 = furan; 2 = pyrrole; 3 = thiophene
D) 1 = furan; 2 = thiophene; 3 = pyrrole

Question 14

Which of the following compounds is aromatic?

A) ethane
B) cyclobutadiene
C) benzene
D) cyclooctatetraene

Question 15

What is the IUPAC name of the following compound?

A) 2-nitro-6-carboxybromobenzene
B) 2-bromo-1-nitro-4-benzoic acid
C) 2-bromo-4-carboxynitrobenzene
D) 3-bromo-4-nitrobenzoic acid

Question 16

Which is the correct assignment of the names of the following substituted benzenes?

A) 1 = phenol; 2 = m-cresol; 3 = toluene
B) 1 = m-cresol; 2 = resorcinol; 3 = m-xylene
C) 1 = anisole; 2 = catechol; 3 = m-xylene
D) 1 = m-cresol; 2 = anisole; 3 = cumene

Question 17

What is the correct assignment of the names of the following substituted benzenes?

A) 1 = styrene; 2 = benzaldehyde; 3 = cumene
B) 1 = anisole; 2 = benzaldehyde; 3 = toluene
C) 1 = styrene; 2 = xylene; 3 = toluene
D) 1 = aniline; 2 = phenol; 3 = cumene

Question 18

What is the IUPAC name of the following compound?

A) 1-bromo-2-fluoro-4-toluene
B) 4-bromo-2-fluorotoluene
C) 2-bromo-4-fluorophenol
D) 4-bromo-2-fluoroxylene

Question 19

What is the correct assignment of the names of the following substituted benzenes?

A) 1 = phenol; 2 = aniline; 3 = anisole
B) 1 = benzaldehyde; 2 = anisole; 3 = toluene
C) 1 = anisole; 2 = xylene; 3 = toluene
D) 1 = anisole; 2 = aniline; 3 = toluene

Question 20

What is the IUPAC name of the following compound?

A) 2,4-dibromotoluene
B) 2,4-dibromophenol
C) 2,4-dibromohydroxybenzene
D) 4,6-dibromophenol

Question 21

What is the major organic product obtained from the following reaction?

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

Question 22

Which of the following compounds is antiaromatic?

A) ethane
B) cyclobutadiene
C) benzene
D) cyclooctatetraene

Question 23

Which of the following has the compounds shown in the correct order of decreasing acidity (i.e., more acidic > less acidic)?

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

Question 24

What is the best choice of reagent to achieve the following reaction?

A) H₂SO₄
B) NaOH, H₂O
C) K₂Cr₂O₇, H₂SO₄
D) LiAlH₄

Question 25

Which of the following has the compounds shown in the correct order of decreasing acidity (i.e., more acidic > less acidic)?

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

Question 26

What is the major organic product obtained from the following reaction?

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

Question 27

What is the major organic product obtained from the following reaction?

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

Question 28

Which of the following compounds undergoes heterolytic carbon-halogen bond cleavage to form a stable organic cation?

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

Question 29

What is the best choice of reagent to achieve the following reaction?

A) H₂SO₄
B) NaOH, H₂O
C) K₂Cr₂O₇, H₂SO₄
D) H₂/Pd

Question 30

Which of the following ions is aromatic?

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

Question 31

What is the best choice of reagent to achieve the following reaction?

A) Br₂, CCl₄
B) HBr, H₂O
C) Br₂, light
D) NaBr

Question 32

Which of the following molecules is the most acidic?

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

Question 33

What is the major organic product obtained from the following reaction?

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

Question 34

Which of the following has the compounds shown in the correct order of decreasing acidity (i.e., more acidic > less acidic)?

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

Question 35

Which of the following has the compounds shown in the correct order of decreasing acidity (i.e., more acidic > less acidic)?

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

Question 36

Which of the following represents the energy levels of the molecular orbitals of cyclopentadienyl anion?

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

Question 37

Which of the following heterocycles is not aromatic?

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

Question 38

What is the major organic product obtained from the following reaction?

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

Question 39

Which of the following has the compounds shown in the correct order of decreasing acidity (i.e., more acidic > less acidic)?

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

Question 40

What is the major organic product obtained from the following reaction?

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

Question 41

Which of the following represents the energy levels of the molecular orbitals of cyclobutadiene?

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

Question 42

Which of the following is not true about [18]annulene?

A) [18]annulene is planar
B) [18]annulene is aromatic
C) [18]annulene gives one peak in the ¹H NMR spectrum
D) [18]annulene has 18 pi bonds

Question 43

Which of the following is not true about [the bridged [10]annulene shown below?

