Question 1

Which of the following statements about benzene is true?&#10;A)Benzene is a saturated hydrocarbon.&#10;B)Benzene undergoes addition reactions.&#10;C)Benzene has five degrees of unsaturation.&#10;D)Benzene undergoes substitution reactions.

Accepted Answer

Benzene undergoes substitution reactions, in which one or more hydrogen atoms on the ring are replaced by a functional group. This is due to its unsaturated structure, which consists of alternating double bonds. Benzene is not a saturated hydrocarbon, as it contains multiple bonds. It has only three degrees of unsaturation, as each double bond is counted as one degree. It does not undergo addition reactions, as the high stability of its ring structure makes it difficult to break the multiple bonds and add new groups.

Question 2

What is the correct assignment of the names of the following fused aromatic compounds?  &#10;A)I = naphthalene; II = anthracene; III = phenanthrene&#10;B)I = naphthalene; II = phenanthrene; III = anthracene&#10;C)I = naphthalene; II = phenanthrene; III = benzo[a]pyrene&#10;D)I = anthracene; II = naphthalene; III = phenanthrene

Accepted Answer

The compound consists of two fused rings, a benzene and a naphthalene. The benzene ring is ortho to the left-hand side of the naphthalene ring, and the compound is named as follows:

The naphthalene ring is numbered as shown, beginning at the top left carbon and continuing clockwise. The benzene ring is placed at the 1,6-positions of the naphthalene ring. Therefore, the compound is named as 1-benzonaphtho[2,3-b]anthracene.

Similarly, the bottom right carbon on the naphthalene ring is assigned a higher priority than the top left carbon of the benzene ring, and this gives rise to the 11a- prefix. Hence the correct option is A.

Question 3

What is the correct assignment of the names of the following substituted benzenes?  &#10;A)I = Phenol; II = anisole; III = toluene&#10;B)I = Benzaldehyde; II = phenol; III = anisole&#10;C)I = Benzaldehyde; II = phenol; III = toluene&#10;D)I = Phenol; II = anisole; III = styrene

Accepted Answer

The compound I has a -CHO group which indicates benzaldehyde. The compound II has an -OH group which indicates phenol. The compound III has a -CH3 group and no other functional groups, indicating toluene. Therefore, the correct assignment of names is I = benzaldehyde, II = phenol, and III = toluene.

Question 4

What is the correct assignment of the names of the following substituted benzenes?  &#10;A)I = Styrene; II = aniline; III = anisole&#10;B)I = Toluene; II = anisole; III = styrene&#10;C)I = Styrene; II = anisole; III = phenol&#10;D)I = Toluene; II = aniline; III = anisole

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Question 5

What is the IUPAC name of the following compound?  &#10;A)3,6-Dichloroaniline&#10;B)2,5-Dichloroaniline&#10;C)2,5-Dichloroaminobenzene&#10;D)2,5-Dichloroanisole

Accepted Answer

The compound has two chlorine atoms attached to the benzene ring at positions 2 and 5. The parent compound is aniline (a benzene ring with an amino group), so the name should reflect the addition of the two chlorine atoms as substituents. The correct way to number the benzene ring follows the lowest to highest priority rule for substituent numbering, resulting in the name 2,5-dichloroaniline. Choice A is incorrect because it has the wrong positional numbers for the substituents, and choice C is incorrect because it uses the suffix "-aminobenzene" instead of "-aniline." Choice D is incorrect because it uses the suffix "-anisole" instead of "-aniline."

Question 6

What orbitals are used to form the bond indicated in the following molecule? A)Csp²¾Csp² B)Csp²¾ C2p C)C2p¾C2p D)Csp³¾Csp³

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Question 7

What is the IUPAC name of the following compound?  &#10;A)3-Bromo-1-chloro-4-toluene&#10;B)2-Bromo-4-chlorotoluene&#10;C)4-Chloro-2-bromo-1-toluene&#10;D)2-Bromo-4-chloroanisole

Accepted Answer

The parent chain is toluene (methylbenzene) with bromine at the 2 position and chlorine at the 4 position, giving the name 2-bromo-4-chlorotoluene.

