Deck 15: Benzene and Aromaticity: Electrophilic Aromatic Substitution

Question 1

Which of the following carbocations would you expect to be most stable?

A)

B)

C)

D)

E)

Answer 1

Question 2

How would you name the following?

A) 3-chloro-5-methylphenol
B) 3-hydroxy-5-chlorotoluene
C) 1-chloro-3-hydroxy-5-methylbenzene
D) Meta-methy-meta-hydroxytoluene
E) 3-hydroxy-5-methylchlorobenzene

Answer 2

3-chloro-5-methylphenol

Question 3

Which of the following would not be aromatic (i.e.,which would not be unusually stable)?

A)

B)

C)

D)

E)

Answer 3

Question 4

Which of the following molecules would you predict to be aromatic?

A)

B)

C)

D)

E)

Question 5

What is the common name for the following compound?

A) Toluene
B) Anisole
C) Aniline
D) Phenol
E) Cresol

Question 6

The best experimental proof of aromaticity is

A) a pleasant odor.
B) infrared CH absorption frequency.
C) NMR chemical shifts.
D) presence of resonance structures.
E) presence of conjugation.

Question 7

Which of the following is not a resonance structure involved in electrophilic aromatic bromination?

A)

B)

C)

D)

E) All of these are valid resonance structures.

Question 8

What would be the expected product of the following reactions?

A)

B)

C)

D)

E)

Question 9

Which of the following would you expect to be aromatic?

A)

B)

C)

D)

E)

Question 10

Which of the following reactions of aromatics is reversible?

A) Nitration
B) Bromination
C) F-C alkylation
D) Sulfonation
E) F-C acylation

Question 11

Which of the following reactions has an aromatic transition state with (4n + 2)electrons involved?

A)

B)

C)

D) Two of these.
E) All of these.

Question 12

What reagents are typically required to accomplish bromination of an aromatic ring?

A) Br₂ + HBr
B) Br₂ + heat
C) Br₂ + light
D) Br₂ + FeBr₃
E) Br₂ + H₂SO₄

Question 13

How many mononitrated (on the aromatic ring)derivatives of meta-xylene (= 1,3-dimethylbenzene)are possible? (Don't worry about how they might be made or which would be the major product.)

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

Question 14

Which of the following would you expect to react fastest in an S_N1 reaction (consider the mechanism)?

A)

B)

C)

D) All would react rapidly.
E) None would react.

Question 15

What is/are the major product(s)in the following reaction?

A)

B)

C)

D) Both A and C
E) No Reaction

Question 16

Which would be the best systematic name of vanillan,the primary flavoring ingredient in vanilla?

A) 4-formyl-2-methoxyphenol
B) 3-formyl-6-hydroxyanisole
C) 4-hydroxy-3-methoxybenzaldehyde
D) 5-formyl-2-hydroxyanisole
E) 4-formyl-5-methoxyphenol

Question 17

The reagents listed below all react readily with alkenes.Which one can react (slowly)irreversibly with an aromatic ring?

A) HBr + peroxides
B) CH₃CO₃H
C) HBr
D) H₂/catalyst
E) H₂O,H⁺

Question 18

One of the double bonds in phenanthrene,shown below,is much more reactive than the others.Which one is it?

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

Question 19

Which of the following best describes the electronic nature of cyclooctatetraene?

A) This compound is predicted to be aromatic.
B) This compound is anti-aromatic and very unstable.
C) This compound is non-planar and non-aromatic.
D) Not all of the carbon atoms possess the $\pi$ -orbital required for conjugation.
E) None of these are true.

Question 20

What would be the product of the following reaction?

A)

B)

C)

D)

E) No reaction occurs.

Question 21

What is the major product of the following reaction?

A)

B)

C)

D)

E) no reaction

Question 22

The infrared spectrum of a dimethylbenzene has a band at 738 cm^-1.What is the most likely structure of the compound?

A) 1,2-dimethylbenzene
B) 1,3-dimethylbenzene
C) 1,4-dimethylbenzene
D) 1,5-dimethylbenzene
E) Not enough information to determine

Question 23

Which of the following statements are not true of benzene?

A) The carbon-carbon bond lengths alternated between single bonds and double bonds.
B) All carbons are sp² hybridized.
C) The delocalized electrons form a circular pi-cloud above and below the ring.
D) It is especially stable according to heats of hydrogenation data.
E) None of the above.All of these statements are true.

Question 24

What is/are the product(s)in the following Friedel-Crafts Reaction?

A)

B)

C)

D) Both A and B.
E) All of the above.

Question 25

Which of the following is not an allotrope of carbon?

A) Graphite
B) Diamond
C) Coal
D) C₆₀
E) All are allotropes of carbon.

Question 26

If the heat of hydrogenation of the hypothetical 1,3,5-cyclohexatriene is -78.9 kcal/mol,but the heat of hydrogenation of benzene is -49.3 kcal/mol,what is the stabilization energy attributed to the resonance in benzene?

A) -49.3 kcal/mol + (-78.9 kcal/mol)= -128.2 kcal/mol
B) -49.3 kcal/mol - (-78.9 kcal/mol)= 29.6 kcal/mol
C) -49.3 kcal/mol
D) -78.9 kcal/mol
E) None of the above.

Question 27

What is/are the product(s)from the following reaction?

A)

B)

C)

D)

E)

Question 28

Which of the following mechanisms best describes electrophilic aromatic substitution of benzene with bromine?

A)

B)

C)

D)

E) None of the above.

Question 29

Which of the following molecular orbitals corresponds to the $\Psi$ ₁ molecular orbital of benzene?

A)

B)

C)

D)

E) None of the above.