A) all of the carbon atoms of bridged [10]annulene are all in the same plane
B) bridged [10]annulene is aromatic
C) bridged [10]annulene undergoes substitution reactions similar to benzene
D) bridged [10]annulene has 10 pi electrons

Question 44

How many p orbital electrons are present in cyclopentadienyl anion?

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

Question 45

The product of the following reaction would be 1-bromo-1-phenylethane.

Question 46

What are the relative positions of the substituents in the following structure?

A) anti
B) meta
C) ortho
D) para

Question 47

What are the relative positions of the substituents in the following structure?

A) anti
B) meta
C) ortho
D) para

Question 48

How many p orbital electrons are present in furan?

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

Question 49

Phenols are stronger acids than alcohols because of the resonance stabilization of alkoxide ions.

Question 50

Furan has the structure shown below. The π orbitals in furan are shown below.

Question 51

The following compound should be name as 1-((1S, 3R)-3-methylcyclohexyl)benzene.

Question 52

Consider the following structures, A B
Structure A is more acidic than B.

Question 53

The product of the following reaction would be a dicarboxylic acid.

Question 54

Which of the following is not true about cyclooctatetraene?

A) The planar conformation is antiaromatic
B) In the planar conformation there are two electrons in degenerate nonbonding pi orbitals.
C) In the tub conformation the pi system is not conjugated
D) The tub conformation is aromatic

Question 55

What are the relative positions of the substituents in the following structure?

A) anti
B) meta
C) ortho
D) para

Question 56

Which of the following is true about [10]annulene?

A) [10]annulene is planar
B) [10]annulene is nonaromatic
C) [10]annulene undergoes addition reactions similar to simple alkenes
D) [10]annulene has 10 pi electrons

Question 57

The following compound is named (Z)-2,3-diphenyl-2-hexene.

Question 58

Which of the following does not undergo oxidation in the presence of H₂CrO₄?

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

Question 59

Consider the following structure. The ¹H NMR spectrum of this compound −60°C shows a peak at 7.6 ppm, this would indicate aromaticity.

Question 60

What is the intermediate in the reaction of ethylbenzene with NBS in the presence of benzoyl peroxide to give 1-bromo-1-phenylethane?

A) Benzylic anion
B) Benzylic cation
C) Benzylic radical
D) Benzylic carbene

Question 61

Why are nitrophenols more acidic than phenols?

Question 62

Assuming that the sulfur atom is sp²-hybridized, there are _____ π-electrons in the sulfathiazole ring.

Question 63

The following compound could be produced by reaction of phenol with bromobenzene.

Question 64

Identify the most acidic compound.

A)

B)

C)

D)

Question 65

Consider the following structure.
If named as an annulene, the name would be [ __ ] annulene.

Question 66

Consider the following general structure. Positions 1,4 and 2,6 and 3,5 are termed para, ortho, and meta, respectively.

Question 67

The ______ substituent is affected during the oxidation of 2-bromo-4-nitrotoulene using chromic acid.

A) methyl
B) nitro
C) bromo
D) hydroxy

Question 68

Which of the following compound is nonaromatic?

A)

B)

C)

D)

Question 69

List all of the requirements of a molecule for it to be considered aromatic.

Question 70

Consider the following structure.
This structure contains ____ π electrons.

Question 71

Provide a brief explanation of why the cyclopentadienyl anion (below) is aromatic. Your answer should identify the hybridization of each carbon atom and account for which electrons are in the pi system.

Question 72

Identify the major product of the following reaction. ​

A)

B)

C)

D)

Question 73

Provide a brief explanation of why furan (below) is aromatic. Your answer should identify the hybridization of the oxygen atom and account for which electrons are in the pi system.

Question 74

Using the Hückel criteria, the compound would be ______________.

Question 75

According to Hückel criteria, sulfathiazole is predicted to be ___________.

Question 76

Aspirin, also known as acetylsalicylic acid, is used to treat fever and inflammation. It is prepared from an unknown compound "A" by the process of esterification, using acetic anhydride. Identify compound "A".

A)

B)

C)

D)

Question 77

What is the chemical name of the following compound? ​

A) 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
B) 2,3-dichloro-5,6-dicyano-1,4-benzodione
C) 5,6-dicyano-2,3-dichloro-1,4-benzodione
D) 2,3-dicyano-5,6-dichloro-1,4-benzoquinone