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Chapter 9Multiple Choice Questions:
Topic: Addition Reaction MechanismsSection: 9.1Difficulty Level: Easy
1. In an addition reaction to an alkene, the π bond plays the role of:A) nucleophileB) electrophileC) leaving groupD) A and BE) B and CAns: A
Topic: Addition Reaction MechanismsSection: 9.1Difficulty Level: Moderate
2. Addition reactions of alkenes are characterized by:A) formation of a π bond B) addition of two groups across a double bondC) breaking of a π bond D) A and BE) B and CAns: E
Topic: Addition vs. Elimination Thermodynamic PerspectiveSection: 9.2Difficulty Level: Easy
3. The decrease in entropy (the S value is negative) observed for alkene addition reactions results from:
A) the breaking of a π and bond.B) the formation of two bonds.C) the reaction being exothermic.D) two molecules reacting to form a single molecule.E) the temperature dependence of the S term.Ans: D
Topic: Addition vs. Elimination Thermodynamic PerspectiveSection: 9.2Difficulty Level: Easy
4. In a reaction where addition and elimination reactions are in competition, which of the following statements is most correct?
A) Addition and elimination reactions are favored at low temperatures.B) Addition and elimination reactions are favored at high temperatures.C) Only addition reactions are favored at low temperatures.D) Only elimination reactions are favored at low temperatures.E) Addition and elimination reactions are disfavored at low temperatures.Ans: C
Topic: Addition vs. Elimination Thermodynamic PerspectiveSection: 9.2Difficulty Level: Easy
5. Which statement is true about the temperature dependence of an addition reaction?A) Addition reactions are thermodynamically favorable at all temperatures.B) Addition reactions are thermodynamically disfavored at all temperatures.C) Addition reactions are thermodynamically favorable at low temperatures.D) Addition reactions are thermodynamically favorable at high temperatures.E) Addition reactions are thermodynamically impossible.Ans: C
Topic: Addition vs. Elimination Thermodynamic PerspectiveSection: 9.2Difficulty Level: Moderate
6. For an addition reaction, why does the free energy term, G, become more positive with increasing temperature?
A) The positive entropy term dominates at high temperature.B) The negative entropy term dominates at high temperature.C) The positive enthalpy term dominates at high temperature.D) The negative enthalpy term dominates at high temperature.E) The enthalpy and entropy terms cancel at high temperature.Ans: A
Topic: Addition vs. Elimination Thermodynamic PerspectiveSection: 9.2Difficulty Level: Hard
7. Addition reactions are favorable at low temperatures because:A) the positive enthalpy term is larger than the negative entropy term.B) the negative enthalpy term is larger than the positive entropy term.C) the positive enthalpy term is smaller than the negative entropy term.D) the negative enthalpy term is smaller than the positive entropy term.E) the enthalpy and entropy terms are equal.Ans: B
Topic: HydrohalogenationSection: 9.3Difficulty Level: Easy
8. Which of the molecules below would be the expected product for hydrohalogenation of the following alkene:
A)
B)C)
D)
E)Ans: E
Topic: HydrohalogenationSection: 9.3Difficulty Level: Easy
9. In the addition reaction of HI to 2-methyl-2-butene, the Markovnikov addition mechanism involves:
A) attack of 2-methyl-2-butene initiated by an iodide ion.B) attack of 2-methyl-2-butene initiated by an iodine atom.C) isomerization of 2-iodo-2-methylbutene.D) formation of a carbocation at carbon two (C-2).E) formation of carbocation at carbon three (C-3).
Ans: D
Topic: HydrohalogenationSection: 9.3Difficulty Level: Easy
10. The expected Markovnikov addition product of HI to 2-methyl-2-butene is:A) 2-iodopentaneB) 2-iodo-2-methylbutaneC) 1-iodo-2-methylbutaneD) 2-iodo-1-methylbutaneE) 3-iodo-2-methylbutane
Ans: BTopic: HydrohalogenationSection: 9.3Difficulty Level: Easy
11. The regioselectivity and stereospecificity in hydrohalogenation of an alkene is best described as:
A) Markovnikov orientation with syn-additionB) Markovnikov orientation with anti-additionC) anti-Markovnikov orientation with syn-additionD) anti-Markovnikov orientation with anti-additionE) Markonikov orientation with both syn- and anti-additionAns: E
Topic: HydrohalogenationSection: 9.3Difficulty Level: Easy
12. Which of the structures shown depicts the most stable carbocation intermediate formed in a hydrohalogenation reaction?
