Test Bank For Organic Chemistry 8th Edition by Wade – Test Bank

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Test Bank For Organic Chemistry 8th Edition by Wade – Test Bank

 

Sample  Questions

 

 

 

Organic Chemistry, 8e (Wade)

Chapter 3   Structure and Stereochemistry of Alkanes

 

1) Which of the statements below accurately describe(s) alkanes?

  1. A) Alkanes are hydrocarbons which contain only single bonds.
  2. B) Alkanes belong to the class of unsaturated hydrocarbons.
  3. C) Alkanes are the simplest and least reactive class of organic compounds.
  4. D) both A and B
  5. E) both A and C

Answer:  E

Diff: 1

Section:  3.1

 

2) Which of the following types of hydrocarbons is(are) saturated?

  1. A) alkanes
  2. B) alkenes
  3. C) alkynes
  4. D) aromatics
  5. E) All of the above are saturated.

Answer:  A

Diff: 1

Section:  3.1

 

3) If a hydrocarbon has no double or triple bonds, it is said to be ________.

Answer:  saturated

Diff: 1

Section:  3.1

 

4) Straight-chain alkanes are also called ________.

Answer:  n-alkanes

Diff: 2

Section:  3.1

 

5) The structure below is a potent analgesic agent (pain reliever) (J. Med. Chem., 2009, 5685).  How many secondary carbons are in this structure?

 

 

 

  1. A) 2
  2. B) 4
  3. C) 6
  4. D) 12

Answer:  A

Diff: 2

Section:  3.1

 

6) If an acyclic alkane hydrocarbon contains n carbon atoms, how many hydrogen atoms must it also contain?

  1. A) n
  2. B) 2n
  3. C) n + 2
  4. D) 2n + 2
  5. E) n – 2

Answer:  D

Diff: 2

Section:  3.2

 

7) A series of compounds, like the n-alkanes, that differ only by the number of -CH2- groups, is called a(n) ________ series.

Answer:  homologous

Diff: 2

Section:  3.2

 

8) A bicyclic alkane contains 12 carbon atoms. How many hydrogen atoms does it contain?

  1. A) 20
  2. B) 22
  3. C) 24
  4. D) 26
  5. E) 28

Answer:  B

Diff: 2

Section:  3.2

 

9) How many methylene groups are present in 2,4-dimethylhexane?

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 6
  5. E) 8

Answer:  C

Diff: 2

Section:  3.2

 

10) Triacontane is an unbranched alkane that contains 30 carbon atoms in each molecule.  How many hydrogen atoms are present in each molecule of triacontane?

  1. A) 30
  2. B) 32
  3. C) 58
  4. D) 60
  5. E) 62

Answer:  E

Diff: 3

Section:  3.2

 

11) How many secondary (2°) carbons are found in 5-ethyl-3,3,4-trimethylheptane?

  1. A) 1
  2. B) 4
  3. C) 2
  4. D) 3
  5. E) 6

Answer:  D

Diff: 1

Section:  3.3

 

12) Provide an acceptable name for (CH3CH2CH2)3CH.

Answer:  4-propylheptane

Diff: 1

Section:  3.3

 

13) Provide the name of the compound below.

 

Answer:  3-fluoro-2,2-dimethylhexane

Diff: 1

Section:  3.3

 

14) Provide the name of the compound below.

 

Answer:  2,3,6,7-tetramethylnonane

Diff: 1

Section:  3.3

 

15) Provide an acceptable name for the alkane shown below.

 

CH3CH2CH2CH2CH2CH3

Answer:  hexane   or   n-hexane

Diff: 1

Section:  3.3

 

16) Provide an acceptable name for the alkane shown below.

 

Answer:  2,5-dimethylheptane

Diff: 1

Section:  3.3

 

17) Draw an acceptable structure for 4-tert-butyloctane.

Answer:

Diff: 1

Section:  3.3

 

18) Draw an acceptable structure for 3-ethyl-3-methylhexane.

Answer:

Diff: 1

Section:  3.3

 

19) Draw an acceptable structure for 4-isopropyl-2-methylheptane.

Answer:

Diff: 1

Section:  3.3

 

20) Name the haloalkane shown.

 

 

Answer:  3,4-dibromoheptane

Diff: 1

Section:  3.3

 

21) Provide an acceptable name for the following compound.

 

Answer:  4,4-dichloro-6-isopropyl-3-methylnonane

Diff: 2

Section:  3.3

 

22) Provide an acceptable name for the [(CH3)3C]2CHCH3.

Answer:  2,2,3,4,4-pentamethylpentane

Diff: 2

Section:  3.3

 

23) Provide the IUPAC name of (CH3CH2)3CH.

Answer:  3-ethylpentane

Diff: 2

Section:  3.3

 

24) Provide the IUPAC name of (CH3)2CHCH2CH2C(CH3)3.

Answer:  2,2,5-trimethylhexane

Diff: 2

Section:  3.3

 

25) Predict the molecular formula of 4-ethyl-5,5-dimethyldodecane.

Answer:  C16H34

Diff: 2

Section:  3.3

 

26) Provide an acceptable name for the alkane shown below.

 

Answer:  5-sec-butyl-2,2-dimethylnonane  or  2,2-dimethyl-5-(1-methylpropyl)nonane

Diff: 2

Section:  3.3

 

27) Provide an acceptable name for the alkane shown below.

 

Answer:  4-isopropyldecane   or   4-(1-methylethyl)decane

Diff: 2

Section:  3.3

 

28) Provide an acceptable name for the alkane shown below.

 

Answer:  3-ethyl-4,4-dimethylheptane

Diff: 2

Section:  3.3

 

29) Draw an acceptable structure for 6-ethyl-2,6,7-trimethyl-5-propylnonane.

Answer:

Diff: 2

Section:  3.3

 

30) Provide an acceptable name for the alkane shown below.

 

Answer:  2,2,3,6-tetramethylheptane

Diff: 2

Section:  3.3

 

31) Provide an acceptable name for the alkane shown below.

 

Answer:  6-ethyl-2-methyl-5-propyldecane

Diff: 2

Section:  3.3

 

32) Provide an acceptable name for the alkane shown below.

 

Answer:  5-ethyl-2,2-dimethylheptane

Diff: 2

Section:  3.3

 

33) Identify the correct IUPAC name for the following structures.

 

 

  1. A) 4-(2-iodo-1-methylethyl)-3-methylheptane
  2. B) 3-s-butyl-1-iodo-2-methylhexane
  3. C) 1-iodo-2,4-dimethyl-3-propylhexane
  4. D) 2,4-dimethyl-1-iodo-3-propylhexane

Answer:  A

Diff: 2

Section:  3.3

 

34) Name the haloalkane shown.

 

CH3CH2C(CH3)2CH2CH2I

Answer:  1-iodo-3,3-dimethylpentane

Diff: 2

Section:  3.3

 

35) Name the alkane shown.

 

[(CH3)2CH]2CHCH3

Answer:  2,3,4-trimethylpentane

Diff: 2

Section:  3.3

 

36) Name the alkane shown.

