Exam - UAlgw3.ualg.pt/~abrigas/w_amin.pdf · Exam Name ... MULTIPLE CHOICE. ... When pyrrole undergoes electrophilic aromatic substitution, at which position does substitution occur?

Exam

Name___________________________________

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

1) Draw the structure of N-ethyl-N-methyl-1-hexanamine. 1)

ESSAY. Write your answer in the space provided or on a separate sheet of paper.

2) Draw the structure of 2,3-dimethyl-2-butanamine

3) Draw the structure of piperidine.

4) Draw the structure of 3-pentanamine.

5) Draw the structure of N-propyl-4-methyl-3-octanamine.

6) Provide the systematic name for the compound below.

(CH3)4N+Cl-

7) Provide the name for the compound below.



MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

10) Which of the following is a tertiary amine?

A) N-ethyl-1-propanamine

B) 3-pentanamine

C) cyclohexylamine

D) N,N-dimethylaniline

E) methylamine

10)

1

11) Which of the following is a secondary amine?

A) 3-pentanamine

B) N-ethyl-1-propanamine

C) methylamine

D) N,N-dimethylaniline

E) cyclohexylamine

11)

12) Which of the following amines can be resolved into enantiomers?

A) trimethylamine

B) 3-pentanamine

C) 4-(dimethylamino) pyridine

D) 2-pentanamine

E) dimethylammonium chloride

12)


13) Why can't N-methyl-2-propanamine be resolved into isolable enantiomers even though the compound is

chiral?


14) Which of the following amines is most soluble in water?

A) (CH3)3N

B) pyrrolidine

C) ethylamine

D) (CH3CH2CH2)2NH

E) PhNH2

14)


15) Which has the higher boiling point, butan-1-ol or 1-butanamine? Explain briefly.

16) Rank the following compounds in order of increasing boiling point (lowest to highest): triethylamine,

cyclohexylamine, di-n-propylamine.

17) How might one distinguish a sample of trimethylamine from a sample of n-propylamine using IR

spectroscopy?

18) How might one distinguish a sample of n-butylamine from a sample of diethylamine using IR spectroscopy?

19) How might the presence of an N-H functionally be indicated using NMR spectroscopy?

20) Since alkyl groups are electron donors, one might conclude that tertiary amines are much more basic than

primary amines. Actually, primary and tertiary amines show similar ranges of basicity. Offer an explanation.

21) Provide the product of the reaction shown below.

2

22) Circle the stronger base in the pair below, and briefly explain your choice.



25) A sample of cyclohexylamine is contaminated with considerable hydrocarbon impurity. How might the sample

be purified using a technique based on solubility differences?

26) Provide the structure of the major organic product in the reaction below.


28) Why are strongly acidic reagents inappropriate when attempting an electrophilic aromatic substitution with

aniline?


30) Pyridine does not undergo Friedel-Crafts reactions. Offer an explanation.

3


31) When pyrrole undergoes electrophilic aromatic substitution, at which position does substitution

occur?

A) 2-position B) 4-position C) 3-position

31)

32) Which of the following chloropyridines readily undergo nucleophilic substitution upon treatment

with NaCN?

A) 4-chloropyridine

B) 3-chloropyridine

C) 2-chloropyridine

D) both A and C

E) both A and B

32)


33) Can 2-methyl-2-butanamine be prepared in good yield from the reaction of ammonia with

2-bromo-2-methylbutane? Why or why not?

34) Can 1-hexanamine be prepared in good yield from the reaction of a 1:1 molar ratio of ammonia and

1-bromohexane? Why or why not?


36) Provide a detailed, stepwise mechanism for the reaction of acetyl chloride with n-propylamine.



4


39) The Hofmann elimination proceeds via a(n) __________ pathway.

A) SN2

B) E1

C) E2

D) SN1

E) none of the above

39)


40) Provide the structure of the major organic product in the reaction below. 40)




42) Heating a(n) __________ results in a Cope elimination.

