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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W
Short Answer
Exhibit 24-1
Classify each of the following nitrogen atoms in the following compounds as primary, secondary, tertiary, or
quaternary.

1.

2.

3.

4.
Drawing Instructions: Draw structures corresponding to each of the given names.
5. Draw: diisopropylamine
6. Draw: N,N-dimethylcyclopentanamine
7. Draw: 1,4-butanediamine
IUPAC Naming Instructions: Provide proper IUPAC names.

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


8. Name:

9. Name:

10. Name:

11. Name:

12. Name:

Exhibit 24-2
Consider the reaction below to answer the following question(s).
Methamphetamine can be synthesized by reacting phenyl-2-propanone with methylamine in the presence of
H2/Ni.

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


13. Refer to Exhibit 24-2. Identify the nucleophile in the initial reaction of phenyl-2-propanone to yield
intermediate A.
14. Refer to Exhibit 24-2. Although the yield of methamphetamine is good, some unreacted phenyl-2-propanone
remains after the reaction is complete. Describe how methamphetamine can be separated from
phenyl-2-propanone.
Exhibit 24-3
Refer to the Table of pKas below to answer the following question(s):
pKas of Some Arylammonium Ions

Y
H
NH2

pKa
4.63
1.74
6.15

15. Refer to Exhibit 24-3. Explain the difference in acidity between p-cyanoanilinium ion and anilinium ion. Use
both words and structures.
16. Refer to Exhibit 24-3. Explain the difference in acidity between p-aminoanilinium ion and anilinium ion. Use
both words and structures.
17. 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.

18. When a THF solution of phenyl-2-propanone and bromobutane is treated with 50% aqueous NaOH, poor
yields of 3-phenyl-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.

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


Exhibit 24-4
Refer to the reaction below to answer the following question(s):

19. Refer to Exhibit 24-4. Draw arrows on the structures provided below which show electron flow in the
complete stepwise mechanism for the reaction above.

20. Refer to Exhibit 24-4. This reaction is an example of:
a.
b.
c.

a Curtius rearrangement

a Hofmann elimination reaction
a Gabriel synthesis

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


d.

a Hofmann rearrangement

Exhibit 24-5
Give the major organic product(s) of each of the following reactions or sequences of reactions. Show all
relevant stereochemistry.

21.

22.

23.

24.

25.

26.

27.

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


28.

29.

30.

31.

32.

33.
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.

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


34.

35.

36.

37.
Exhibit 24-7
Choose the best series of reactions for accomplishing each conversion below.

38.
a.
b.
c.

d.

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


39. Mescaline is a hallucinogenic alkaloid isolated from peyote cactus. Synthesize mescaline from
3,4,5-trimethoxytoluene. Show all reagents and all intermediate structures.

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.

40. Refer to Exhibit 24-8. Prepare 4-chlorophenylisocyanate from toluene.

41. Refer to Exhibit 24-8. Prepare 3,4-dichloroaniline from benzene.

42. Draw the structures for each of the intermediates in the boxes provided for the synthesis below.

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


43. Name the following substance. Atoms other than carbon and hydrogen are labeled.

44. Draw the product of the reaction of the following substance with 1.) LiAlH4 in ether, 2.) H2O with the
following substance. From what alkyl bromide could this substance be produced when reacted with NaCN?
Atoms other than carbon and hydrogen are labeled.

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


45. Write the equation for the reaction represented by the pKa of methyl amine.

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W

Answer Section
SHORT ANSWER

1. ANS:
The nitrogen atom in ephedrine is secondary.

PTS: 1
2. ANS:
The nitrogen atom in amphetamine is primary.
PTS: 1
3. ANS:
The nitrogen in mepiquat chloride is a quaternary ammonium salt.
PTS: 1
4. ANS:
The nitrogen atom in fexofenadine is tertiary
PTS: 1
5. ANS:

PTS: 1
6. ANS:

PTS: 1
7. ANS:
H2NCH2CH2CH2CH2NH2
PTS: 1
8. ANS:
N-isopropyll-N-methylcyclobutylamine
PTS: 1
9. ANS:

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


2,4-hexanediamine

PTS: 1
10. ANS:
methyl 2-aminobutanoate
PTS: 1
11. ANS:
N-ethylaniline
PTS: 1
12. ANS:
p-nitroaniline
PTS: 1
13. ANS:
The nucleophile is methylamine.
PTS: 1
14. ANS:
Dissolve the reaction mixture containing the ketone and amine in ether and extract with aqueous HCl. The
basic amine will dissolve in the aqueous layer as its hydrochloric salt. The neutral ketone will remain in the
ether layer. Separate the two layers and neutralize the aqueous layer with NaOH. Extract the neutralized layer
with ether. The purified amine will dissolve in the ether.
PTS: 1
15. ANS:
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.

PTS: 1
16. ANS:
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.

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


PTS: 1
17. ANS:

PTS: 1
18. ANS:
The reaction that is occurring is a carbonyl -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 -substitution product.
PTS: 1
19. ANS:

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


PTS: 1
20. ANS:
d
PTS: 1

21. ANS:

PTS: 1
22. ANS:

PTS: 1
23. ANS:

PTS: 1
24. ANS:

PTS: 1
25. ANS:

PTS: 1
26. ANS:

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


PTS: 1
27. ANS:

PTS: 1
28. ANS:

PTS: 1
29. ANS:

PTS: 1
30. ANS:

PTS: 1
31. ANS:

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


PTS: 1
32. ANS:

PTS: 1
33. ANS:

PTS: 1
34. ANS:

16

CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


PTS: 1
35. ANS:

PTS: 1

36. ANS:

PTS: 1
37. ANS:

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


PTS: 1
38. ANS:
c
PTS: 1
39. ANS:

PTS: 1
40. ANS:

PTS: 1
41. ANS:

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W


PTS: 1
42. ANS:

PTS: 1
43. ANS:
N,N-dimethylbutylamine
PTS: 1
44. ANS:

PTS: 1
45. ANS:

PTS: 1

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CHEM 2425. Chapter 24. Amines and Heterocycles (homework) W