 

 

Answer:  5-ethyl-2,2-dimethyloctane

Diff: 2

Section:  3.3

 

37) How many methyl groups are present in 2,4-dimetylhexane?

  1. A) 0
  2. B) 2
  3. C) 4
  4. D) 6
  5. E) 8

Answer:  C

Diff: 2

Section:  3.3

 

38) Identify the correct IUPAC name for the following structure.

 

 

  1. A) 6-bromo-1-cyclopentyl-3,6-dimethylhexane
  2. B) 1-bromo-5-cyclopentyl-1,4-dimethylpentane
  3. C) 2-bromo-6-cyclopentyl-5-methylhexane
  4. D) 5-bromo-1-cyclopentyl-2-methylhexane
  5. E) none of the above

Answer:  D

Diff: 3

Section:  3.3

 

39) Identify the correct IUPAC name for each compound shown below.

 

 

  1. A) 2-bromo-3-sec-butyl-4-ethylhexane
  2. B) 2-bromo-4-ethyl-3-sec-butylhexane
  3. C) 3-(1-bromoethyl)-2,4-diethylhexane
  4. D) 4-(1-bromoethyl)-3-ethyl-5-methylheptane
  5. E) 4-(1-bromoethyl)-5-ethyl-3-methylheptane

Answer:  D

Diff: 3

Section:  3.3

 

40) Provide the name of the compound shown.

 

Answer:  2,2,7-trichloro-4-ethyl-6-isobutyl-7,10-dimethyldodecane

Diff: 3

Section:  3.3

 

41) Give structures for the three isomers with molecular formula C5H12 and provide the common name of each.

Answer:

Diff: 3

Section:  3.3

 

42) Provide an acceptable name for the alkane shown below.

 

Answer:  3-ethyl-7-methyl-5-propylnonane

Diff: 3

Section:  3.3

 

43) Draw an acceptable structure for 4-ethyl-6-(1,2-dimethylpropyl)decane.

Answer:

Diff: 3

Section:  3.3

 

44) Draw an acceptable structure for 1-ethyl-2-(2,2-dimethylpentyl)cyclopentane.

Answer:

Diff: 3

Section:  3.3

 

45) When one compares the densities of n-hexane and water, one finds:

  1. A) that n-hexane is less dense than water.
  2. B) that n-hexane is more dense than water.
  3. C) that these two compounds have the same density.
  4. D) that the relative densities of two immiscible compounds cannot be measured.

Answer:  A

Diff: 1

Section:  3.4

 

46) A branched alkane has ________ boiling point relative to the isomeric linear alkane.  There are ________ London force interactions in the branched alkane

  1. A) a higher; stronger
  2. B) a higher; weaker
  3. C) a lower, stronger
  4. D) a lower; weaker
  5. E) the same; similar

Answer:  D

Diff: 1

Section:  3.4

 

47) Consider the three isomeric alkanes n-hexane, 2,3-dimethylbutane, and 2-methylpentane. Which of the following correctly lists these compounds in order of increasing boiling point?

  1. A) 2,3-dimethylbutane < 2-methylpentane < n-hexane
  2. B) 2-methylpentane < n-hexane < 2,3-dimethylbutane
  3. C) 2-methylpentane < 2,3-dimethylbutane < n-hexane
  4. D) n-hexane < 2-methylpentane < 2,3-dimethylbutane
  5. E) n-hexane < 2,3-dimethylbutane < 2-methylpentane

Answer:  A

Diff: 2

Section:  3.4

 

48) A branched alkane generally melts at a ________ temperature than the n-alkane containing the same number of carbons.

Answer:  lower

Diff: 2

Section:  3.4

 

49) ________ is the n-alkane of greatest molecular weight which is a gas at room temperature and pressure.

Answer:  Butane

Diff: 2

Section:  3.4

 

50) Place the following alkanes in order of increasing boiling point:

 

CH3(CH2)6CH3, CH3(CH2)5CH3, (CH3)3CCH2CH2CH3

 

Answer:   (CH3)3CCH2CH2CH3 <  CH3(CH2)5CH3  <  CH3(CH2)6CH3

Diff: 2

Section:  3.4

 

51) Why are alkanes described as hydrophobic?

Answer:  Alkanes are nonpolar and as such they do not dissolve to any appreciable extent in water.

Diff: 2

Section:  3.4

 

52) Which intermolecular force is primarily responsible for the interactions among alkane molecules?

Answer:  van der Waals   or   London forces

Diff: 2

Section:  3.4

 

53) What is the major constituent of natural gas?

  1. A) octane
  2. B) butane
  3. C) propane
  4. D) ethane
  5. E) methane

Answer:  E

Diff: 1

Section:  3.5

 

54) Within the context of commercial uses of alkanes, explain what “knocking” is.

Answer:  “Knocking” is the potentially damaging, premature explosive combustion of certain gasoline mixtures in a car’s engine.

Diff: 1

Section:  3.5

 

55) Natural gas is primarily composed of

  1. A) oxygen.
  2. B) carbon dioxide.
  3. C) methane.
  4. D) octane.
  5. E) ethanol.

Answer:  C

Diff: 1

Section:  3.5

 

56) Which alkanes have largely replaced Freons as propellants in aerosol cans?

  1. A) methane and ethane
  2. B) propane and butane
  3. C) pentane and hexane
  4. D) nonane and decane
  5. E) none of the above

Answer:  B

Diff: 2

Section:  3.5

 

57) How many carbons do the primary alkane constituents of gasoline contain?

  1. A) C1C2
  2. B) C3C4
  3. C) C5C8
  4. D) C8C12
  5. E) C12C16

Answer:  C

Diff: 2

Section:  3.5

 

58) ________ is the reaction process through which long-chain alkanes are converted into a mixture of short-chain alkanes and alkenes.

Answer:  Catalytic cracking

Diff: 2

Section:  3.5

 

59) List three commercial products which are composed primarily of alkanes.

Answer:  natural gas, gasoline, kerosene, heating oil, lubricating oil, liquefied petroleum gas, jet fuel, diesel oil, petroleum jelly

Diff: 2

Section:  3.5

60) Name the two major steps in the refining of crude oil into usable hydrocarbon products.

Answer:  1. fractional distillation

  1. cracking (catalytic cracking and/or hydrocracking)

Diff: 2

Section:  3.5

 

61) In the complete combustion of heptane, how many moles of water are produced?

Answer:  8

Diff: 2

Section:  3.6

 

62) By using the appropriate molecular formulas, write a balanced equation which describes the complete combustion of cyclohexane.

Answer:  C6H12  +  9 O2  →  6 CO2  +  6 H2O

Diff: 2

Section:  3.6

 

63) When a mole of decane undergoes complete combustion, how many moles of water are formed?

  1. A) 1
  2. B) 10
  3. C) 11
  4. D) 15.5
  5. E) 22

Answer:  C

Diff: 2

Section:  3.6

 

64) By using the appropriate molecular formulas, write a balanced equation which describes the complete combustion of nonane.

Answer:  CH3(CH2)7CH3  +  14 O2  →  9 CO2  +  10 H2O

Diff: 3

Section:  3.6

 

65) The energy barrier for carbon-carbon bond rotation in propane is mainly due to ________.