Question 8

Which of the following molecules has the most acidic hydrogen atoms?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

Accepted Answer

The most acidic hydrogen atom is one that can be easily removed in a dissociation reaction. In molecule I, the hydrogen atom is bonded to a carbon atom which is bonded to an sp3 hybridized carbon atom. This makes the hydrogen less acidic compared to molecule III, where the hydrogen atom is attached to an sp hybridized carbon, making it more acidic. Therefore, the correct answer is molecule III.

Question 9

Rank the following compounds in order of decreasing acidity,starting with the most acidic.  &#10;A)I > II > III&#10;B)III > II > I&#10;C)III > I > II&#10;D)I > III > II

Accepted Answer

The acidity of a compound is determined by the stability of its conjugate base. The more stable the conjugate base, the stronger the acid. In this case, compound III has a resonance-stabilized conjugate base, making it the strongest acid. Compound II also has a resonance structure in its conjugate base, but it is not as stable as the one for III. Compound I does not have any resonance stabilization in its conjugate base, making it the weakest acid. Therefore, the correct order of decreasing acidity is III > II > I, which is represented by choice B.

Question 10

What is the correct assignment of the number of signals in the ¹³C NMR spectra of the following disubstituted benzene derivatives? A)I = 3 signals; II = 3 signals; III = 2 signals B)I = 3 signals; II = 4 signals; III = 2 signals C)I = 6 signals; II = 6 signals; III = 6 signals D)I = 3 signals; II = 4 signals; III = 3 signals

Accepted Answer

Based on the spectral notation, the disubstituted benzene derivatives have the following substituents: I: One substituent at position 1 and two substituents at position 3 II: Two substituents at position 1 and one substituent at position 4 III: Two substituents at position 1 and one substituent at position 2 For I, there will be three signals since the two substituents at position 3 are equivalent and will produce a single signal, while the substituent at position 1 will produce two signals due to its nonequivalence with the equivalent substituents at position 3. For II, there will be four signals since the two substituents at position 1 are non-equivalent and will each produce a separate signal, while the substituent at position 4 will produce a single signal. For III, there will be two signals since the two substituents at position 1 are equivalent and will produce a single signal, while the substituent at position 2 is far enough away to not impact the NMR spectrum significantly. Therefore, the correct assignment of the number of signals in the ¹³C NMR spectra of the disubstituted benzene derivatives is: I = 3 signals; II = 4 signals; III = 2 signals. Hence, the best choice is B.

Question 11

What is the IUPAC name of the following compound?  &#10;A)2-Nitro-5-carboxychlorobenzene&#10;B)2-Chloro-4-carboxynitrobenzene&#10;C)2-Chloro-1-nitro-4-benzoic acid&#10;D)3-Chloro-4-nitrobenzoic acid

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Question 12

What is the structure of a compound of molecular formula C₁₀H₁₄O₂ that shows a strong IR absorption at 3150 ¾2850 cm^-1 and gives the following ¹H NMR absorptions: 1.4 (triplet,6H); 4.0 (quartet,4H); and 6.8 (singlet,4H)ppm?

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

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Question 13

How many ¹³CNMR signals does the following compound exhibit? A)4 B)5 C)6 D)8

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Question 14

Which of the following statements about the structure of benzene is not true?&#10;A)Benzene is planar.&#10;B)Benzene has three short double bonds alternating with three longer single bonds.&#10;C)The electrons in the pi bonds are delocalized around the ring.&#10;D)Benzene has six pi electrons.

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Question 15

Which of the following is not a criterion for antiaromaticity?&#10;A)The molecule must be cyclic.&#10;B)The molecule must have (4n + 2)pi electrons.&#10;C)The molecule must be planar.&#10;D)The molecule must be completely conjugated.

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Question 16

What is the correct assignment of the names of the following aromatic heterocycles?  &#10;A)I = pyridine; II = pyrimidine; III = furan&#10;B)I = pyrimidine; II =pyrrole; III = furan&#10;C)I = pyridine; II = pyrrole; III = furan&#10;D)I = pyrimidine; II = pyrrole; III = tetrahydrofuran

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Question 17

Which of the following ions is aromatic?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 18

What is the IUPAC name of the following compound?  &#10;A)1-Chloro-4-ethyl-3-propylbenzene&#10;B)1-Chloro-4-ethyl-5-propylbenzene&#10;C)4-Chloro-1-ethyl-2-propylbenzene&#10;D)4-Chloro-2-propyltoluene

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Question 19

Which of the following heterocycles is not aromatic?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 20

Which of the following is not one of the H&#252;ckel's criteria for aromaticity?&#10;A)The molecule must be cyclic.&#10;B)The molecule must be planar.&#10;C)The molecule must be completely conjugated.&#10;D)The molecule must have 4n pi electrons.