A) imine

B) oxime

C) enamine

D) amine oxide

E) quaternary ammonium salt

42)



5




45) Secondary amines react with the nitrosonium ion to generate:

A) N-nitrosoamines

B) imines

C) oximes

D) anilines

E) diazonium salts

45)







6


51) Devise an efficient method for preparing 1-pentanamine from but-1-ene.

52) Devise an efficient method for preparing ethylisopropylamine from ethylamine.

53) Devise an efficient method for preparing cyclohexylamine from cyclohexylmethanol.

54) Devise an efficient method for preparing 3-bromotoluene from toluene.

55) Devise an efficient method for preparing 4-bromobenzonitrile from benzene.

56) Devise an efficient method for preparing p-nitrobenzoic acid from toluene.

57) Devise an efficient method for preparing 1,4-diaminobutane from cyclohexene.

58) Devise an efficient method for preparing 1-pentanamine from 1-chloropentane.

59) Devise an efficient method for preparing m-cresol from m-toluidine.

60) Devise an efficient method for preparing 2-phenylethanamine from 2-phenylethanol.


61) Which of the following is not an alkaloid?

A) mescaline

B) cocaine

C) nicotine

D) morphine

E) mesitylene

61)


62) Provide the structure of N-ethyl-1-butanamine. 62)


63) The nitrogen atom of trimethylamine is __________ hybridized which is reflected in the CNC bond

angle of __________.

A) sp3, 120° B) sp2, 108° C) sp2, 120° D) sp, 180° E) sp3, 108°

63)


64) Why can 1,2,2-trimethylaziridine be resolved into enantiomers while N-methyl-1-propanamine cannot?

7

65) What common names for 1,4-butanediamine and 1,5-pentanediamine are derived from their characteristic

pungent odors?


66) Which of the following amines is most basic?

A) N-ethylaniline

B) pyrrole

C) piperidine

D) aniline

E) N,N-diethylaniline

66)

67) In 1H NMR protons on the α-carbon of amines typically absorb between θ:

A) 1.0 and 2.0 ppm

B) 2.0 and 3.0 ppm

C) 3.0 and 4.0 ppm

D) 6.0 and 7.0 ppm

E) 9.0 and 10.0 ppm

67)

68) In the mass spectrum of dipropylamine, the base peak appears at m/z:

A) 101

B) 86

C) 58

D) 72

E) none of the above

68)

69) When pyridine is treated with a mixture of nitric and sulfuric acids, the major product is:

A) 3-aminopyridine

B) 3-nitropyridine

C) 4-aminopyridine

D) 2-nitropyridine

E) 4-nitropyridine

69)


70) Devise an efficient method for preparing fluorobenzene from benzene. 70)


71) Which of the following compounds is a 2° amine?

A) t-butylamine

B) N-butylpyridinium bromide

C) N-ethylaniline

D) N,N-diethylaniline

E) cyclohexylamine

71)


72) Provide the structure of 2,4-dimethylpyridine 72)

8

73) Provide the IUPAC name for the compound shown below. 73)

74) Arrange the following compounds in order of increasing boiling point:

CH3NHCH2CH3, CH3OCH2CH3, (CH3)3N, and CH3CH2CH2OH.

74)


75) Which of the following amines is the strongest base?

A) pyrrole

B) p-iodoaniline

C) cyclohexylamine

D) imidazole

E) piperidine

75)

76) The α-carbon atom bonded to the nitrogen of an alkylamine usually appears in what chemical shift

(δ) range?

A) 30-50 B) 180-220 C) 80-100 D) 5-20 E) 120-150

76)

77) When pentanal reacts with ethylamine under conditions of acid catalysis, the major organic

product is __________.

A) a ketone

B) a nitrile

C) a hydrazone

D) an oxime

E) an imine

77)

78) When CH3CH2CHO reacts with PhNHNH2 under conditions of acid catalysis, the major organic

product is __________.

A) an imine

B) an oxime

C) a nitrile

D) a hydrazone

E) a ketone

78)

79) When a 1° amine reacts with an alkyl sulfonyl chloride, the major organic product is __________.