  1. A) angle strain
  2. B) bond strain
  3. C) muscle strain
  4. D) steric strain
  5. E) torsion strain

Answer:  E

Diff: 1

Section:  3.7

 

66) The structures below are:

  1. A) not isomers.
  2. B) conformational isomers.
  3. C) cis-trans isomers.
  4. D) structural isomers.
  5. E) both B and D

Answer:  D

Diff: 2

Section:  3.7

 

67) Which of the following best describes the molecules of a sample of ethane gas at room temperature?

  1. A) Almost all of the molecules are frozen or locked in the eclipsed conformation.
  2. B) Almost all of the molecules are frozen or locked in the staggered conformation.
  3. C) The molecules are rapidly interconverting between the eclipsed and staggered conformations, but at any one time slightly more of them are present in the eclipsed conformation.
  4. D) The molecules are rapidly interconverting between the eclipsed and staggered conformations, but at any one time slightly more of them are present in the staggered conformation.

Answer:  D

Diff: 2

Section:  3.7

 

68) Draw a Newman projection of the most stable conformation of 2-methylpropane.

Answer:

Diff: 2

Section:  3.7

 

69) Define the term conformation.

Answer:  Conformations are different arrangements of the same molecule formed by rotations about single bonds.

Diff: 2

Section:  3.7

 

70) Use a sawhorse structure to depict the eclipsed conformer of ethane.

Answer:

Diff: 2

Section:  3.7

 

71) Draw the Newman projection of the highest energy conformation that results from rotation about the C2-C3 bond of 2,2-dimethylbutane.

Answer:

Diff: 1

Section:  3.8

 

72) Which of the following statements concerning the conformers of butane is true?

  1. A) Unlike ethane, all butane conformers are classified as eclipsed.
  2. B) The lowest energy conformer of butane is the gauche conformer.
  3. C) There is more torsional strain in the anti conformer than in the totally eclipsed conformer.
  4. D) The eclipsed and totally eclipsed conformers have the same amount of nonbonded strain.
  5. E) The gauche and anti conformers differ primarily in the amount of nonbonded strain present.

Answer:  E

Diff: 2

Section:  3.8

 

73) Draw the Newman projection of the lowest energy conformation that results from rotation about the C2-C3 bond of 2-methylbutane.

Answer:

Diff: 2

Section:  3.8

 

74) Draw the Newman projection of the lowest energy conformation that results from rotation about the C2-C3 bond of 2,2-dimethylbutane.

Answer:

Diff: 2

Section:  3.8

 

75) Draw the Newman projection of the highest energy conformation that results from rotation about the C2-C3 bond of 2-methylbutane.

Answer:

Diff: 2

Section:  3.8

 

76) Consider rotation about the C3-C4 bond of hexane, and draw the Newman projection for the most stable conformation.

Answer:

Diff: 2

Section:  3.8

 

77) Arrange the following conformers of butane in order of energy, lowest to highest: eclipsed, totally eclipsed, gauche, and anti.

Answer:  anti < gauche < eclipsed < totally eclipsed

Diff: 2

Section:  3.8

 

78) Among the butane conformers, which occur at energy minima on a graph of potential energy versus dihedral angle?

  1. A) gauche only
  2. B) eclipsed and totally eclipsed
  3. C) gauche and anti
  4. D) eclipsed only
  5. E) anti only

Answer:  C

Diff: 3

Section:  3.8

 

79) For the compound represented by the Newman projection below, what is the dihedral angle between the methyl groups in the conformer that has the smallest molecular dipole moment?

 

  1. A) 0°
  2. B) 30°
  3. C) 60°
  4. D) 120°
  5. E) 180°

Answer:  C

Diff: 3

Section:  3.8

 

80) Without any change in conformation, translate the Newman projection shown below to a perspective structure.

 

Answer:

Diff: 3

Section:  3.8

 

81) View a butane molecule along the C2C3 bond and provide a Newman projection of the lowest energy conformer.

Answer:

Diff: 3

Section:  3.8

 

82) Provide a representation of the gauche conformer of butane.

Answer:

Diff: 3

Section:  3.8

 

83) From the perspective of viewing down the C2C3 bond, draw the Newman projection of the most stable conformation of 2,3-dimethylbutane.

Answer:

Diff: 3

Section:  3.8

 

84) From the perspective of viewing down the C2-C3 bond, draw the Newman projection of the least stable conformation of 2,3-dimethylbutane.

Answer:

Diff: 3

Section:  3.8

 

85) In a Newman projection, siting down the C3-C4 bond, draw the structure below in its most stable conformation.

 

 

 

Answer:

 

Diff: 3

Section:  3.9

 

86) If a monocyclic alkane hydrocarbon contains n carbon atoms, how many hydrogen atoms must it also contain?

  1. A) n
  2. B) 2n
  3. C) n + 2
  4. D) 2n + 2
  5. E) n – 2

Answer:  B

Diff: 1

Section:  3.10

 

87) Give the IUPAC name for the cycloalkane shown below.

 

Answer:  trans-1-ethyl-2-methylcyclopentane

Diff: 1

Section:  3.10

88) Give the IUPAC name for the cycloalkane shown below.

 

Answer:  cis-1-isopropyl-3-methylcycloheptane

Diff: 1

Section:  3.10

 

 

89) What element of ring strain exists in cyclooctane but not in cyclopropane?

 

Answer:  transannular strain

Diff: 1

Section:  3.10

 

90) Provide an acceptable name for the following compound.

 

Answer:  isobutylcyclopentane  or  (2-methylpropyl)cyclopentane

Diff: 2

Section:  3.10

 

91) Provide the name of the compound below.

 

Answer:  sec-butylcycloheptane

Diff: 2

Section:  3.10

92) Identify the correct IUPAC name for the structure shown below.

 

  1. A) 1-tert-butyl-2-chloro-5-bromocycloheptane
  2. B) 5-bromo-1-tert-butyl-2-chlorocycloheptane
  3. C) 1-bromo-4-chloro-5-tertbutylcycloheptane
  4. D) 1-bromo-4-tert-butyl-5-chlorocycloheptane
  5. E) 1-tert-butyl-4-bromo-7-chlorocycloheptane

Answer:  B

Diff: 3

Section:  3.10

 

 

93) Given the following heats of combustion per CH2 group within the structure, which cyclic alkane has essentially no angle strain?  (Ref: long-chain Alkane = 659 kJ/mol)

  1. A) cyclobutane = 686 kJ/mol
  2. B) cyclopentane = 664 kJ/mol
  3. C) cyclohexane = 659 kJ/mol
  4. D) cycloheptane = 662 kJ/mol
  5. E) cyclooctane = 663 kJ/mol

Answer:  C

Diff: 1

Section:  3.12

 

94) Which of the following cycloalkanes exhibits the greatest molar heat of combustion?

  1. A) cyclooctane
  2. B) cycloheptane
  3. C) cyclohexane
  4. D) cyclobutane
  5. E) cyclopropane

Answer:  A

Diff: 2

Section:  3.12

 

95) Which of the following correctly ranks the cycloalkanes in order of increasing ring strain per methylene?