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Question 21

Why is the following compound not aromatic?  &#10;A)It has 4n pi electrons.&#10;B)It is not cyclic.&#10;C)It has 4n+2 pi electrons.&#10;D)The pi electron system is not continuous.

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Question 22

Which of the following compounds is aromatic?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 23

What is the name of the following compound?  &#10;A)2,6-Dimethylbenzene&#10;B)5-Methyltoluene&#10;C)Anisole&#10;D)1,3-Dimethylbenzene

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Question 24

Which of the following ions is aromatic?  &#10;A)Only I and II&#10;B)Only II and III&#10;C)Only III and IV&#10;D)Only II and IV

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Question 25

What compound is consistent with the following ¹H NMR spectrum? A)Phenol B)Anisole C)4-bromoanisole D)4-bromotoluene

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Question 26

What is the correct structure for anisole?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 27

Why is the following compound not aromatic?  &#10;A)It has 4n electrons.&#10;B)It is not cyclic.&#10;C)It has 4n+2 electrons.&#10;D)The pi electron system is not continuous.

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Question 28

What is the correct structure for para-bromotoluene?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 29

What is the name of the following compound?  &#10;A)Meta-bromophenol&#10;B)Para-hydroxybenzene&#10;C)3-bromoanisole&#10;D)6-methoxy-2-bromobenzene

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Question 30

Which of the following compounds is not aromatic?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 31

What is the correct structure for 1-bromo-2,4-dimethoxybenzene?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 32

What orbitals are used to form the indicated bond? A)sp³ B)sp² C)p D)sp³ and sp²

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Question 33

Which of the following statements about the molecular orbital (MO)theory is true?  &#10;A)When two p orbitals of similar phase overlap side-by-side,a p* antibonding molecular orbital is formed.&#10;B)When two p orbitals of opposite phase overlap side-by-side,a p bonding molecular orbital is formed.&#10;C)A p bonding molecular orbital is higher in energy than the two atomic p orbitals from which it is formed.&#10;D)A p* antibonding molecular orbital is higher in energy than the two atomic p orbitals from which it is formed.

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Question 34

How many different proton signals would the following compound show in its ¹H NMR spectrum? A)1 B)3 C)5 D)6

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Question 35

Which of the following compounds is not aromatic?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 36

Which of the following compounds is aromatic?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 37

Where do the protons in benzene appear in the ¹H NMR spectrum? A)Around 1600 cm^-1 B)Around 120 ppm C)Around 0 ppm D)Around 7 ppm

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Question 38

What orbitals are used to form the indicated bond? A)sp³ B)sp² C)p D)sp³ and sp²

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Question 39

What is the correct structure for toluene?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 40

What is the correct structure for aniline?  &#10;A)I&#10;B)II&#10;C)III&#10;D)IV

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Question 41

What is the IUPAC name of the following compound?  &#10;A)o-nitroaniline&#10;B)m-nitroaniline&#10;C)p-nitroaniline&#10;D)4-nitroanilsole

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Question 42

What is the IUPAC name of the following compound?  &#10;A)o-nitrotoluene&#10;B)m-nitrotoluene&#10;C)p-nitrotoluene&#10;D)3-nitroanisole

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Question 43

In what type of orbital does the lone pair on the indicated N atom reside? A)p B)sp C)sp² D)sp³

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Question 44

What is the hybridization of the indicated N atom in the following compound? A)p B)sp C)sp² D)sp³

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Question 45

What is the hybridization of the indicated N atom in the following compound? A)p B)sp C)sp² D)sp³

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Question 46

What is the IUPAC name of the following compound?  &#10;A)o-nitroanisole&#10;B)m-nitroanisole&#10;C)p-nitroanisole&#10;D)2-nitroaniline

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Question 47

In what type of orbital does the lone pair on the indicated N atom reside? A)p B)sp C)sp² D)sp³

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Deck 15: Benzene and Aromatic Compounds