Deck 16: The Chemistry of Benzene and Its Derivatives

Question 1

Give the IUPAC name for the compound.

Answer 1

The compound is named 1,3-dibromo-5-methylbenzene. Alternatively, the parent name could include the methyl group in the benzene ring. The alternative name would be 3,5-dibromotoluene.

Question 2

Give the IUPAC name for the compound.

Answer 2

The benzene ring has a hydroxy substituent, so will have the parent name phenol. The hydroxy will have the highest priority, so it will receive the lowest locant numbering. Thus, the methoxy will be on carbon 3 and the chloro group on carbon 4. The complete name is thus 4-chloro-3-methoxyphenol.

Question 3

Select the correct name for PhCH₂Br.

A) bromobenzene
B) bromobenzyl
C) phenyl bromide
D) benzyl bromide

Answer 3

D

Question 4

A reaction forms the ortho, meta, and para isomers of dibromobenzene. Draw the structures of the three compounds and explain how you can use the melting point to separate the mixtures. Which would you expect to have the highest melting point?

Question 5

Which of these statements is not true about the electrophilic bromination of benzene?

A) The reaction intermediate has an sp³ hybridized carbon.
B) A carbocation intermediate is formed in the rate limiting (slow) step of the reaction.
C) Aromaticity is regained when a proton is removed in the final step of the reaction.
D) Benzene functions as a nucleophile in the reaction.
E) A frequent by-product of the reaction is the normal bromine addition product seen with alkenes.

Question 6

Which compound reacts slowest during nitration?

A) compound A
B) compound B
C) compound C
D) compound D
E) compound E

Question 7

Which of these is a meta-directing group that is also an activator?

A) -CHO
B) -I
C) -NMe₃⁺
D) -NO₂
E) there are no meta-directing activators

Question 8

Which compound would be the most reactive towards ring bromination?

A) compound A
B) compound B
C) compound C
D) compound D
E) compound E

Question 9

Indicate the missing products of the reaction. When filling in the product indicate only the major organic product(s). There may be more than one acceptable answer. If you believe no reaction would occur, write NR. Denote stereochemistry where appropriate.

Question 10

Provide detailed, arrow-pushing mechanisms for the transformation. Show all reactive intermediates. (It is not necessary to show every resonance structure for appropriate intermediates.)

Question 11

The -NH₂ group is an ortho/para-director. So, explain why the reaction is observed experimentally. Use structures and 15 words or less.

Question 12

Indicate whether the compound should undergo nitration more rapidly or more slowly than benzene and give the structure of the major mononitration product. Explain, using a few words and structures.

Question 13

Indicate whether the compound should undergo nitration more rapidly or more slowly than benzene and give the structure of the major mononitration product. Explain, using a few words and structures.

Question 14

Devise a two-step synthesis to form the product from benzene. The intermediate is a substituted benzene with a ¹H NMR singlet at $\delta$ 2.5 ppm. Identify the intermediate.

Question 15

Draw the major organic product for the reaction.

Question 16

For each set, circle the faster of the two reactions.
a.
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b.

Question 17

Indicate whether the compound would undergo nitration more rapidly or more slowly than toluene (also known as methylbenzene) and give the structure of the major mononitration product. Explain, using a few words and structures.

Question 18

Indicate whether the compound would undergo nitration more rapidly or more slowly than toluene (also known as methylbenzene) and give the structure of the major mononitration product. Explain, using a few words and structures.

Question 19

Write a mechanism for this reaction. Show the formation of major product (in ortho and para situations, just show one, not both). Using structures, and 10 words or less, explain clearly why substitution occurs in the position you indicated over any of the other positions.

Question 20

Write a mechanism for this reaction. Show the formation of major product (in ortho and para situations, just show one, not both). Using structures, and 10 words or less, explain clearly why substitution occurs in the position you indicated over any of the other positions.

Question 21

Draw the major organic product for the reaction. The product should be one compound with 11 carbons.

Question 22

Explain how you would distinguish between three isomers with the molecular formula C₉H₁₂ using only ¹H NMR spectroscopy.

Question 23

Deduce the structure of an unknown compound with the molecular formula C₁₀H₁₄O and the following proton NMR data:
$\delta$ 7.39 (d, 2H, J = 7 Hz), 6.93 (d, 2H, J = 7 Hz), 3.81 (s, 3H), 2.87 (septet, 1H, J = 6.8 Hz), 1.20 (d, 6H, J = 6.8 Hz).

Question 24

Outline a synthesis of this compound from benzene.