  1. A) cyclopropane < cyclobutane < cyclohexane < cyclopentane
  2. B) cyclohexane < cyclopentane < cyclobutane < cyclopropane
  3. C) cyclohexane < cyclobutane < cyclopentane < cyclopropane
  4. D) cyclopentane < cyclopropane < cyclobutane < cyclohexane
  5. E) cyclopropane < cyclopentane < cyclobutane < cyclohexane

Answer:  B

Diff: 2

Section:  3.12

96) Which of the following cycloalkanes has the smallest heat of combustion per CH2 group?

  1. A) cyclopropane
  2. B) cyclobutane
  3. C) cyclopentane
  4. D) cyclohexane
  5. E) cycloheptane

Answer:  D

Diff: 2

Section:  3.12

 

 

97) Which of the following statements regarding cyclobutane is correct?

  1. A) The lowest energy conformation of cyclobutane is a planar one in which all of the bond angles is 90°.
  2. B) The lowest energy conformation of cyclobutane is known as the chair conformation.
  3. C) The lowest energy conformation is one in which the bond angles are slightly less than 90° even though this increases angle strain.
  4. D) The lowest energy conformation is one in which the bond angles are greater than 90° so that angle strain is significantly reduced.
  5. E) None of the above statements is correct.

Answer:  C

Diff: 3

Section:  3.12

 

98) Which has the greatest molar heat of combustion?

  1. A) trans-1,2-dimethylcyclopentane
  2. B) cis-1,2-dimethylcyclopentane
  3. C) trans-1,3-dimethylcyclopentane
  4. D) methylcyclohexane
  5. E) cycloheptane

Answer:  B

Diff: 3

Section:  3.12

 

99) Describe the sources of angle strain and torsional strain present in cyclopropane.

Answer:  The angle strain arises from the compression of the ideal tetrahedral bond angle of 109.5° to 60°. The large torsional strain occurs since all CH bonds on adjacent carbons are eclipsed.

Diff: 3

Section:  3.12

100) The twisted boat conformation of cyclohexane is actually a slightly lower energy conformation than the boat conformation.  Which of the following accurately describes one factor involved in this structural behavior ?

  1. A) lower angle strain in the boat
  2. B) higher torsional strain in the twisted boat
  3. C) fewer unfavorable steric factors in the twisted boat
  4. D) increased rotational freedom in the boat
  5. E) lower bond strain in the boat

Answer:  C

Diff: 1

Section:  3.13

 

 

101) Draw the chair conformer of cyclohexane. Label the axial hydrogens (Ha) and the equatorial hydrogens (He).

Answer:

Diff: 1

Section:  3.13

 

102) In the boat conformation of cyclohexane, the “flagpole” hydrogens are located:

  1. A) on the same carbon.
  2. B) on adjacent carbons.
  3. C) on C-1 and C-3.
  4. D) on C-1 and C-4.
  5. E) none of the above

Answer:  D

Diff: 2

Section:  3.13

 

103) Which of the following correctly lists the conformations of cyclohexane in order of increasing energy?

  1. A) chair < boat < twist < half-chair
  2. B) half-chair < boat < twist < chair
  3. C) chair < twist < half-chair < boat
  4. D) chair < twist < boat < half-chair
  5. E) half-chair < twist < boat < chair

Answer:  D

Diff: 3

Section:  3.13

 

104) Consider the equilibrium shown below.  When one looks at the equilibrium where X = CH3 and the one where X = CH(CH3)2, how do the values of the equilibrium constants (Ks) compare?

 

 

  1. A) The Ks are equal.
  2. B) The K where X = CH3is greater.
  3. C) The K where X = CH(CH3)2is greater.
  4. D) The Ks differ only slightly and are both less than 1.

Answer:  C

Diff: 2

Section:  3.14

 

105) The energy difference between the axial and equatorial conformers of methylcyclohexane is:

  1. A) < 0.1 kcal/mol.
  2. B) 0.9 kcal/mol.
  3. C) 1.7 kcal/mol.
  4. D) 2.5 kcal/mol.
  5. E) > 5.0 kcal/mol.

Answer:  C

Diff: 3

Section:  3.14

 

106) In the lowest energy chair conformation of cis-1,3-dimethylcyclohexane, how many axial positions are occupied by hydrogen atoms?

  1. A) 2
  2. B) 3
  3. C) 4
  4. D) 5
  5. E) 6

Answer:  E

Diff: 1

Section:  3.15

107) Which of the following statements is a correct description of the most stable conformation of 1,1,3-trimethylcyclohexane?

  1. A) The methyl group at C-3 is equatorial.
  2. B) C-1 is a tertiary carbon and C-3 is a primary carbon.
  3. C) C-1 is a quaternary carbon and C-3 is a secondary carbon.
  4. D) C-1 is a tertiary carbon and C-3 is a secondary carbon.
  5. E) Both methyl groups at C-1 are equatorial.

Answer:  A

Diff: 2

Section:  3.15

 

108) Which of the statements below correctly describes the chair conformations of

  1. A) The two chair conformations are of equal energy.
  2. B) The higher energy chair conformation contains one axial methyl group and one equatorial methyl group.
  3. C) The lower energy chair conformation contains one axial methyl group and one equatorial methyl group.
  4. D) The higher energy chair conformation contains two axial methyl groups.
  5. E) The lower energy chair conformation contains two axial methyl groups.

Answer:  D

Diff: 2

Section:  3.15

 

109) Which of the statements below correctly describes the chair conformations of

  1. A) The two chair conformations are equal in energy.
  2. B) The higher energy chair conformation contains two axial ethyl groups.
  3. C) The higher energy chair conformation contains two equatorial ethyl groups.
  4. D) The lower energy chair conformation contains two axial ethyl groups.
  5. E) The lower energy chair conformation contains two equatorial ethyl groups.

Answer:  A

Diff: 2

Section:  3.15

110) In the lowest energy conformation of the compound below, how many alkyl substituents are equatorial?

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 6

Answer:  C

Diff: 2

Section:  3.15

 

 

111) In the lowest energy conformation of the compound below, how many alkyl substituents are axial?

 

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 6

Answer:  A

Diff: 2

Section:  3.15

 

112) Assuming a chair conformation, which of the following configurations will always have both methyl groups in relative axial/equatorial positions?

  1. A) trans-1,3-dimethylcyclohexane
  2. B) cis-1,3-dimethylcyclohexane
  3. C) cis-1,2-dimethylcyclohexane
  4. D) trans-1,2-dimethylcyclohexane
  5. E) Both B and D are correct.
  6. F) Both A and C are correct.

Answer:  F

Diff: 2

Section:  3.15

113) Draw the most stable conformation of cis-1-t-butyl-4-methylcyclohexane.

Answer:

Diff: 2

Section:  3.15

 

 

114) Draw the chair conformation of the cyclohexane derivative shown.

 

Answer:

Diff: 2

Section:  3.15

 

115) Draw the most stable conformation of cis-1,4-dipropylcyclohexane.

Answer:

Diff: 2

Section:  3.15

 

116) Draw the most stable conformation of trans-1,4-dipropylcyclohexane.