A) IB) IIC) IIID) IVE) VAns: B
Topic: Hydrohalogenation Section: 9.3Difficulty Level: Easy
13. What compound is the expected product upon Markovnikov hydrohalogenation with HBr of the alkene shown below?
A)
B)
C)
D)
E)Ans: B
Topic: HydrohalogenationSection: 9.3Difficulty Level: Easy
14. The expected major product of the following reaction is:
A)
B)
C)
D)
E)Ans: C
Topic: HydrohalogenationSection: 9.3Difficulty Level: Easy
15. The expected major product of the following reaction is:
A)
B)
C)
D)
E)Ans: A
Topic: HydrohalogenationSection: 9.3Difficulty Level: Easy
16. What is the expected major product for the following reaction?
A) IB) IIC) IIID) IVE) VAns: D
Topic: Anti-Markovnikov HydrohalogenationSection: 9.3Difficulty Level: Easy
17. Which of the molecules below arises from anti-Markovnikov hydrohalogenation with HBr of the alkene shown?
A)
B)
C)
D)
E)Ans: C
Topic: Stereochemistry of HydrohalogenationSection: 9.3Difficulty Level: Easy
18. Which of the alkenes shown below would produce a chirality center upon hydrohalogenation?
A)
B)
C)
D)
Topic: Stereochemistry of HydrohalogenationSection: 9.3Difficulty Level: Easy
19. What is the major product for the following reaction?
A)
B)
C)
D)
E)Ans: A
Topic: Stereochemistry of HydrohalogenationSection: 9.3Difficulty Level: Moderate
20. Which of the alkenes below would be expected to produce a chirality center upon hydrohalogenation in the presence of peroxide?
A)
B)C)
D)
E)Ans: B
Topic: HydrohalogenationSection: 9.3Difficulty Level: Moderate
21. Which of the given reaction schemes would produce the molecule shown below?
A)
B)
C)D) Both A and BE) Both B and CAns: E
Topic: Stereochemistry of HydrohalogenationSection: 9.3Difficulty Level: Moderate
22. Which of the molecules below are enantiomers, formed as products upon reaction of HBr with 4-methylpent-1-ene?
A) I and IIB) II and IIIC) III and IVD) I and IIIE) II and IVAns: E
Topic: Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Moderate
23. Which of the following carbocations is likely to undergo rearrangement through a methyl shift?
A) IB) IIC) IIID) I and IIE) II and IIIAns: D
Topic: Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Moderate
24. Which of the following carbocations is likely to undergo rearrangement through a hydride shift?
A) IB) IIC) IIID) I and IIE) II and IIIAns: D
Topic: Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Moderate
25. The expected major product(s) of HCl addition to the alkene shown would be:
A) I and IIB) II and IIIC) I and IVD) VE) All of the above are equally likely to formAns: A
Topic: Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Moderate
26. The expected major product(s) of HBr addition to the alkene shown would be:
A)
B)
C)
D)
E)Ans: A
Topic: Stereochemistry of Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Moderate
27. The reaction shown below would be expected to produce as major products which of the following compounds?
A)
B)
C)
D)
E)Ans: D
Topic: Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Hard
28. What is the IUPAC name of the expected major product formed upon reaction of HCl with 3-methyl-1-butene?
A) 1-Chloro-2-methylbutaneB) 1-Chloro-3-methylbutaneC) 2-Chloro-2-methylbutaneD) 2-Chloro-3-methylbutaneE) 1-Chloropentane
Ans: C
Topic: Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Hard
29. Select the expected major product(s) of the following reaction:
A)
B)
C)D) A and BE) A and CAns: C
Topic: Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Hard
30. Identify the expected product(s) for the reaction shown below?
A)
B)
C)
D)
E)Ans: C
Topic: Acid Catalyzed HydrationSection: 9.4Difficulty Level: Easy
31. The regioselectivity and stereospecificity in the acid-catalyzed hydration of an alkene is best described as:
A) Markovnikov orientation with syn-additionB) Markovnikov orientation with anti-additionC) anti-Markovnikov orientation with syn-additionD) anti-Markovnikov orientation with anti-additionE) Markonikov orientation with both syn- and anti-additionAns: E
Topic: Acid Catalyzed HydrationSection: 9.4Difficulty Level: Easy
32. The expected major product of the following reaction is:
A) IB) IIC) IIID) IVE) VAns: D
Topic: Acid Catalyzed HydrationSection: 9.4Difficulty Level: Easy
33. The expected major product of the following reaction is:
A) IB) IIC) IIID) IVE) VAns: C
Topic: Acid Catalyzed HydrationSection: 9.4Difficulty Level: Easy
34. The expected major product of the following reaction is:
A)
B)
C)
D)
E)
Ans: DTopic: Acid Catalyzed HydrationSection: 9.4Difficulty Level: Easy
35. Treatment of 1-methylcyclohexene with H3O+ would be expected to yield as the major product which of the molecules below?
A) I and IIIB) IIC) III and VD) IVE) I, III and VAns: D
Topic: Acid Catalyzed HydrationSection: 9.4Difficulty Level: Moderate
36. Treatment of (S)-6-chloro-1-methyl-1-cyclohexene with H3O+ is expected to produce which of the following?
A) I and IIIB) IIC) III and VD) IVE) I, III and VAns: B
Topic: Acid Catalyzed HydrationSection: 9.4Difficulty Level: Hard
37. What is the expected major product for the following reaction?
A)
B)
C)
D)
E)Ans: A
Topic: Oxymercuration-DemercurationSection: 9.5Difficulty Level: Easy
38. The regioselectivity and stereospecificity in the oxymercuration-demercuration of an alkene is best described as:
A) Markovnikov orientation with syn-additionB) Markovnikov orientation with anti-additionC) anti-Markovnikov orientation with syn-additionD) anti-Markovnikov orientation with anti-additionE) Markonikov orientation with both syn- and anti-additionAns: B