A) a sulfonamide

B) a nitrile

C) a tosylhydrazone

D) a sulfoxide

E) an oxime

79)


80) Provide the formula for nitrous acid. 80)

9

81) Provide the IUPAC name of (CH3)3CCH2CH2NHCH2CH3. 81)


82) The nitrogen's lone pair in pyrrolidine is best described as occupying what type of orbital?

A) sp3 B) s C) sp2 D) p E) sp

82)


83) Arrange the following compounds in order of increasing boiling point: ethyl methyl ether,

1-propanol, N-methylethanamine, and 1-propanamine.

83)


84) Sec-Butylamine is the common name of what compound?

A) 2-butanamine

B) 1-butanamine

C) N-methyl-1-propanamine

D) N-ethylethanamine

E) N-methyl-2-propanamine

84)


85) Arrange the following in order of increasing basicity: aniline, p-nitroaniline, p-toluidine,

and p-methoxyaniline.

85)


86) A three-carbon, nitrogen-containing compound exhibits 3 13C NMR peaks (d 11.2, 27.3, and 44.9).

Which of the following compounds best matches this spectral data?

A) CH3NHCH2CH3

B) H2NCH2CH2CH2OH

C) CH3CH2C≡N

D) (CH3)2CHNH2

E) CH3CH2CH2NH2

86)

87) Pyridine typically undergoes electrophilic aromatic substitution __________ rapidly than benzene,

and its preferred site of substitution is the __________ - position.

A) more, 3 B) more, 4 C) less, 3 D) more, 2 E) less, 2

87)


88) Provide the major organic compound in the following reaction. 88)

10




91) Which of the following compounds containing a tertiary amine?

1) 2-methyl-2-propanamine

2) N-ethylpyrrolidine

3) N-methylcyclohexylamine

4) 2-(dimethylamino)butanal

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

91)

92) Provide the correct IUPAC name for the following amine.

A) 4,N-dimethyl-4-penten-2-amine B) 1,3,N-trimethyl-3-buten-1-amine

C) 2,N-dimethyl-1-penten-4-amine D) 4-(methylamino)-2-methyl-1-pentene

92)


93) Circle all of the following structures that can be resolved into pure enantiomers. 93)


94) Which compound would react most rapidly with sodium methoxide and heat?

A) 2-chloropyridine B) chlorobenzene

C) 3-chloropyrrole D) 3-chloropyridine

94)

11

95) Which of the following is an intermediate in the mechanism for amide synthesis through acylation

of an amine?

A) B) C) D)

95)


96) Complete the short synthesis below by providing the necessary reagents. 96)


97) Which of the following amines could be formed by reduction of an amide?

1) benzylamine 2) isopropylamine 3) aniline 4) triethylamine

A) 2 and 3 B) 3 and 4 C) 1 and 4 D) 1, 3 and 4 E) 1

97)

98) Physostigmine is used in the treatment of glaucoma. Within this structure, the atom indicated by

__________ is most basic, while atom __________ is least basic.

A) 1 (most basic), 4 (least basic)

B) 2 (most basic), 3 (least basic)

C) 1 (most basic), 3 (least basic)

D) 2 (most basic), 4 (least basic)

E) None of the above

98)

12

Answer KeyTestname: W_AMIN

1)

2)

3)

4)

5)

6) tetramethylammonium chloride

7) pyrrole

8) 4-aminocyclohexanone

9) 2-bromo-N-methylaniline

10) D

11) B

12) D

13) Enantiomers interconvert rapidly via nitrogen inversion.

14) C

15) The O-H bond is more polar than the N-H because oxygen is more electronegative than nitrogen. Thus, alcohols form

stronger hydrogen-bonds and have higher boiling points.

16) triethylamine < di-n-propylamine < cyclohexylamine

17) n-Propylamine would show N-H stretches in the IR between 3200 and 3500 cm-1.

18) Primary amines, like n-butylamine, usually show two spikes in the N-H stretching region of the IR between 3200 and

3500 cm-1 while secondary amines usually show only one.

19) Like the O-H group, the N-H group undergoes a rapid H exchange reaction with water. Adding D2O to the NMR

sample would result in the disappearance of any peaks in the 1H NMR spectrum arising from N-H groups.