Answer:

Diff: 2

Section:  3.15

 

117) Draw the most stable conformation of trans-1,2-dimethylcyclohexane.

Answer:

Diff: 2

Section:  3.15

118) Draw the most stable conformation of cis-1,2-dimethylcyclohexane.

Answer:

Diff: 2

Section:  3.15

 

 

119) Draw the most stable conformation of trans-1-tert-butyl-3-ethylcyclohexane.

Answer:

Diff: 2

Section:  3.15

 

120) Draw the most stable conformation of cis-1-ethyl-3-methylcyclohexane.

Answer:

Diff: 2

Section:  3.15

 

121) Draw the most stable conformation of cis-1-ethyl-4-isopropylcyclohexane.

Answer:

Diff: 2

Section:  3.15

 

122) Which of the following difluorocyclohexane isomers has the greatest molecular dipole in its least stable chair conformation?

  1. A) cis 1,2-difluorocyclohexane
  2. B) trans 1,2-difluorocyclohexane
  3. C) cis 1,3-difluorocyclohexane
  4. D) trans 1,3-difluorocyclohexane

Answer:  C

Diff: 3

Section:  3.15

123) Which of the following correctly lists the conformations of cis-1,4-di-t-butylcylcohexane in order of increasing energy?

  1. A) chair < boat < twist boat < half-chair
  2. B) twist boat < boat < chair < half-chair
  3. C) chair < twist boat < half-chair < boat
  4. D) boat < chair < twisted boat < half-chair
  5. E) half-chair < chair < boat < twisted boat

Answer:  B

Diff: 3

Section:  3.15

 

 

124) With each structure below drawn in its most stable chair conformation, identify the

sequence that ranks the structures in order of increasing stability.

 

 

  1. A) 1 < 2 < 3
  2. B) 2 < 3 < 1
  3. C) 3 < 1 < 2
  4. D) 2 < 1 < 3

Answer:  D

Diff: 3

Section:  3.15

 

125) Circle all substituents that would be expected to occupy an axial position in the fused bicyclic structure below.

 

 

 

Answer:

 

Diff: 3

Section:  3.15

126) Which of the following is a bridged bicyclic alkane?

  1. A) cis-decalin
  2. B) bicyclo[2.2.1]heptane
  3. C) bicyclo[3.2.0]heptane
  4. D) bicyclo[4.1.0]heptane
  5. E) none of the above

Answer:  B

Diff: 2

Section:  3.16

 

 

127) Which of the following describes the compound below?

  1. A) bridged bicyclic
  2. B) fused bicyclic
  3. C) spiro bicyclic
  4. D) bridged tricyclic

Answer:  A

Diff: 2

Section:  3.16

 

128) Provide an acceptable name for the compound below.

 

Answer:  bicyclo[2.1.1]hexane

Diff: 2

Section:  3.16

 

129) Provide an acceptable structure for spiro [4.4]nonane.

Answer:

Diff: 3

Section:  3.16

130) Draw the most stable conformation of trans-decalin.

Answer:

Diff: 3

Section:  3.16

Organic Chemistry, 8e (Wade)

Chapter 5   Stereochemistry

 

1) ________ are isomers which have the same bonding sequence but differ in the orientation of their atoms in space.

Answer:  Stereoisomers

Diff: 1

Section:  5.1

 

2) What term describes the structural relationship between cis-1,2-dimethylcyclopentane and trans-1,3-dimethylcyclopentane?

  1. A) not isomers
  2. B) constitutional isomers
  3. C) enantiomers
  4. D) diastereomers
  5. E) conformers

Answer:  B

Diff: 2

Section:  5.1

 

3) What term describes the structural relationship between (2R,3R,4S)-2,3,4-trichloroheptane and (2S,3S,5R)-2,3,5-trichloroheptane?

  1. A) not isomers
  2. B) constitutional isomers
  3. C) enantiomers
  4. D) diastereomers
  5. E) conformers

Answer:  B

Diff: 2

Section:  5.1

4) What is the structural relationship between the two molecule shown below?

 

  1. A) constitutional isomers
  2. B) enantiomers
  3. C) diastereomers
  4. D) conformational isomers
  5. E) not isomers

Answer:  A

Diff: 2

Section:  5.1

 

5) How many enantiomers are there of the molecule shown below?

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 6

Answer:  B

Diff: 1

Section:  5.2

6) Which of the following incorrectly describes cis-1,2-dimethylcyclopentane?

  1. A) It is a meso compound.
  2. B) It is achiral.
  3. C) It contains two asymmetric carbons.
  4. D) Its diastereomer is trans-1,2-dimethylcyclopentane.
  5. E) It has an enantiomer.

Answer:  E

Diff: 1

Section:  5.2

 

7) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the same compound?

 

Answer:  the same compound

Diff: 1

Section:  5.2

 

 

8) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the same compound?

 

Answer:  the same compound

Diff: 1

Section:  5.2

 

9) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the same compound?

 

Answer:  enantiomers

Diff: 1

Section:  5.2

10) Is the molecule shown below chiral or achiral?

 

(CH3)3CCH(CH3)2

Answer:  achiral

Diff: 1

Section:  5.2

 

11) How many asymmetric carbon atoms are present in the following compound?

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 4

Answer:  B

Diff: 1

Section:  5.2

 

 

12) How many asymmetric carbon atoms are present in the following compound?

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 4

Answer:  A

Diff: 1

Section:  5.2

13) How many asymmetric carbons are present in the compound below?

 

Answer:  1

Diff: 1

Section:  5.2

 

14) How many asymmetric carbons are present in the compound below?

 

Answer:  none

Diff: 1

Section:  5.2

 

15) How many asymmetric carbons are present in the compound below?

 

Answer:  5

Diff: 1

Section:  5.2

 

16) How many asymmetric carbon atoms are present in the molecule shown?

 

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 4

Answer:  A

Diff: 1

Section:  5.2

17) How many asymmetric carbon atoms are present in the molecule shown?

 

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 4

Answer:  A

Diff: 1

Section:  5.2

 

18) How many asymmetric carbon atoms are present in the molecule shown?

 

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 4

Answer:  B

Diff: 1

Section:  5.2

 

 

19) How many asymmetric carbon atoms are present in the molecule shown?

 

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 4

Answer:  C

Diff: 1

Section:  5.2

20) What term describes the structural relationship between (2R,3R,4S)-2,3,4-trichloroheptane and (2S,3S,4R)-2,3,4-trichloroheptane?

  1. A) not isomers
  2. B) constitutional isomers
  3. C) enantiomers
  4. D) diastereomers
  5. E) conformers

Answer:  C

Diff: 2

Section:  5.2

 

21) If possible, draw the structure of the enantiomer of the molecule shown below.

 

Answer:

Diff: 2

Section:  5.2

 

 

22) Is the mirror image of the following molecule an enantiomer or is it superimposable with it?

 

Answer:  Superimposable.  The molecule is achiral.

Diff: 2

Section:  5.2

23) Draw the enantiomer of the molecule shown below.

 

Answer:

Diff: 2

Section:  5.2

 

24) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the same compound?

 

Answer:  enantiomers

Diff: 2

Section:  5.2

 

 

25) Which of the statements below correctly describes an achiral molecule?