Topic: Oxymercuration-DemercurationSection: 9.5Difficulty Level: Easy
39. What is the expected major product for the following reaction?
A)
B)
C)
D)
E)Ans: B
Topic: Oxymercuration-DemercurationSection: 9.5Difficulty Level: Easy
40. What synthetic goal is achieved by subjecting an alkene to an oxymercuration-demercuration reaction sequence?
A) Markovnikov addition of H2O, promoting skeletal rearrangementB) Markovnikov addition of H2O, preventing skeletal rearrangementC) anti-Markovnikov addition of H2O, promoting skeletal rearrangementD) anti-Markovnikov addition of H2O, preventing skeletal rearrangementE) anti-Markovnikov addition of H2O, syn-hydroxylationAns: B
Topic: Oxymercuration-DemercurationSection: 9.5Difficulty Level: Easy
41. What is the expected major product for the following reaction?
A)
B)
C)
D)
E)Ans: C
Topic: Oxymercuration-DemercurationSection: 9.5Difficulty Level: Easy
42. What is the expected major product for the following reaction?
A)
B)
C)
D)
E)Ans: D
Topic: Oxymercuration-DemercurationSection: 9.5Difficulty Level: Easy
43. What is the expected major product for the following reaction?
A)
B)
C)
D)
E)Ans: B
Topic: Oxymercuration-DemercurationSection: 9.5Difficulty Level: Moderate
44. When an alkene is subjected to treatment with Hg(OAc)2 in alcohol, followed by reaction with NaBH4, what functional group is formed?
A) etherB) epoxideC) alkaneD) syn diolE) alkyneAns: A
Topic: Hydroboration-OxidationSection: 9.6Difficulty Level: Easy
45. The regioselectivity and stereospecificity in the hydroboration-oxidation of an alkene is best described as:
A) Markovnikov orientation with syn-additionB) Markovnikov orientation with anti-additionC) Anti-Markovnikov orientation with syn-additionD) Anti-Markovnikov orientation with anti-additionE) Markovnikov orientation with both syn- and anti-additionAns: C
Topic: Hydroboration-OxidationSection: 9.6Difficulty Level: Easy
46. What reagents are needed to accomplish the following transformation?
A) H2O/H+
B) H2O/PeroxideC) OH–
D) BH3
E) 1. BH3, 2. HO–, H2O2, H2OAns: E
Topic: Hydroboration-OxidationSection: 9.6Difficulty Level: Easy
47. What is the expected major product for the following reaction sequence?
A)
B)
C)
D)
E)Ans: E
Topic: Hydroboration-OxidationSection: 9.6Difficulty Level: Easy
48. What is the expected major product for the following reaction sequence?
A) IB) IIC) IIID) I and IIE) I and IIIAns: E
Topic: Hydroboration-OxidationSection: 9.6Difficulty Level: Moderate
49. What is the expected major product for the following reaction sequence?
A)
B)
C)
D)
E)Ans: E
Topic: Hydroboration-OxidationSection: 9.6Difficulty Level: Moderate
50. What is the expected major product for the following reaction sequence?
A) IB) IIC) IIID) IVE) VAns: D
Topic: Hydroboration-OxidationSection: 9.6Difficulty Level: Moderate
51. What is the expected major product for the following reaction sequence?
A)
B)
C)
D)
E)
Topic: Catalytic HydrogenationSection: 9.7Difficulty Level: Easy
52. What is the expected major product for the hydrogenation of an alkene?A) dihaloalkaneB) alkaneC) haloalkaneD) alcoholE) etherAns: B
Topic: Catalytic HydrogenationSection: 9.7Difficulty Level: Easy
53. Provide the major organic product(s) for the reaction shown below.
A)
B)
C)
D)
E)Ans: B
Topic: Catalytic HydrogenationSection: 9.7Difficulty Level: Easy
54. What product is formed when 5-chloro-1-methylcyclohexene is reduced with a Pt catalyst and H2?
A) 1-chloro-5-methylcyclohexaneB) 1-chloro-3-methylcyclohexaneC) 5-chloro-1-methylcyclohexaneD) 3-chloro-1-methylcyclohexaneE) None of the above
Ans: BTopic: Catalytic HydrogenationSection: 9.7Difficulty Level: Easy
55. What product is formed when trans-1,2-dimethylcyclohexane is reacted with Pd/C and H2?
A) No reactionB) cis-1,2-dimethylcyclohexaneC) trans-3,4-dimethylhexaneD) trans-1,2-dimethylhexaneE) None of the aboveAns: A