20) While tertiary ammonium cations are stabilized to a greater degree by electron donation, they are larger and thus more

poorly solvated.

21)

13


22) Pyrrolidine is the stronger base. Protonation of pyrrole results in loss of aromaticity.

23) Diethylamine is the stronger base. The lone pair electrons in pyridine are in an sp2 orbital which is lower in energy

than the sp3 orbital of the lone pair in diethylamine.

24) Cyclohexylamine is the stronger base. The lone pair electrons in aniline are delocalized into the adjacent aromatic π

system.

25) Dissolve sample in ether. Wash with dilute HCl solution to convert the amine to the ammonium hydrochloride which

is water soluble; hydrocarbon remains in ether. Neutralize the aqueous solution with base to reform the amine and

extract with ether.

26)

27)

28) Acidic reagents protonate the amino group transforming it from an activating group to a deactivating group.

29)

30) The presence of the electronegative atom in the ring deactivates it toward reaction with electrophiles. In fact, the

nitrogen lone pair tends to react with electropiles to produce an even further deactivated ring. It should also be noted

that the nitrogen lone pair is in an orbital perpendicular to the ring's π system and could not stabilize the intermediate

carbocation in any event.

31) A

32) D

33) No. SN2 reactions do not proceed with tertiary substrates.

34) No. Problems with multiple alkylation exist.

35)

14


36)

37)

38)

39) C

40)

41)

42) D

43)

44)

45) A

15


46)

47)

48)

49)

50)

51) 1. HBr, ROOR

2. NaCN

3. LiAlH4

52) CH3COCH3, NaBH3CN

53) 1. Na2Cr2O7, H2SO4

2. SOCl2

3. NH3

4. Br2, NaOH

54) 1. HNO3, H2SO4

2. Sn, HCl

3. CH3COCl

4. Br2, FeBr3

5. H3O+

6. H2SO4, NaNO2

7. H3PO2

55) 1. Br2, FeBr3

2. HNO3, H2SO4

3. Sn, HCl

4. H2SO4, NaNO2

5. CuCN

16


56) 1. HNO3, H2SO4

2. Na2Cr2O7, H2SO4

57) 1. KMnO4

2. SOCl2

3. NH3

4. Br2, NaOH

58) 1. phthalimide anion

2. H2NNH2, heat

or

1. NaN3

2. LiAlH4 or H2, Pd

59) 1. NaNO2, HCl

2. H3O+

60) 1. PCC

2. H2NOH

3. H2, Ni or LiAlH4

or

1. SOCl2

2. NaN3

3. LiAlH4 or H2, Pd

61) E

62) CH3CH2CH2CH2NHCH2CH3

63) E

64) In 1,2,2-trimethylaziridine the nitrogen atom is contained in a 3-membered ring and cannot readily achieve the sp2

transition state required for nitrogen inversion. Introduction of an sp2 center in a 3-membered ring greatly increases

the angle strain.

65) putrescine and cadaverine

66) C

67) B

68) D

69) B

70) 1. HNO3, H2SO4

2. Fe, HCl

3. -OH

4. NaNO2, HCl

5. HBF4

71) C

72)

73) 3,3-dimethyl-1-butanamine

17


74) (CH3)3N < CH3OCH2CH3 < CH3NHCH2CH3 < CH3CH2CH2OH

75) E

76) A

77) E

78) D

79) A

80) HNO2

81) N-ethyl-3,3-dimethyl-1-butanamine

82) A

83) ethyl methyl ether < N-methylethanamine < 1-propanamine < 1-propanol

84) A

85) p-nitroaniline < aniline < p-toluidine < p-methoxyaniline

86) E

87) C

88)

89)

90)

91) C

92) A

93)

94) A

18


95) A

96) 1) NaNO2 / HCl 2) CuCN 3) LiAlH4 or H2 / Pd

97) C

98) A

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Exam - UAlgw3.ualg.pt/~abrigas/w_amin.pdf · Exam Name ... MULTIPLE CHOICE. ... When pyrrole undergoes electrophilic aromatic substitution, at which position does substitution occur?