Quiz 10 Flashcards

1
Q

If the conjugated diene is not symmetrical, what do you do?

A

Protonate to form the more stable carbocation

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2
Q

The thermodynamic product predominates when the reaction is…

A

reversible

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3
Q

The kinetic product predominates when the reaction is….

A

irreversible

1,2-addition

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4
Q

most of the time, the 1,2 addition product is the …

A

kinetic product

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5
Q

most of the time, the 1,4-addition product is the

A

thermodynamic product

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6
Q

6) Which of the following pairs are resonance structures?

A

C) III

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7
Q

7) Which of the following pairs are resonance structures?

A

C) III

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8
Q

8) Which of the following is not a resonance structure of the species shown?

A

D) IV

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12
Q

9) In which of the following does resonance delocalization of electron density not play a role?

A) allyl cation

B) benzyl anion

C) CO32-

D) O3

E) cyclohexyl radical

A

E) cyclohexyl radical

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13
Q

11) Due to electron delocalization, one would predict that the carbon-oxygen bond in acetamide, CH3CONH2, ________.

A) is nonpolar

B) has more double bond character than the carbon-oxygen bond of acetone, (CH3)2CO

C) is longer than the carbon-oxygen bond of dimethyl ether, (CH3)2O

D) is longer than the carbon-oxygen bond of acetone, (CH3)2CO

E) is formed by overlapping sp3 orbitals

A

D) is longer than the carbon-oxygen bond of acetone, (CH3)2CO

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14
Q

33) Identify the most stable structure(s).

A

Answer: A

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15
Q

36) Which of the following statements concerning resonance contributors and resonance hybrids is not correct?

A) The fewer nearly equivalent resonance contributors are in the structure, the greater the resonance energy.

B) A resonance hybrid is more stable than the predicted stability of any of its resonance contributors.

C) The greater the number of relatively stable resonance contributors, the greater the resonance energy.

D) The greater the predicted stability of a resonance contributor, the more it contributes to the resonance hybrid.

E) none of the above

A

A) The fewer nearly equivalent resonance contributors are in the structure, the greater the resonance energy.

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16
Q

38) Aromatic molecules contain ________ π electrons.

A) no

B) 4n + 2 (with n an integer)

C) 4n + 2 (where n = 0.5)

D) 4n (with n an integer)

E) unpaired

A

B) 4n + 2 (with n an integer)

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17
Q

43) Which of the following is an aromatic hydrocarbon?

A

C) III

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18
Q

44) Which of the following is aromatic?

A

C) III

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19
Q

45) Which of the structures below would be aromatic?

A

C) III and IV

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20
Q

46) Which of the following is aromatic?

A

B) II

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21
Q

47) Which of the following is aromatic?

A) cyclopentadienyl cation

B) 1,3-cyclohexadiene

C) cyclobutenyl anion

D) 1,3,5-hexatriene

E) cycloheptatrienyl cation

A

E) cycloheptatrienyl cation

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22
Q

49) Which of the following compounds is aromatic?

A

D) IV

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23
Q

50) Which of the following is aromatic?

A

A) I

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24
Q

55) Which of the following is antiaromatic?

A

D) IV

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25
Q

64) Which of the following statements about the π molecular orbital description of cyclobutadiene is not correct?

A) Cyclobutadiene has two degenerate nonbonding π molecular orbitals.

B) Cyclobutadiene has a single bonding π molecular orbital.

C) Cyclobutadiene has two electrons in nonbonding π molecular orbitals.

D) Cyclobutadiene has one electron in an antibonding π molecular orbital which makes it antiaromatic.

E) none of the above

A

D) Cyclobutadiene has one electron in an antibonding π molecular orbital which makes it antiaromatic.

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26
Q

66) Which of the following is an allylic cation?

A

B) II

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27
Q

67) Which of the following is a benzylic cation?

A

D) IV

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28
Q

68) Which of the following is the most stable cation?

A

C) III

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29
Q

69) How many allylic hydrogen atoms are present in the following molecule?

A

E) zero

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30
Q

70) How many benzylic hydrogens are present in the following molecule?

A

E) zero

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31
Q

71) Which of the following is the most stable diene?

A

C) III

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32
Q

74) What descriptive term is applied to the type of diene represented by 2,4-hexadiene?

A) conjugated diene

B) cumulated diene

C) isolated diene

D) alkynyl diene

E) none of the above

A

A) conjugated diene

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33
Q

75) What descriptive term is applied to the type of diene represented by 1, 5-octadiene?

A) conjugated diene

B) cumulated diene

C) isolated diene

D) alkynyl diene

E) none of the above

A

C) isolated diene

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34
Q

76) Which of the following is a cumulated diene?

A

C) III

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35
Q

77) Which of the following is a conjugated diene?

A

A) I

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36
Q

86) Identify the most stable carbocation.

A
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37
Q

87) Identify the most stable carbocation.

A
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38
Q

96) Which of the following is/are the major product(s) of the following reaction?

A

A) I

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39
Q

97) Which of the following is the strongest acid?

A
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40
Q

98) Which of the following is the strongest acid?

A

D) IV

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41
Q

103) Which of the following is/are the main product(s) of the following reaction?

A

E) A and C

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42
Q

104) What is/are the product(s) from the following reaction?

A

D) I is major, II is minor

43
Q

105) What is/are the product(s) of the following reaction?

A

E) I and III

44
Q

106) What compound results from the 1, 4-addition of one equivalent of HBr to 1, 3-butadiene?

A) 1-bromo-1-butene

B) 2-bromo-2-butene

C) 4-bromo-1-butene

D) 3-bromo-1-butene

E) 1-bromo-2-butene

A

E) 1-bromo-2-butene

45
Q

107) Which of the following is/are the major product(s) of the following reaction?

A

C) II

46
Q

108) What is/are the product(s) from the following reaction?

A

A) I and II

47
Q

111) Give the major organic product for the reaction.

A
48
Q

112) Give the major organic product for the reaction.

A
49
Q

113) Give the major organic product(s) for the reaction.

A

Answer: A, B

50
Q

115) Give the major organic product(s) for the reaction.

A

Answer: D, E

51
Q

117) What is the thermodynamic product for the following reaction?

A

D) IV

52
Q

118) What is the kinetic product for the following reaction?

A

E) V

53
Q

119) Which of the following is a correct statement considering thermodynamic versus kinetic control of organic reactions?

A) When a reaction is under thermodynamic control, the relative amounts of products depend on the activation energies of the steps leading to their formation.

B) The kinetic product always predominates when the reaction is reversible.

C) Higher temperatures and longer reaction times typically favor the kinetic product over the thermodynamic product.

D) When the products are in equilibrium under the reaction conditions, the relative amounts of products depend on their stabilities and the reaction is under thermodynamic control.

E) none of the above

A

D) When the products are in equilibrium under the reaction conditions, the relative amounts of products depend on their stabilities and the reaction is under thermodynamic control.

54
Q

120) What is/are the product(s) from the following reaction?

A

B) II Major, III Minor

55
Q

121) What is/are the product(s) from the following reaction?

A

C) III only

56
Q

128) What is the product of the following reaction?

A

E) V

57
Q

129) What is the product from the following reaction?

A

B) II

58
Q

130) Which of the following conjugated dienes would not react with a dieneophile in a Diels-Alder reaction?

A

E) I and III

59
Q

131) Which of the following dienes is the most reactive in a Diels-Alder reaction?

A

C) III

60
Q

132) What diene and what dieneophile would be used to synthesize the following compound?

A

B) II

61
Q

133) Which of the following terms best describes a Diels-Alder reaction?

A) a [4+2] cycloaddition

B) a [2+2] cycloaddition

C) a sigmatropic rearrangement

D) a 1, 3-dipolar cycloaddition

E) a substitution reaction

A

A) a [4+2] cycloaddition

62
Q

134) When 1, 3-butadiene reacts with CH2CHCN, which of the terms below best describes the product mixture?

A) a mixture of two diastereomers

B) a single compound

C) a racemic mixture

D) optically active

E) a mixture of bicyclic compounds

A

C) a racemic mixture

63
Q

135) The Diels-Alder reaction is a concerted reaction; this means that ________.

A) a mixture of endo and exo products is formed

B) all bond making and bond breaking occurs simultaneously

C) the products contain rings

D) the reaction follows Markovnikov’s rule

E) the reaction is highly endothermic

A

B) all bond making and bond breaking occurs simultaneously

64
Q

136) Which of the following statements is (are) true of the Diels-Alder reaction?