  1. A) The molecule has a nonsuperimposable mirror image.
  2. B) The molecule exhibits optical activity when it interacts with plane-polarized light.
  3. C) The molecule has an enantiomer.
  4. D) The molecule might be a meso form.
  5. E) None of the above

Answer:  D

Diff: 2

Section:  5.2

26) Circle each chiral molecule among those shown below.

 

 

 

Answer:

Diff: 2

Section:  5.2

 

27) Circle each chiral molecule among those shown below.

 

 

 

Answer:

Diff: 2

Section:  5.2

 

 

28) Is the molecule shown below chiral or achiral?

 

CH3CH2CH(CH3)CH2CH3

Answer:  achiral

Diff: 2

Section:  5.2

29) Is the molecule shown below chiral or achiral?

 

Answer:  achiral

Diff: 2

Section:  5.2

 

30) Is the molecule shown below chiral or achiral?

 

Answer:  chiral

Diff: 2

Section:  5.2

 

31) Is the molecule shown below chiral or achiral?

 

Answer:  achiral

Diff: 2

Section:  5.2

 

32) Is the molecule shown below chiral or achiral?

 

Answer:  achiral

Diff: 2

Section:  5.2

 

33) Is the molecule shown below chiral or achiral?

 

Answer:  chiral

Diff: 2

Section:  5.2

 

34) How many asymmetric carbons are present in the compound below?

 

Answer:  2

Diff: 2

Section:  5.2

 

35) How many asymmetric carbons are present in the compound below?

 

3-ethyl-2,2,4-trimethylpentane

Answer:  1

Diff: 2

Section:  5.2

 

36) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the same compound?

 

Answer:  enantiomers

Diff: 3

Section:  5.2

 

37) Circle all structures shown below that are chiral.

 

 

 

Answer:

Diff: 3

Section:  5.2

 

38) Is the molecule shown below chiral or achiral?

 

Answer:  achiral

Diff: 3

Section:  5.2

 

39) Is the molecule shown below chiral or achiral?

 

Answer:  achiral

Diff: 3

Section:  5.2

 

40) Is the molecule shown below chiral or achiral?

 

Answer:  achiral

Diff: 3

Section:  5.2

 

41) Which of the following structures are achiral and meso?

 

 

  1. A) 1, 2, 3 & 4
  2. B) 1 &2
  3. C) 2 & 3
  4. D) 1 & 4

Answer:  D

Diff: 3

Section:  5.2

 

42) Does the molecule shown below contain asymmetric carbon atoms? Is this molecule chiral?

 

Answer:  Yes, the molecule contains 4 asymmetric carbon atoms. No, the molecule is not chiral since it is superimposable with its mirror image.

Diff: 3

Section:  5.2

 

43) How many asymmetric carbons are present in the compound below?

 

Answer:  5

Diff: 3

Section:  5.2

 

44) Label each asymmetric carbon in the compound below as R or S.

 

Answer:

Diff: 1

Section:  5.3

 

45) Draw the structure of (S)-1-bromo-1-chloropropane. Take particular care to indicate three-dimensional stereochemical detail properly.

Answer:

Diff: 1

Section:  5.3

 

46) Draw the Fischer projection of (S)-2-bromobutane.

Answer:

Diff: 1

Section:  5.3

 

47) Draw the structure of (2R,3R)-2,3-dibromo-3-chloropentane.

Answer:

Diff: 2

Section:  5.3

 

48) Label each asymmetric carbon in the molecule below as having the R or S configuration.

 

 

 

Answer:

Diff: 2

Section:  5.3

 

49) Assign the proper configurational label, R or S, to the chiral carbon in the molecule shown below.

 

Answer:  S

Diff: 2

Section:  5.3

 

50) Assign the proper configurational label, R or S, to each chiral carbon in the molecule below.

 

 

 

Answer:

Diff: 2

Section:  5.3

 

51) Label each asymmetric carbon in the compound below as R or S.

 

Answer:

Diff: 2

Section:  5.3

 

52) Label each asymmetric carbon in the compound below as R or S.

 

Answer:

Diff: 2

Section:  5.3

 

53) Draw the structure of (2R,3S)-2,3-dichloropentane. Take particular care to indicate three-dimensional stereochemical detail properly.

Answer:

Diff: 2

Section:  5.3

 

54) Draw the structure of the enantiomer of (2S, 3R)-2,3-dichloropentane. Take particular care to indicate three-dimensional stereochemical detail properly.

Answer:

Diff: 2

Section:  5.3

 

55) Draw the structure of any diastereomer of (2S, 3R)-2,3-dichloropentane. Take particular care to indicate three-dimensional stereochemical detail properly.

Answer:

Diff: 2

Section:  5.3

 

56) Draw the structure of (1R, 2R)-1-bromo-2-chlorocyclobutane. Take particular care to indicate stereochemistry properly.

Answer:

Diff: 2

Section:  5.3

 

57) Draw the structure of (S)-3-chloro-3-methylhexane. Take particular care to indicate stereochemistry properly.

Answer:

Diff: 2

Section:  5.3

 

58) Draw the structure of (1R, 2S, 3S)-1,2-dibromo-3-ethylcyclohexane. Take particular care to indicate stereochemistry properly.

Answer:

Diff: 2

Section:  5.3

 

59) Label each asymmetric carbon in the compound below as R or S.

 

 

 

 

Answer:

Diff: 2

Section:  5.3

 

60) Label each asymmetric carbon in the compound below as R or S.

 

 

 

Answer:

Diff: 2

Section:  5.3

 

61) Which of the following configurations corresponds to the structure below?

 

  1. A) (4R, 5R)
  2. B) (4R, 5S)
  3. C) (4S, 5R)
  4. D) (4S, 5S)

Answer:  A

Diff: 3

Section:  5.3

 

62) For the structure shown below, draw the stereoisomer having a configuration of (1R,3S,4S) in a perspective structure.

 

 

Answer:

 

Diff: 3

Section:  5.3

 

63) Captopril is used to treat high blood pressure and congestive heart failure.  Label the chiral centers as R or S.

 

Answer:

 

Diff: 3

Section:  5.3

 

64) Label each asymmetric carbon in the compound below as R or S.

 

Answer:

Diff: 3

Section:  5.3

 

65) Label each asymmetric carbon in the compound below as R or S.

 

Answer:

Diff: 3

Section:  5.3

 

66) Phantasmidine, shown below, is found in poisonous frog skin and has analgesic properties (J. Nat. Prod. 2010, 331).  Assign each chiral center as having either R or S configuration.

 

 

 

Answer:

Diff: 3

Section:  5.3

 

67) Compounds that rotate the plane of polarized light clockwise are called ________.

Answer:  dextrorotatory

Diff: 1

Section:  5.4

 

68) Which of the following statements is (are) true for the compound (R)-2-butanol?

  1. A) This compound is chiral.
  2. B) This compound is optically active.
  3. C) This compound has an enantiomer.
  4. D) all of the above
  5. E) none of the above

Answer:  D

Diff: 2

Section:  5.4

 

69) Which of the following statements correctly pertains to a pair of enantiomers?