Topic: Catalytic HydrogenationSection: 9.7Difficulty Level: Easy
56. Which of the following reagents accomplishes the transformation shown below?
A) H2/HClB) H2/H2SO4
C) H2/NiD) H2O/NiE) H2O/H2SO4
Ans: C
Topic: Catalytic HydrogenationSection: 9.7Difficulty Level: Easy
57. Which of the reagents below are expected to convert cyclopentene into cyclopentane?
A) H2 and NiB) H2OC) HeatD) Zn, H3O+
E) LightAns: A
Topic: Catalytic HydrogenationSection: 9.7Difficulty Level: Easy
58. Which alkene would yield 3-methylpentane upon subjection to catalytic hydrogenation?
A) IB) IIC) IIID) IVE) VAns: B
Topic: Catalytic HydrogenationSection: 9.7Difficulty Level: Easy
59. How many moles of hydrogen (H2) are consumed in the catalytic reduction of 1 mole of 1,3-dibromocyclohexa-1,4-diene?
A) 12
B) 2C) 3D) 4E) None of the aboveAns: B
Topic: Catalytic HydrogenationSection: 9.7Difficulty Level: Easy
60. How many moles of hydrogen (H2) are required to completely reduce 1 mole of cis-2,3,3-trimethylhepta-1,5-diene?
A) 02
B) 1C) 2D) 3E) 4Ans: C
Topic: Catalytic Hydrogenation Section: 9.7Difficulty Level: Easy
61. Which of the catalysts listed are used in the homogenous catalytic hydrogenation of alkenes?I) Ni II) Pt III) Wilkinson
A) I B) IIC) IIID) I and IIE) II and IIIAns: C
Topic: Catalytic Hydrogenation Section: 9.7Difficulty Level: Easy
62. In conducting a catalytic hydrogenation of an alkene, which catalyst listed is most likely soluble in the reaction medium?
A) NiB) PtC) PdD) WilkinsonE) All of the above are solubleAns: D
Topic: Catalytic Hydrogenation Section: 9.7Difficulty Level: Easy
63. Wilkinson’s catalyst accomplishes which of the listed molecular transformations?A) syn addition of H2 to an alkeneB) anti addition of H2 to an alkene C) syn dihydroxylation of an alkeneD) anti dihydroxylation of an alkeneE) oxidative cleavage of an alkeneAns: A
Topic: Catalytic Hydrogenation Section: 9.7Difficulty Level: Easy
64. For the catalytic hydrogenation of alkenes, select from below those most likely to function as a homogenous catalyst?
A) WilkinsonB) NiC) PdD) PtE) AuAns: A
Topic: Catalytic HydrogenationSection: 9.7Difficulty Level: Moderate
65. Which of the following will yield 2-methylpentane upon catalytic hydrogenation?A) 2-methyl-1-pentene2
B) 2-methyl-2-penteneC) 4-methyl-2-penteneD) 4-methyl-1-penteneE) All of the aboveAns: E
Topic: Catalytic HydrogenationSection: 9.7Difficulty Level: Moderate
66. For the complete reduction of 1 mole of (3E,5E)-hepta-1,3,5-triene with H2 using a Pd catalyst, how many moles of H2 are consumed?
A) 1B) 2C) 3D) 4E) 5Ans: C
Topic: Catalytic Hydrogenation and StereospecificitySection: 9.7Difficulty Level: Moderate
67. What products are produced from the reaction below?
A) I, II, IIIB) II, III, IVC) I and IVD) II and IIIE) I, II, III, and IVAns: A
Topic: Catalytic Hydrogenation and StereospecificitySection: 9.7Difficulty Level: Moderate
68. Identify the major organic product generated from the reaction shown.
A) IB) IIC) IIID) IVE) VAns: B
Topic: HalogenationSection: 9.8Difficulty Level: Easy
69. Which reaction intermediate is formed when 4-methylcyclohexene reacts with Br2
dissolved in CCl4?
A) IB) IIC) IIID) IVE) VAns: B
Topic: HalogenationSection: 9.8Difficulty Level: Easy
70. What is the expected major product upon reaction of 1-pentene with Cl2?A) 1-chloropentaneB) 2-chloropentaneC) 1,1-dichloropentaneD) 2,2-dichloropentaneE) 1,2-dichloropentaneAns: E
Topic: Halogenation and StereospecificitySection: 9.8Difficulty Level: Easy
71. Treating 2-methyl-2-pentene with Br2 is expected to produce which of the following as the major product?
A) 2,3-dibromo-2-methylpentaneB) 2,2-dibromo-2-methylpentaneC) 3,3-dibromo-2-methylpentaneD) 2-bromo-2-methylpentaneE) 3-dibromo-2-methylpentane
Ans: A
Topic: Halohydrin FormationSection: 9.8Difficulty Level: Easy
72. The expected intermediate formed during a halohydrin reaction is: A) a halonium ion.B) the most stable carbocation with OH on the adjacent carbon.C) the most stable carbocation with X on the adjacent carbon.D) a cyclic oxonium ion.E) the most stable carbanion.Ans: A
Topic: Halohydrin FormationSection: 9.8Difficulty Level: Easy
73. What major product is expected from the following reaction?
A) IB) IIC) IIID) IVE) VAns: D
Topic: Halohydrin FormationSection: 9.8Difficulty Level: Moderate
74. What is the expected major product for the following reaction?
A) IB) IIC) IIID) IVE) VAns: D
Topic: Halogenation and StereospecificitySection: 9.8Difficulty Level: Moderate
75. Which of the statements is most correct regarding the products expected from the halogenation reaction shown below?
A) Equal amounts of I and II are produced.B) Equal amounts of III and IV are produced.C) Equal amounts of I and IV are produced.D) Equal amounts of II and III are produced.E) Equal amounts of I and III are produced.Ans: B
Topic: Halogenation and StereospecificitySection: 9.8Difficulty Level: Moderate
76. For the halogenation reaction shown below, which of the following statements is correct regarding the expected products?