A) When the diene is electron-rich, the reaction works best when the dienophile contains one or more electron-withdrawing groups conjugated to its CC.

B) Substituents which are cis in the dienophile remain cis in the product.

C) Dienes which cannot achieve an s-cis conformation do not react in Diels-Alder reactions.

D) Secondary orbital interactions typically cause the endo product to be favored kinetically over the exo.

E) all of the above

A

E) all of the above

65
Q

137) When 1, 3-cyclopentadiene reacts with the cis-isomer of NCCH=CHCN, the major product is ________.

A) optically active

B) a meso compound

C) a racemic mixture

D) a spirocyclic compound

E) a fused bicyclic compound

A

D) a spirocyclic compound

66
Q

158) Give the major organic product for the reaction.

A
67
Q

159) Give the major organic product for the reaction.

A
68
Q

160) Give the major organic product for the reaction.

A

E) No reaction

69
Q

164) Which of the following is an isolated diene?

A

D) IV

70
Q

166) Give the major organic product for the reaction.

A
71
Q
A
72
Q

If the conjugated diene is not symmetrical, what do you do?

A

Protonate to form the more stable carbocation

73
Q

The thermodynamic product predominates when the reaction is…

A

reversible

74
Q

The kinetic product predominates when the reaction is….

A

irreversible

1,2-addition

75
Q

most of the time, the 1,2 addition product is the …

A

kinetic product

76
Q

most of the time, the 1,4-addition product is the

A

thermodynamic product

77
Q

6) Which of the following pairs are resonance structures?

A

C) III

78
Q

7) Which of the following pairs are resonance structures?

A

C) III

79
Q

8) Which of the following is not a resonance structure of the species shown?

A

D) IV

81
Q
  1. Which of the following reaction coordinate diagrams explains the formation of different thermodynamic (T) and kinetic products from the same reactants (R)?
A

C. 3

84
Q

9) In which of the following does resonance delocalization of electron density not play a role?

A) allyl cation

B) benzyl anion

C) CO32-

D) O3

E) cyclohexyl radical

A

E) cyclohexyl radical

86
Q

What is the reactive intermediate in the reaction of 1,3-butadiene with HBr resulting in 1,2-addition?
A. cyclic bromonium cation
B. allylic cation
C. allylic radical
D. dienophile

A

B. allylic cation

87
Q
A

C. only 1 and 2

88
Q
A

B. only 2

89
Q
A

C. 3,4-dimethyl-1,3-pentadiene

90
Q
A

C. 3-methyl-1,4-pentadiene

91
Q
A

A. (3S,4E)-3-ethyl-3,4-dimethyl-1,4-hexadiene

92
Q
A

C. 3

93
Q
A

B. 3 > 1 > 2

94
Q
A

D. only 1 and 4

95
Q
A

B. only 1 and 2

96
Q
A

C. only 2 and 4

97
Q
A

B. only 2

98
Q
A

B. only 3

99
Q
A

C. only 3

100
Q

Which of the following terms describes the mechanism for the addition of Br2 to butadiene?
A. electrophilic addition
B. nucleophilic addition
C. pericyclic addition
D. conjugate addition

A

A. electrophilic addition

101
Q

Which of the following is not a major organic product obtained from the addition of 1 mole of bromine to (E)-1,3-pentadiene?
A. (E)-4,5-dibromo-2-pentene
B. 3,4-dibromo-1-pentene
C. (E)-1,4-dibromo-2-pentene
D. (E)-1,2-dibromo-2-pentene

A

D. (E)-1,2-dibromo-2-pentene

102
Q

What is the thermodynamic product obtained from the addition of 1 mole of bromine to 1,3-butadiene?
A. 3,4-dibromo-1-butene
B. (E)-1,4-dibromo-2-butene
C. (Z)-1,4-dibromo-2-butene
D. (Z)-2,3-dibromo-2-butene

A

B. (E)-1,4-dibromo-2-butene

103
Q

What is the kinetic product obtained from the addition of 1 mole of bromine to 1,3-butadiene?
A. 3,4-dibromo-1-butene
B. (E)-1,4-dibromo-2-butene
C. (Z)-1,4-dibromo-2-butene
D. (Z)-2,3-dibromo-2-butene

A

A. 3,4-dibromo-1-butene