Deck 15: Benzene and Aromaticity

Question 1

Exhibit 15-2
Answer the following question(s) concerning sulfathiazole,below.
Refer to Exhibit 15-2.What reactivity do you predict for sulfathiazole?

Answer 1

Sulfathiazole is predicted to have aromatic reactivity since it is cyclic,planar,conjugated and has six π-electrons.

Question 2

Name:

Answer 2

(1-methylethyl) benzene or isopropylbenzene or cumene

Question 3

Name:

Answer 3

1-((1S,3R)-3-methylcyclohexyl)benzene

Question 4

Draw: 3,5-dimethylbenzoic acid

Question 5

Exhibit 15-3
Refer to the data below to answer the following question(s).
The ¹H NMR spectrum of [14]annulene at −60°C shows two signals,one at 0 ppm and one at 7.6 ppm,with an area ratio of 5:2.
Refer to Exhibit 15-3.Is [14]annulene aromatic?

Question 6

Name:

Question 7

Draw: p-chlorobenzaldehyde

Question 8

Exhibit 15-2
Answer the following question(s) concerning sulfathiazole,below.
Refer to Exhibit 15-2.What is the hybridization of the nitrogen atom in sulfathiazole?

Question 9

Exhibit 15-4
Consider the data below to answer the following question(s).
Refer to Exhibit 15-4.Conjugate bases QB and ZB are both resonance stabilized.Draw the indicated number of resonance forms for QB and ZB.

Question 10

Draw: 1-phenyl-3-methylpentane

Question 11

Exhibit 15-3
Refer to the data below to answer the following question(s).
The ¹H NMR spectrum of [14]annulene at −60°C shows two signals,one at 0 ppm and one at 7.6 ppm,with an area ratio of 5:2.
Refer to Exhibit 15-3.Draw in the protons on the [14]annulene skeleton provided below which are responsible for the ¹H NMR signal at 0 ppm.

Question 12

Name:

Question 13

Name:

Question 14

Most alkyl halides are nonpolar covalent compounds and,therefore,are soluble in nonpolar solvents and insoluble in water.Cycloheptatrienyl bromide is an unusual alkyl halide in that it is insoluble in nonpolar solvents,but is readily soluble in water! This behavior is consistent with cycloheptatrienyl bromide being an ionic compound.Why does cycloheptatrienyl bromide exist as an ionic compound? Explain by comparing the covalent structure to the ionic structure.

Question 15

Draw: p-bromoaniline

Question 16

Exhibit 15-3
Refer to the data below to answer the following question(s).
The ¹H NMR spectrum of [14]annulene at −60°C shows two signals,one at 0 ppm and one at 7.6 ppm,with an area ratio of 5:2.
Refer to Exhibit 15-3.Explain why these protons have absorption at such high fields.

Question 17

Draw: o-chlorophenol

Question 18

Draw: m-fluoronitrobenzene

Question 19

Exhibit 15-4
Consider the data below to answer the following question(s).
Refer to Exhibit 15-4.Which of the compounds above,Q or Z,would you predict to be most acidic? Explain your answer.

Question 20

Exhibit 15-2
Answer the following question(s) concerning sulfathiazole,below.
Refer to Exhibit 15-2.Assuming that the sulfur atom is sp²-hybridized,how many π-electrons are there in the sulfathiazole ring?

Question 21

Draw a picture of the π orbitals in furan (shown below).Is furan aromatic?

Question 22

Exhibit 15-5
Consider the data below to answer the following question(s).
C₉H₁₂;¹H NMR:
7.18 δ (broad singlet,5H)
2.55 δ (triplet,2H)
1.70 δ (sextet,2H)
0.9 δ (triplet,3H)
Refer to Exhibit 15-5.Describe the signal at 7.18 δ in terms of its splitting,integration and chemical shift.

Question 23

Exhibit 15-5
Consider the data below to answer the following question(s).
C₉H₁₂;¹H NMR:
7.18 δ (broad singlet,5H)
2.55 δ (triplet,2H)
1.70 δ (sextet,2H)
0.9 δ (triplet,3H)
Refer to Exhibit 15-5.Describe the signal at 2.55 δ in terms of its splitting,integration,and chemical shift.

Question 24

Explain in terms of MO theory,why systems with 4n + 2 π electrons are aromatic and with 4n π electrons are antiaromatic.

Question 25

Exhibit 15-5
Consider the data below to answer the following question(s).
C₉H₁₂;¹H NMR:
7.18 δ (broad singlet,5H)
2.55 δ (triplet,2H)
1.70 δ (sextet,2H)
0.9 δ (triplet,3H)
Refer to Exhibit 15-5.Describe the signal at 0.9 δ in terms of its splitting,integration and chemical shift.

