Chapter 24 - Amines and Heterocycles
Drawing Instructions: Draw structures corresponding to each of the given names.
5. Draw: N,N-diisopropylamine
ANSWER:
POINTS: 1
6. Draw: N,N-dimethylcyclopentanamine
ANSWER:
POINTS: 1
7. Draw: 1,4-butanediamine
ANSWER: H2NCH2CH2CH2CH2NH2
POINTS: 1
8. Draw: p-methoxyaniline
ANSWER:
POINTS: 1
IUPAC Naming Instructions: Provide proper IUPAC names.
9. Name:
ANSWER: N-isopropyl-N-methylcyclobutylamine
POINTS: 1
10. Name:
ANSWER: 2,4-hexanediamine
POINTS: 1
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Chapter 24 - Amines and Heterocycles
11. Name:
ANSWER: methyl 2-aminobutanoate
POINTS: 1
12. Name:
ANSWER: N-ethylaniline
POINTS: 1
13. Name:
ANSWER: m-chloro-N,N-dimethylaniline
POINTS: 1
14. Name:
ANSWER: p-nitroaniline
POINTS: 1
Exhibit 24-3
Refer to the Table of pKas below to answer the following question(s):
pKas of Some Arylammonium Ions
Y
pKa
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Chapter 24 - Amines and Heterocycles
−H
−NH2
4.63
1.74
6.15
18. Refer to Exhibit 24-3. Based on the pKas for their corresponding ammonium ions, which arylamine above is the
strongest base?
ANSWER: p-aminoaniline
POINTS: 1
19. Refer to Exhibit 24-3. Explain the difference in acidity between p-cyanoanilinium ion and anilinium ion. Use both
words and structures.
ANSWER: p-Cyanoanilinium ion is a stronger acid (pKa = 1.74) than anilinium ion (pKa = 4.63). p-Cyanoanilinium ion
gives up a proton on nitrogen more readily than anilinium ion because the electron-withdrawing cyano group
polarizes the benzene ring and thus decreases the stability of the positively charged ion.
POINTS: 1
20. Refer to Exhibit 24-3. Explain the difference in acidity between p-aminoanilinium ion and anilinium ion. Use both
words and structures.
ANSWER: p-Aminoanilinium ion (pKa = 6.15) is less acidic than anilinium ion (pKa = 4.63) because p-aminoanilinium
ion is stabilized by the electron-donating amino group. The p-amino group donates electron density to the
benzene ring, which helps stabilize the positive charge on nitrogen.
POINTS: 1
21. Rank the following compounds in order of increasing basicity. Label the least basic compound "1" and the most basic
compound "4". Place the number corresponding to the compound's rank in the blank below the compound.
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Chapter 24 - Amines and Heterocycles
ANSWER:
POINTS: 1
22. When a THF solution of phenyl-2-propanone and bromobutane is treated with 50% aqueous NaOH, poor yields of 3phenyl-2-heptanone result. However, when a small amount of benzyltriethylammonium chloride is added to the reaction
mixture, the yield of 3-phenyl-2-heptanone increases to 90%. Explain these results.
ANSWER: The reaction that is occurring is a carbonyl α-substitution reaction. Hydroxide ion abstracts a proton from C-l
on phenyl-2-propanone to generate an enolate ion, which then undergoes SN2 attack at the primary carbon of
bromobutane. However, since the organic layer and water layer are immiscible, the hydroxide is unable to
come into contact with the ketone in the organic phase, so there is little or no reaction.
When the quaternary ammonium salt is added, it dissolves in both the aqueous and organic layers. When it
moves into the organic layer, it takes hydroxide ion with it, to preserve the charge neutrality. Once in the
organic layer, hydroxide ion reacts with the ketone to generate the enolate, which then undergoes SN2
displacement of bromide to give the carbonyl α-substitution product.
POINTS: 1
Exhibit 24-4
Refer to the reaction below to answer the following question(s):
24. Refer to Exhibit 24-4. This reaction is an example of:
a. a Curtius rearrangement
b. a Hofmann elimination reaction
c. a Gabriel synthesis
d. a Hofmann rearrangement
ANSWER: d
POINTS: 1
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Chapter 24 - Amines and Heterocycles
Exhibit 24-5
Give the major organic product(s) of each of the following reactions or sequences of reactions. Show all relevant
stereochemistry.
25.
ANSWER:
POINTS: 1
26.
ANSWER:
POINTS: 1
27.
ANSWER:
POINTS: 1
28.
ANSWER:
POINTS: 1
29.
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Chapter 24 - Amines and Heterocycles
ANSWER:
POINTS: 1
30.
ANSWER:
POINTS: 1
31.
ANSWER:
POINTS: 1
32.
ANSWER:
POINTS: 1
33.
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Chapter 24 - Amines and Heterocycles
ANSWER:
POINTS: 1
34.
ANSWER:
POINTS: 1
35.
ANSWER:
POINTS: 1
36.
ANSWER:
POINTS: 1
37.
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Chapter 24 - Amines and Heterocycles
ANSWER:
POINTS: 1
38.
ANSWER:
POINTS: 1
39.
ANSWER:
POINTS: 1
40.
ANSWER:
POINTS: 1
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Chapter 24 - Amines and Heterocycles
41.
ANSWER:
POINTS: 1
42.
ANSWER:
POINTS: 1
43.
ANSWER:
POINTS: 1
44.
ANSWER:
POINTS: 1
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Chapter 24 - Amines and Heterocycles
Exhibit 24-6
Show how each of the following transformations might be best accomplished. More than one step may be required. Show
all reagents and all intermediate structures.
47.
ANSWER:
POINTS: 1
48.
ANSWER:
POINTS: 1
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Chapter 24 - Amines and Heterocycles
49.
ANSWER:
POINTS: 1
50.
ANSWER:
POINTS: 1
Exhibit 24-7
Choose the best series of reactions for accomplishing each conversion below.
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Chapter 24 - Amines and Heterocycles
51.
a.
b.
c.
d.
ANSWER: c
POINTS: 1
52.
a.
b.
c.
d.
ANSWER: c
POINTS: 1
53.
a.
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Chapter 24 - Amines and Heterocycles
b.
c.
d.
ANSWER: a
POINTS: 1
54. Mescaline is a hallucinogenic alkaloid isolated from peyote cactus. Synthesize mescaline from 3,4,5trimethoxytoluene. Show all reagents and all intermediate structures.
ANSWER:
POINTS: 1
Exhibit 24-8
Refer to the data below to answer the following question(s):
Triclocarban is a disinfectant prepared from 3,4-dichloroaniline and 4-chlorophenylisocyanate.
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Chapter 24 - Amines and Heterocycles
55. Refer to Exhibit 24-8. Prepare 4-chlorophenylisocyanate from toluene.
ANSWER:
POINTS: 1
56. Refer to Exhibit 24-8. Prepare 3,4-dichloroaniline from benzene.
ANSWER:
POINTS: 1
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Chapter 24 - Amines and Heterocycles
58. From the list provided below, choose the best reagent(s) for each step in the following synthesis. There is only one
answer for each reaction.
a. NaBH4, ethanol
b. KCN, acetone
c. 1.
2.
d.
LiAlH4, THF
H2O
1. HNO2, H2SO4
2. CuCN, KCN
e. 1. SnCl2, H3O+
2. NaOH, H2O
f. HNO3, H2SO4
ANSWER: step 1 = e; step 2 = d; step 3 = c
POINTS: 1
59. Draw the structures for each of the intermediates in the boxes provided for the synthesis below.
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Chapter 24 - Amines and Heterocycles
ANSWER:
POINTS: 1
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