A) Equal amounts of I and II producedB) Equal amounts of III and IV producedC) Equal amounts of I and IV producedD) Equal amounts of II and III producedE) Equal amounts of I and III producedAns: A
Topic: Halogenation, Regioselectivity, and StereospecificitySection: 9.8Difficulty Level: Hard
77. The reaction of Br2 with 1-methylcyclohexene, in the presence of ethylamine (EtNH2), is expected to produce which of the following as the major product?
A) IB) IIC) IIID) IVE) VAns: D
Topic: anti dihydroxylationSection: 9.9Difficulty Level: Easy
78. For the reaction sequence below, identify the expected major products.
A)
B)
C)
D)
E)Ans: B
Topic: anti dihydroxylationSection: 9.9Difficulty Level: Moderate
79. For the reaction sequence below, identify the expected major product(s).
A) IB) IIC) IIID) I and IIIE) II and III
Ans: DTopic: anti dihydroxylationSection: 9.9Difficulty Level: Moderate
80. What are the major products for the following reaction sequence?
A) I and IIB) II and IIIC) III and IVD) I and IIIE) II and IVAns: E
Topic: anti dihydroxylationSection: 9.9Difficulty Level: Moderate
81. What is the major product for the following reaction sequence?
A) IB) IIC) IIID) IVE) V
Ans: DTopic: anti dihydroxylationSection: 9.9Difficulty Level: Hard
82. For the following dihydroxylation reaction which of the following statements is correct regarding the expected products?
A) Equal amounts of I and II producedB) Equal amounts of III and IV producedC) Equal amounts of I and IV producedD) Equal amounts of II and III producedE) Equal amounts of I and III producedAns: E
Topic: anti dihydroxylationSection: 9.9Difficulty Level: Hard
83. An unknown alkene was reacted with MCPBA in dichloromethane, followed by work-up with H2O/H+. A racemic mixture of the compound shown below was obtained. What is correct name of the starting alkene?
A) (Z)-3-methylpent-2-eneB) (E)-3-methylpent-2-eneC) 2-methylpent-2-eneD) 2,3-dimethylbut-2-eneE) none of the aboveAns: A
Topic: syn DihydroxylationSection: 9.10Difficulty Level: Easy
84. Identify the expected major organic product resulting from the following reaction sequence.
A) IB) IIC) IIID) IVE) VAns: A
Topic: syn DihydroxylationSection: 9.10Difficulty Level: Easy
85. Treatment of 1,2-dimethylcyclopentene with OsO4, followed by aqueous NaHSO3, produces which of the following:
A) IB) IIC) IIID) IVE) VAns: A
Topic: syn DihydroxylationSection: 9.10Difficulty Level: Easy
86. Identify the expected major organic product generated from the reaction sequence shown.
A) IB) IIC) IIID) IVE) VAns: B
Topic: syn DihydroxylationSection: 9.10Difficulty Level: Easy
87. Which of the following alkene addition reactions occur(s) specifically in syn fashion?
A) dihydroxylation using OsO4, H2O2
B) addition of H2
C) hydroborationD) addition of HClE) A, B, and CAns: E
Topic: syn DihydroxylationSection: 9.10Difficulty Level: Easy
88. What is the expected major product for the following reaction sequence?
A)
B)
C)
D)E) None of the aboveAns: A
Topic: Oxidative CleavageSection: 9.11Difficulty Level: Easy
89. Provide the expected major organic product of the reaction sequence shown.
A) I and IIB) IV and VC) I onlyD) II onlyE) III only
Ans: ETopic: Oxidative CleavageSection: 9.11Difficulty Level: Easy
90. Which of the following reagents effectively cleaves a carbon-carbon double bond?A) Cl2/hυ
B) C) H2SO4
D) cold KMnO4
E) O3/DMSAns: E
Topic: Oxidative CleavageSection: 9.11Difficulty Level: Moderate
91. How many carbonyls are generated upon treatment of the molecule below with ozone, followed by zinc metal and water?
A) 1B) 2C) 3D) 4E) 8Ans: E
Topic: Oxidative CleavageSection: 9.11Difficulty Level: Moderate
92. Of the alkenes shown, which would produce the product shown below, upon treatment with ozone, followed by zinc metal and water?
A) IB) IIC) IIID) IVE) VAns: B
Topic: Oxidative CleavageSection: 9.11Difficulty Level: Moderate
93. What is the expected major product of the reaction sequence shown below?
A) IB) IIC) IIID) IVE) VAns: A
Topic: Oxidative CleavageSection: 9.11Difficulty Level: Moderate
94. What are the expected major products from the reaction sequence shown below?
A) IB) IIC) IIID) IVE) VAns: A
Topic: Predicting Addition ProductsSection: 9.12Difficulty Level: Easy
95. Which of the following alkene addition reactions occur(s) specifically in an anti fashion?
A) hydroboration-oxidationB) addition of Br2
C) addition of H2
D) addition of H2O in dilute acidE) both A and BAns: B
Topic: Predicting Addition ProductsSection: 9.12Difficulty Level: Easy
96. The Markovnikov product, resulting from an addition reaction to an unsymmetrical alkene, is formed because:
A) the product is statistically favored.B) steric hindrance favors its formation.C) the reaction proceeds via the more/most stable carbocation.D) the reaction forms the more/most stable product.E) All of the above are valid reasonsAns: C