Question 26

Exhibit 15-7
Consider the data below to answer the following question(s).
C₇H₇ClO;IR absorption at 810 cm−¹ Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
Refer to Exhibit 15-7.Calculate the degrees of unsaturation for this compound.

Question 27

Consider the following compound.Atoms other than carbon and hydrogen are labeled. Which of the following is not valid?

A)naming of the parent compound,benzene.
B)1,4-disubstitution is present.
C)para prefix applicable.
D)classified as aromatic.

Question 28

What is the structure of a hydrocarbon that shows a molecular ion at m/z = 182 in the mass spectrum and has the following ¹H NMR spectrum?
7.2 δ,singlet,5H
2.9 δ,singlet,2H

Question 29

Give the IUPAC name for:

Question 30

Exhibit 15-7
Consider the data below to answer the following question(s).
C₇H₇ClO;IR absorption at 810 cm−¹ Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
Refer to Exhibit 15-7.What is the significance of an IR absorption at 810 cm−¹?

Question 31

How many monosubstituted products would you expect for the bromination of naphthalene?

A)2
B)4
C)6
D)8

Question 32

Exhibit 15-5
Consider the data below to answer the following question(s).
C₉H₁₂;¹H NMR:
7.18 δ (broad singlet,5H)
2.55 δ (triplet,2H)
1.70 δ (sextet,2H)
0.9 δ (triplet,3H)
Refer to Exhibit 15-5.Describe the signal at 1.70 δ in terms of its splitting,integration and chemical shift.

Question 33

Exhibit 15-6
Consider the data below to answer the following question(s).
C₉H₁₂;¹H NMR:
6.65 δ (singlet,3H)
2.25 δ (singlet,9H)
Refer to Exhibit 15-6.Describe the signal at 6.65 δ in terms of its splitting,integration and chemical shift.

Question 34

Draw the resonance structures of cyclooctatetraene.

Question 35

Draw the MO energy diagram for the cycloheptatrienyl anion and classify the anion as aromatic or antiaromatic.

Question 36

Exhibit 15-7
Consider the data below to answer the following question(s).
C₇H₇ClO;IR absorption at 810 cm−¹ Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
Refer to Exhibit 15-7.Describe the signal at 3.7 δ in terms of its splitting,integration and chemical shift.

Question 37

Exhibit 15-6
Consider the data below to answer the following question(s).
C₉H₁₂;¹H NMR:
6.65 δ (singlet,3H)
2.25 δ (singlet,9H)
Refer to Exhibit 15-6.Describe the signal at 2.25 δ in terms of its splitting,integration and chemical shift.

Question 38

Exhibit 15-6
Consider the data below to answer the following question(s).
C₉H₁₂;¹H NMR:
6.65 δ (singlet,3H)
2.25 δ (singlet,9H)
Refer to Exhibit 15-6.Propose a structure for this compound.

Question 39

Exhibit 15-7
Consider the data below to answer the following question(s).
C₇H₇ClO;IR absorption at 810 cm−¹ Spectrum obtained from: SDBSWeb: http://www.aist.go.jp/RIODB/SDBS/
Refer to Exhibit 15-7.Propose a structure for this compound.

Question 40

Exhibit 15-5
Consider the data below to answer the following question(s).
C₉H₁₂;¹H NMR:
7.18 δ (broad singlet,5H)
2.55 δ (triplet,2H)
1.70 δ (sextet,2H)
0.9 δ (triplet,3H)
Refer to Exhibit 15-5.Propose a structure for this compound.

Question 41

​Draw the different resonance forms of phenanthrene.

Question 42

What m/z ratio range might be common to many substituted benzene compounds?

A)72 - 77 ppm
B)26 - 38 ppm
C)81 - 88 ppm
D)less than 59 ppm

Question 43

​Draw the resonance forms of indene.

Question 44

Which of the following does not correctly characterize this compound represented by the molecular model shown below? Atoms other than carbon and hydrogen are labeled. ​

A)slightly acidic
B)named as isopropyl o-cresol
C)contains aryl,alkyl and benzylic proton
D)would produce a signal due to dehydration in a mass spectrum
E)All of the above characterize this compound.

Question 45

Which of the following aromatic compounds will have largest number of signals in a ¹³CNMR?

A)1,4-dimethylbenzene (p-methyl toluene)
B)1,3,5-trimethylbenzene (mesitylene)
C)1,2,4,5-tetramethylbenzene
D)All produce the same number of signals.

Question 46

Which of the choices arranges numbered protons in the following substance in order of increasing downfield chemical shift in a proton NMR? Atoms other than carbon and hydrogen are labeled.

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

Question 47

​Draw the different resonance forms of anthracene.