  1. A) They rotate the plane of polarized light by exactly the same amount and in opposite directions.
  2. B) They rotate the plane of polarized light by differing amounts and in opposite directions.
  3. C) They rotate the plane of polarized light by differing amounts and in the same direction.
  4. D) The have different melting points.
  5. E) They have the same melting point, but they have different boiling points.

Answer:  A

Diff: 2

Section:  5.4

70) If (S)-glyceraldehyde has a specific rotation of -8.7°, what is the specific rotation of (R)-glyceraldehyde?

  1. A) 0.0°
  2. B) -8.7°
  3. C) +8.7°
  4. D) cannot be determined from the information given

Answer:  C

Diff: 2

Section:  5.4

 

71) Predict the specific rotation of the compound shown.

 

  1. A) It is impossible to predict; it must be determined experimentally.
  2. B) Because both asymmetric centers are R, the compound is dextrorotatory.
  3. C) Because both asymmetric centers are S, the compound is levorotatory.
  4. D) Zero; the compound is achiral.
  5. E) Because this compound represents a racemic mixture, the compound is dextrorotatory.

Answer:  D

Diff: 2

Section:  5.4

 

72) Would a 50:50 mixture of (2R,3R)-2,3-dibromobutane and (2R,3S)-2,3-dibromobutane be optically active?  Explain.

Answer:  Yes, the mixture would be optically active.  This is not a racemic mixture but a mixture of diastereomers.  The specific rotations of diastereomers are not the same in magnitude nor necessarily opposite in sign.

Diff: 2

Section:  5.4

 

73) Can one predict whether a compound with a single asymmetric carbon is dextro- or levorotatory based on the R/S assignment at this asymmetric carbon? Explain briefly.

Answer:  No. R/S assignment is purely a convention of nomenclature and is completely independent of the direction in which plane-polarized light is rotated by the compound.

Diff: 2

Section:  5.4

74) Given that glucose has a specific rotation of +52.8°.  Predict the concentration of a glucose aqueous solution contained in a 10 cm long polarimetry tube if a rotation of +15.8° was observed.

  1. A) 0.299 g/mL
  2. B) .0299 g/mL
  3. C) 3.34 g/mL
  4. D) .334 g/mL

Answer:  A

Diff: 2

Section:  5.4

 

 

75) A student measured the optical activity of an unknown sugar at two different concentrations.  The results of his measurements are shown below.  Given that the sample cell had a path length of 10.0 cm, calculate the specific rotation for the unknown sugar. (Hint: Consider each measurement of plane polarized light has a true reading and a “ghost” reading 180° from the true reading).

 

concentration                                   observed rotation

2.00 g sugar in 10.0 mL water                             +159.1∘

5.00 g sugar in 10.0 mL water                             +127.8∘

 

  1. A) -10.5∘
  2. B) +25.6∘
  3. C) +79.5∘
  4. D) -105∘
  5. E) +256∘

Answer:  D

Diff: 3

Section:  5.4

 

76) A newly isolated natural product was shown to be optically active. If a solution of 2.0 g in 10 mL of ethanol in a 50 cm tube gives a rotation of +2.57°, what is the specific rotation of this natural product?

Answer:  +2.57°

Diff: 3

Section:  5.4

77) A mixture of equal amounts of two enantiomers ________.

  1. A) is called a racemic mixture
  2. B) is optically inactive
  3. C) implies that the enantiomers are meso forms
  4. D) both A and B
  5. E) none of the above

Answer:  D

Diff: 2

Section:  5.6

 

78) If a mixture contains 75% of one compound and 25% of its enantiomer, what is the e.e. of the mixture?

  1. A) 100
  2. B) 75
  3. C) 50
  4. D) 25
  5. E) 3

Answer:  C

Diff: 2

Section:  5.7

 

 

79) Calculate the e.e. of a mixture containing 8.0 g of (-)-glyceraldehyde and 2.0 g of (+)-glyceraldehyde.

Answer:  60%

Diff: 2

Section:  5.7

 

80) A mixture of two enantiomers with a composition of 65.0% R has an observed rotation of -25.3° in a  polarimeter tube.  If the mixture has a concentration of 2.038 g/mL at 25°C, what is the predicted [α]25D of an optically pure sample of the S enantiomer?

  1. A) -25.3°
  2. B) -53.5°
  3. C) +12.4°
  4. D) +41.3°
  5. E) +53.5°

Answer:  D

Diff: 3

Section:  5.7

 

81) The specific rotation of pure (-)-2-butanol is -13.5°. What % of a mixture of the two enantiomeric forms is the (+)-form if the specific rotation of this mixture is +7.0°?

Answer:  76%

Diff: 3

Section:  5.7

82) (-)-Lactic acid has a specific rotation of -3.8°. What is the specific rotation of a solution containing 7.5 g of (-)-lactic acid and 2.5 g of (+)-lactic acid?

Answer:  -1.9°

Diff: 3

Section:  5.7

 

83) Explain the stereochemical relationship, if any, among the following two structures and describe whether or not they could be theoretically isolated from each other. (Note: Some H atoms are omitted for clarity.)

 

 

Answer:  These structures are conformationally dependent diastereomers.  They could not be isolated because they are actually the same molecule.

Diff: 3

Section:  5.8

 

 

84) Can a molecule be chiral if it contains no asymmetric carbons? Explain briefly.

Answer:  Yes. The presence of asymmetric carbons is not required for a molecule to be chiral. The only requirement is that the molecule be nonsuperimposable with its mirror image. Structural features other than asymmetric carbons can lead to chirality.

Diff: 2

Section:  5.9

 

85) Is the molecule shown below chiral or achiral?  Explain what this means.

 

 

Answer:  The molecule is chiral because its mirror image is nonsuperimposable.

Diff: 2

Section:  5.9

86) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the same compound?

 

Answer:  enantiomers

Diff: 3

Section:  5.9

 

87) Why is the following structure not a meso compound?

 

 

Answer:  The functional group at the top (aldehyde) is different from the bottom (alcohol) and thus there is no internal reflective plane in the molecule

Diff: 1

Section:  5.10

 

 

88) Draw the Fischer projection of (S)-2-hydroxybutanoic acid, CH3CH2CH(OH)COOH.

Answer:

Diff: 1

Section:  5.10

89) Draw the Fischer projection of (2R,4R)-2,4-dibromopentane.

Answer:

Diff: 2

Section:  5.10

 

90) Translate the structure below to a Fischer projection.

 

 

Answer:

 

Diff: 3

Section:  5.10

 

 

91) Provide a Fischer projection of (2R,3R,4S)-2,3,4-trichloroheptane.

Answer:

Diff: 3

Section:  5.10

92) Provide a Fischer projection of (2S,3S,4S)-2,3,4-trichloroheptane.

Answer:

Diff: 3

Section:  5.10

 

93) How many diastereomers are there of the molecule shown below?

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 6

Answer:  C

Diff: 1

Section:  5.11

 

94) Stereoisomers which are not mirror image isomers are ________.

Answer:  diastereomers

Diff: 1

Section:  5.11

95) Which of the following terms best describes the stereochemical relationship of the two compounds shown below in Fischer notation?

 

  1. A) enantiomers
  2. B) diastereomers
  3. C) constitutional isomers
  4. D) cis/trans – isomers
  5. E) meso – same structure

Answer:  B

Diff: 2

Section:  5.11

 

96) Which of the following terms correctly describe(s) the structural relationship between cis-1,3-dimethylcyclopentane and trans-1,3-dimethylcyclopentane?

  1. A) enantiomers
  2. B) diastereomers
  3. C) geometric isomers
  4. D) both A and C
  5. E) both B and C

Answer:  E

Diff: 2

Section:  5.11

 

97) What term describes the structural relationship between (E)- and (Z)-2-pentene?

  1. A) not isomers
  2. B) constitutional isomers
  3. C) enantiomers
  4. D) diastereomers
  5. E) conformers

Answer:  D

Diff: 2

Section:  5.11

 

98) What term describes the structural relationship between cis-1,2-dimethylcyclopentane and trans-1,2-dimethylcyclopentane?

  1. A) not isomers
  2. B) constitutional isomers
  3. C) enantiomers
  4. D) diastereomers
  5. E) conformers

Answer:  D

Diff: 2

Section:  5.11

 

99) If possible, draw the structure of any diastereomer of the molecule shown below.

 

Answer:

Diff: 2

Section:  5.11

 

100) If possible, draw the structure of any diastereomer of the molecule shown below.

 

Answer:

Diff: 2

Section:  5.11

 

101) Draw any diastereomer of the molecule shown below.

 

Answer:

Diff: 2

Section:  5.11

 

102) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the same compound?

 

Answer:  diastereomers

Diff: 2

Section:  5.11

 

103) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the same compound?

 

Answer:  the same compound

Diff: 2

Section:  5.11

 

104) One of the stereoisomers of the following oblongolide structure is a natural product isolated from a fungus and has been found to contain antiviral and cytotoxic activities (J. Nat. Prod. 2010, 55). How many stereoisomers exist for this structure?

 

 

  1. A) 6
  2. B) 12
  3. C) 32
  4. D) 64

Answer:  D

Diff: 2

Section:  5.11

 

105) Which of the following statements is (are) true for the compound (3R, 4R)-3,4-dimethylhexane?

  1. A) This compound is chiral.
  2. B) The enantiomer of this compound is (3S, 4S)-3,4-dimethylhexane.
  3. C) This compound is a diastereomer of (3R, 4S)-3,4-dimethylhexane.
  4. D) all of the above
  5. E) none of the above

Answer:  D

Diff: 2

Section:  5.11

 

106) What term describes the structural relationship between (2R,3R,4S)-2,3,4-trichloroheptane and (2R,3R,4R)-2,3,4-trichloroheptane?

  1. A) not isomers
  2. B) constitutional isomers
  3. C) enantiomers
  4. D) diastereomers
  5. E) conformers

Answer:  D

Diff: 2

Section:  5.11

 

107) How many diastereomers are there of the molecule shown below?

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 6

Answer:  E

Diff: 3

Section:  5.11

 

Use the following three structures to answer the questions below.

 

 

 

108) The relationship between I and III is: ________.

  1. A) same compound
  2. B) enantiomers
  3. C) diastereomers
  4. D) constitutional isomers

Answer:  C

Diff: 3

Section:  5.11

 

109) The relationship between I and II is: ________.

  1. A) same compound
  2. B) enantiomers
  3. C) diastereomers
  4. D) constitutional isomers

Answer:  C

Diff: 3

Section:  5.11

 

110) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the same compound?

 

Answer:  diastereomers

Diff: 3

Section:  5.11

 

111) Which of the following terms best describes the pair of compounds shown: enantiomers, diastereomers, or the same compound?

 

Answer:  the same compound

Diff: 3

Section:  5.11

 

112) Which of the following molecules, if isolated in its pure form, would demonstrate optical activity ?

 

 

  1. A) both IV and V
  2. B) both I and III
  3. C) only II
  4. D) both III and IV
  5. E) both I and V

Answer:  A

Diff: 3

Section:  5.12

 

113) Can the molecule shown below be properly described as a meso compound?

 

Answer:  Yes

Diff: 1

Section:  5.13

 

114) Can the molecule shown below be properly described as a meso compound?

 

Answer:  Yes

Diff: 1

Section:  5.13

 

115) How many enantiomers are there of the molecule shown below?

 

  1. A) 0
  2. B) 1
  3. C) 2
  4. D) 3
  5. E) 6

Answer:  A

Diff: 2

Section:  5.13

 

116) If possible, draw the structure of the enantiomer of the molecule shown below.

 

Answer:  The compound is an achiral, meso compound; it has no enantiomer.

Diff: 2

Section:  5.13

 

117) If possible, draw the enantiomer of the molecule shown below.

 

 

Answer:  This molecule is achiral.  It does not have an enantiomer.

Diff: 2

Section:  5.13

 

118) Which of the following statements is (are) true for the compound cis-1,2-dichlorocyclopropane?

  1. A) This compound is chiral.
  2. B) The enantiomer of this compound is trans-1,2-dichlorocyclopropane.
  3. C) This compound contains no asymmetric carbons.
  4. D) all of the above
  5. E) none of the above

Answer:  E

Diff: 2

Section:  5.13

 

119) Draw the structure of the meso form of 1,3-dichlorocyclopentane. Take particular care to indicate three-dimensional stereochemical detail properly.

Answer:

Diff: 2

Section:  5.13

 

120) Can the molecule shown below be properly described as a meso compound?

 

(CH3)2CHCH2CH3

Answer:  No

Diff: 2

Section:  5.13

 

121) Can the molecule shown below be properly described as a meso compound?

 

Answer:  No

Diff: 2

Section:  5.13

 

122) Can the molecule shown below be properly described as a meso compound?

 

Answer:  No

Diff: 2

Section:  5.13

 

123) Which of the structures above are meso structures?

  1. A) I
  2. B) II
  3. C) III
  4. D) II & III
  5. E) None of the previous

Answer:  A

Diff: 3

Section:  5.13

 

124) If possible, draw the enantiomer of the molecule shown below.

 

Answer:  This molecule is achiral.  It does not have an enantiomer.

Diff: 3

Section:  5.13

 

125) Is it theoretically possible to separate the pair of compounds below by distillation? Explain briefly.

 

Answer:  Yes. The molecules are related as diastereomers and hence have different boiling points.

Diff: 2

Section:  5.15

 

126) The process by which enantiomers are separated is called ________.

Answer:  resolution

Diff: 1

Section:  5.16

 

127) Briefly describe how two enantiomers might be separated.

Answer:  The two compounds can be converted to diastereomers, separated based on different physical properties of these diastereomers, and subsequently returned to their original forms after separation. Another method involves the chromatographic separation using a chiral stationary phase.

Diff: 2

Section:  5.16

 

128) Can one separate a mixture of enantiomers by gas chromatography?  Explain.

Answer:  Provided the compounds can be volatilized, a mixture of enantiomers can be separated by GC if an appropriate chiral column can be found.  Enantiomers will be retained differently by the chiral stationary phase of the column.

Diff: 3

Section:  5.16