Topic: Predicting Addition ProductsSection: 9.12Difficulty Level: Easy
97. What is the expected major product for the following reaction sequence?
A)
B)
C)
D)
E)
Ans: ATopic: Predicting Addition ProductsSection: 9.12Difficulty Level: Easy
98. What reagents are most likely to accomplish the transformation shown below?
A) 1. BH3 / 2. HO–, H2O2, H2OB) H+, H2OC) 1. Hg(OAc)2, H2O, THF / 2. NaBH4
D) 1. Hg(OAc)2, CH3OH / 2. NaBH4
E) NaOH, H2OAns: A
Topic: Predicting Addition ProductsSection: 9.12Difficulty Level: Easy
99. Which reaction is not stereospecific?
A) IB) IIC) IIID) IVE) VAns: C
Topic: Predicting Addition ProductsSection: 9.12Difficulty Level: Moderate
100. The expected product(s) resulting from addition of Br2 to (E)-3-hexene would be:A) a meso dibromide.B) a mixture of optically active enantiomeric dibromides.C) a mixture of optically inactive enantiomeric dibromides.D) (Z)-3,4-dibromo-3-hexene.E) (E)-3,4-dibromo-3-hexene.Ans: A
Topic: Predicting Addition ProductsSection: 9.12Difficulty Level: Moderate
101. Which of the following alkenes will yield a meso dihalide when reacted with Br2/CCl4 at room temperature?
A)
B)
C)
D)E) Both B and DAns: B
Topic: Predicting Addition ProductsSection: 9.12Difficulty Level: Moderate
102. What is the expected major product resulting from the acid-catalyzed hydration of 2,5-dimethyl-2-hexene?
A)
B)
C)
D)
E)Ans: B
Topic: Predicting Addition ProductsSection: 9.12Difficulty Level: Hard
103. What is the expected major product resulting from treatment of (E)-3-methyl-3-hexene with Br2 in the presence of methanol, CH3OH?
A)
B)
C)
D)E) All of the above are produced in equal amountsAns: A
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Easy
104. To accomplish a Markovnikov addition of water to an unsymmetrical alkene, with minimal skeletal rearrangement, the best reagents would be:
A) water and dilute acidB) water and concentrated acidC) 1. Hg(OAc)2, H2O 2. NaBH4, NaOH D) 1. BH3•THF 2. H2O2, NaOHE) 1. OsO4, pyridine 2. NaHSO3, H2OAns: C
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Easy
105. For the reaction sequence shown, what is the expected major elimination product?
A) IB) IIC) IIID) IVE) VAns: B
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Easy
106. For the reaction sequence shown, what is the expected major elimination product?
A) IB) IIC) IIID) IVE) VAns: D
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Easy
107. What is the expected major product of the following reaction sequence?
A) IB) IIC) IIID) IVE) VAns: C
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Moderate
108. What is the expected major product of the following reaction sequence?
A) IB) IIC) IIID) IVE) VAns: A
Topic: Synthetic Strategies, anti DihydroxylationSection: 9.13, 9.9Difficulty Level: Moderate
109. Which is the correct sequence of reaction steps necessary to complete the following transformation?
A) I then II then IIIB) II then I then IIIC) II then IVD) III then IE) I then IV then II then IIIAns: B
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Moderate
110. What is the expected major product of the following reaction sequence?
A) IB) IIC) IIID) IVE) VAns: C
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Moderate
111. What is the expected major product of the following reaction sequence?
A)
B)
C)
D)
E)Ans: A
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Moderate
112. What is the expected major product for the following reaction?
A)
B)
C)
D)
E)Ans: A
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Moderate
113. What is the expected major product of the following reaction sequence?
A)
B)
C)
D)
E)Ans: C
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Moderate
114. What is the expected major product of the following reaction sequence?
A)
B)
C)
D)
E)Ans: A
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Hard
115. What is the expected major product of the following reaction sequence?
A) IB) IIC) IIID) IVE) VAns: C
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Hard
116. For the following reaction sequence, which molecule is an expected major product?
A)
B)
C)
D)
E)
Ans: ATopic: Synthetic StrategiesSection: 9.13Difficulty Level: Hard
117. What is the expected major product of the following reaction sequence?
A)
B)
C)
D)
E)Ans: E
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Hard
118. For the following reaction sequence identify the expected major organic products and provide their stereochemical relationship.
A) I and II; enantiomersB) III and IV; enantiomersC) I and II; diastereomersD) II and III; diastereomersE) III and IV; diastereomersAns: D
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Hard
119. For the following reaction sequence identify the total number, frequency and types of stereoisomeric compounds expected as products.
A) 2 total stereoisomers; 1 set of enantiomersB) 4 total stereoisomers; 2 sets of enantiomersC) 4 total stereoisomers; 4 diastereoisomersD) 8 total stereoisomers; 4 sets of enantiomersE) 8 total stereoisomers; 8 diastereomersAns: E
Short Answer Questions:
Topic: Introduction to Addition ReactionsSection: 9.1Difficulty Level: Easy
120. bonds are quite susceptible to reaction with electron-seeking reagents, also referred to as ____________________.Ans: electrophiles
Topic: RegioselectivitySection: 9.3Difficulty Level: Easy
121. The rule that correctly predicts the regiochemistry of most ionic additions to alkenes is called ____________________.Ans: Markovnikov's Rule
Topic: HydrohalogenationSection: 9.3Difficulty Level: Easy
122. For the following reaction sequence provide the expected major organic product(s). Include all stereoisomers showing relevant stereochemistry.
Ans:
Topic: HydrohalogenationSection: 9.3Difficulty Level: Easy
123. Provide the structure(s) of the expected major organic product(s) generated upon completion of the following reaction scheme:
Ans:
Topic: Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Moderate
124. The reaction of HCl with 2-ethyl-1-pentene or HCl with 3-methyl-2-hexene results in the identical major product of 3-chloro-3-methylhexane. Provide a mechanistic scheme showing the reaction of each alkene with HCl, including the intermediate and product. Provide a brief explanation how the different alkene reactants were transformed into the same product.
Ans:
Electrophilic addition of a proton in the reaction between HCl and both alkenes will result in formation of the most stable intermediate carbocation. Addition of Cl– to the tertiary carbocation formed in both cases results in the observed product. The reason for the identical major product is a consequence of regioselective addition to the double bond forming the same tertiary carbocation intermediate.
Topic: Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Moderate
125. When the two constitutional isomers, 3,3-dimethyl-1-butene and 2,3-dimethyl-2-butene, are reacted with HCl the same major product is formed. Provide a mechanistic explanation for the observation.
Ans:
For the unsymmetrical 3,3-dimethyl-1-butene, the carbocation formed is 2°, but can readily undergo a methyl shift to form the more stable 3° carbocation, which is the same as that formed from 2,3-dimethyl-2-butene. The addition of the chloride ion to the carbocation forms the identical product, 2-chloro-2,3-dimethylbutane.
Topic: Hydrohalogenation and Carbocation RearrangementsSection: 9.3Difficulty Level: Moderate
126. Addition of HI to the alkene of the cyclobutane in the scheme below, results in a significant yield of the product shown. What other product(s) might also be obtained? Explain with a mechanism and brief discussion the observation of the given product as well as others that may arise.
Ans:Regioselective addition of the proton of HI generates a secondary carbocation. Rearrangement to a more stable 3o carbocation can occur by two alternative pathways (1 and 2). Pathway 1 results in relief of ring strain by expansion to a more stable 5-membered ring. The second pathway involving a methyl shift is less likely; ring strain is not relieved and becomes worse with incorporation of an sp2 carbon (bond angle 120°) into the cyclobutane (bond angle 90°). The third pathway occurs if addition of iodide to occurs before carbocation rearrangement. The first pathway is most likely, resulting in the observed product.
Topic: Acid-Catalyzed HydrationSection: 9.4Difficulty Level: Easy
127. For the following reaction sequence provide the expected major organic product(s). Include all stereoisomers showing relevant stereochemistry.
Ans:
Topic: Acid-Catalyzed HydrationSection: 9.4Difficulty Level: Easy
128. For the following reaction sequence provide the expected major organic product(s). Include all stereoisomers and clearly show relevant stereochemistry.
Ans:
Topic: Acid Catalyzed HydrationSection: 9.4Difficulty Level: Easy
129. Provide the structure(s) of the expected major organic product(s) generated upon completion of the following reaction scheme:
Ans:
Topic: Acid-Catalyzed HydrationSection: 9.4Difficulty Level: Moderate
130. The transformation shown below generates an achiral product from a chiral starting material. Provide the structure of the expected product and a mechanism explaining the transformation. Briefly explain why the product formed is achiral.
Ans:
Upon addition of the proton to the alkene a 2° carbocation is formed that undergoes a hydride shift to form a more stable 3° carbocation. The 3° carbocation is located in the center of the chain, and being sp2 hybridized is planar. Addition of water to the central carbon produces a product with no stereocenter and is thus achiral.
Topic: Hydroboration-OxidationSection: 9.6Difficulty Level: Easy
131. A reaction that could potentially yield two or more constitutional isomers, but as in hydroboration-oxidation produces only one isomer, is said to be _____________________.
Ans: regioselective
Topic: Hydroboration-OxidationSection: 9.6Difficulty Level: Easy
132. Any proper mechanism of hydroboration-oxidation must explain the observed _________ addition of the H and OH to the alkene as well as the _____________ regiochemistry.
Ans: syn, anti-Markovnikov
Topic: Hydroboration-OxidationSection: 9.6Difficulty Level: Easy
133. Provide the structure(s) of the expected major organic product(s) generated upon completion of the following reaction scheme:
Ans:
Topic: Halohydrin FormationSection: 9.8Difficulty Level: Easy
134. Provide the expected major organic product from the reaction shown below. Provide a brief explanation of any regioselectivity the reaction is expected to produce.
Ans:The alcohol will be found at the tertiary carbon, being the more substituted carbon. Initial formation of the bromonium ion will favor attack of the water at the more substituted carbon which is more capable of stabilizing the partial positive charge that develops in the transition state.
Topic: Halohydrin FormationSection: 9.8Difficulty Level: Moderate
135. For the following transformation below, provide a detailed step-wise mechanism showing the electron flow using the curved arrow formalism.
Ans:
Topic: Halohydrin FormationSection: 9.8Difficulty Level: Moderate
136. For the following reaction draw out the expected major organic product(s). Include regiochemical and/or stereochemical details as relevant, and provide a short justification for the product(s) drawn.
Ans:The reaction takes place with Markovnikov regioselectivity and anti stereospecificity, giving a racemic mixture of the halohydrin as the major product.
Topic: Halogenation and StereospecificitySection: 9.8Difficulty Level: Moderate
137. Draw Fischer projection formulas of the major product of the reaction between (E)-2-methyl-3-hexene and aqueous Br2.
Ans:
The reaction takes place with anti stereospecificity. Since the alkene is symmetrically substituted, Markovnikov rule is not applicable, and the reaction is not regioselective. The product mixture would therefore consist of 2 pairs of enantiomers, which are constitutional isomers of each other.
Topic: Oxidative CleavageSection: 9.11Difficulty Level: Easy
138. Provide the structure(s) of the expected major organic product(s) generated upon completion of the following reaction scheme:
Ans:
and
Topic: Predicting Reaction Products: Halohydrin Formation and StereospecificitySection: 9.12Difficulty Level: Moderate
139. Predict the structure(s) of the expected major organic product(s) of the following reaction. Include regiochemical and/or stereochemical details as needed.
Ans:The reaction takes place with Markovnikov regioselectivity and anti stereospecificity. As the product is chiral, the products are diastereomers.
Topic: Predicting Reaction Products: syn DihydroxylationSection: 9.12Difficulty Level: Moderate
140. Draw Fischer projection formula(s) of the major product(s) of the reaction between (Z)-2-methyl-3-hexene and cold, alkaline KMnO4.
Ans:The reaction takes place with syn stereospecificity, giving a racemic mixture of the diol product.
Topic: Predicting Reaction Products: syn DihydroxylationSection: 9.12Difficulty Level: Moderate
141. Draw Fischer projection formula(s) of the major product(s) of the reaction between (Z)-3-methyl-3-hexene and catalytic OsO4 NMO.
Ans:The reaction takes place with syn stereospecificity, giving a racemic mixture of the diol product.
Topic: Predicting Reaction Products: anti DihydroxylationSection: 9.12Difficulty Level: Moderate
142. Draw Fischer projection formula(s) of the major product(s) of the reaction between (Z)-3-methyl-3-hexene and MCPBA, followed by acidic water.
Ans:The reaction takes place with anti stereospecificity, giving a racemic mixture of the diol product.
Topic: Predicting Reaction Products: Oxidative CleavageSection: 9.12Difficulty Level: Moderate
143. Predict the product(s) of the oxidation of 2,3,4-trimethyl-1,5-heptadiene upon treatment with O3 followed by dimethylsulfide (DMS).
Ans:
Topic: Synthetic StrategiesSection: 9.14Difficulty Level: Moderate
144. A common problem in the acid catalyzed hydration of alkenes is the formation of an ether byproduct. Explain the formation of the ether byproduct in relation to the reaction below:
Ans:
Topic: Predicting Reaction Products: Halohydrin Formation and StereospecificitySection: 9.12Difficulty Level: Hard
145. Identify the structure(s) of the expected major organic product(s) of the following reaction. Draw the products in the expected chair conformations and include regiochemical and/or stereochemical details as needed.
Ans:
The reaction takes place with Markovnikov regioselectivity and anti stereospecificity. The starting material is shown as a single enatiomers, and thus produces two diastereomers. The product containing the cis fused rings is capable of a ring flip.
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Hard
146. Starting with (2R,3R)-2-chloro-3,4-dimethylpentane, a) draw the expected major product for each step, including regiochemical and stereochemical details when needed. In addition, b) briefly explain the mechanistic rational for each transformation.
i. t-BuOK/t-BuOH, heatii. MCPBA/CH2Cl2
iii. H3O+
Ans:
Hofmann elimination occurs upon heating with the bulky potassium tert-butoxide base, through an E2 elimination. Epoxidation with MCPBA is stereospecific (syn), giving a racemic (R,R & S,R) epoxide. Ring opening of the epoxide under acidic conditions is regio- and stereospecific.
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Hard
147. For the following transformation a) identify the starting material with correct stereochemistry and b) provide a complete reaction mechanism, including stereochemistry, to account for the product shown.
Ans:
Step 1 involves the epoxidation of the (E) alkene by MCPBA, showing only the enantiomer leading given product. Acid catalyzed ring opening of the epoxide would occur with regiospecific addition of MeOH to the 3° carbon. Deprotonation by a general base (likely MeOH in this example) provides the product, which upon bond rotation has the same conformation as the product given in the question.
Topic: Synthetic StrategiesSection: 9.13Difficulty Level: Hard
148. Consider the information given below and identify the structure of the unknown compound A, with a molecular formula of C8H14. Compound A reacts with Br2/CCl4. Upon reaction with excess H2/Ni 1-ethyl-2-methylcyclopentane is produced. Subjecting A to ozonolysis, the product shown below is produced as the major organic product. Draw the correct structure of compound A, and provide a brief and clear explanation relating the data provide with the structure selected.
Ans: A must be 3-ethyl-4-methylcyclopentene. This given data can be explained as shown below: