Chapter 9
1. In an addition reaction to an alkene, the π bond plays the role of:
A) nucleophile
B) electrophile
C) leaving group
D) A and B
E) B and C
2. Addition reactions of alkenes are characterized by:
A) formation of a π bond
B) addition of two groups across a double bond
C) breaking of a π bond
D) A and B
E) B and C
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.
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.
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.
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.
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.
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).
10. The expected Markovnikov addition product of HI to 2-methyl-2-butene is:
A) 2-iodopentane
B) 2-iodo-2-methylbutane
C) 1-iodo-2-methylbutane
D) 2-iodo-1-methylbutane
E) 3-iodo-2-methylbutane
11. The regioselectivity and stereospecificity in hydrohalogenation of an alkene is best
described as:
A) Markovnikov orientation with syn-addition
B) Markovnikov orientation with anti-addition
C) anti-Markovnikov orientation with syn-addition
D) anti-Markovnikov orientation with anti-addition
E) Markonikov orientation with both syn- and anti-addition
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-methylbutane
B) 1-Chloro-3-methylbutane
C) 2-Chloro-2-methylbutane
D) 2-Chloro-3-methylbutane
E) 1-Chloropentane
31. The regioselectivity and stereospecificity in the acid-catalyzed hydration of an
alkene is best described as:
A) Markovnikov orientation with syn-addition
B) Markovnikov orientation with anti-addition
C) anti-Markovnikov orientation with syn-addition
D) anti-Markovnikov orientation with anti-addition
E) Markonikov orientation with both syn- and anti-addition
38. The regioselectivity and stereospecificity in the oxymercuration-demercuration of
an alkene is best described as:
A) Markovnikov orientation with syn-addition
B) Markovnikov orientation with anti-addition
C) anti-Markovnikov orientation with syn-addition
D) anti-Markovnikov orientation with anti-addition
E) Markonikov orientation with both syn- and anti-addition
40. What synthetic goal is achieved by subjecting an alkene to an oxymercuration-
demercuration reaction sequence?
A) Markovnikov addition of H2O, promoting skeletal rearrangement
B) Markovnikov addition of H2O, preventing skeletal rearrangement
C) anti-Markovnikov addition of H2O, promoting skeletal rearrangement
D) anti-Markovnikov addition of H2O, preventing skeletal rearrangement
E) anti-Markovnikov addition of H2O, syn-hydroxylation
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) ether
B) epoxide
C) alkane
D) syn diol
E) alkyne
45. The regioselectivity and stereospecificity in the hydroboration-oxidation of an
alkene is best described as:
A) Markovnikov orientation with syn-addition
B) Markovnikov orientation with anti-addition
C) Anti-Markovnikov orientation with syn-addition
D) Anti-Markovnikov orientation with anti-addition
E) Markovnikov orientation with both syn- and anti-addition
52. What is the expected major product for the hydrogenation of an alkene?
A) dihaloalkane
B) alkane
C) haloalkane
D) alcohol
E) ether
54. What product is formed when 5-chloro-1-methylcyclohexene is reduced with a Pt
catalyst and H2?
A) 1-chloro-5-methylcyclohexane
B) 1-chloro-3-methylcyclohexane
C) 5-chloro-1-methylcyclohexane
D) 3-chloro-1-methylcyclohexane
E) None of the above
55. What product is formed when trans-1,2-dimethylcyclohexane is reacted with Pd/C
and H2?
A) No reaction
B) cis-1,2-dimethylcyclohexane
C) trans-3,4-dimethylhexane
D) trans-1,2-dimethylhexane
E) None of the above
57. Which of the reagents below are expected to convert cyclopentene into
cyclopentane?
A) H2 and Ni
B) H2O
C) Heat
D) Zn, H3O+
E) Light
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) 2
C) 3
D) 4
E) None of the above
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) 1
C) 2
D) 3
E) 4
61. Which of the catalysts listed are used in the homogenous catalytic hydrogenation of
alkenes?
I) Ni II) Pt III) Wilkinson
A) I
B) II
C) III
D) I and II
E) II and III
62. In conducting a catalytic hydrogenation of an alkene, which catalyst listed is most
likely soluble in the reaction medium?
A) Ni
B) Pt
C) Pd
D) Wilkinson
E) All of the above are soluble
63. Wilkinson’s catalyst accomplishes which of the listed molecular transformations?
A) syn addition of H2 to an alkene
B) anti addition of H2 to an alkene
C) syn dihydroxylation of an alkene
D) anti dihydroxylation of an alkene
E) oxidative cleavage of an alkene
64. For the catalytic hydrogenation of alkenes, select from below those most likely to
function as a homogenous catalyst?
A) Wilkinson
B) Ni
C) Pd
D) Pt
E) Au
65. Which of the following will yield 2-methylpentane upon catalytic hydrogenation?
A) 2-methyl-1-pentene2
B) 2-methyl-2-pentene
C) 4-methyl-2-pentene
D) 4-methyl-1-pentene
E) All of the above
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) 1
B) 2
C) 3
D) 4
E) 5
70. What is the expected major product upon reaction of 1-pentene with Cl2?
A) 1-chloropentane
B) 2-chloropentane
C) 1,1-dichloropentane
D) 2,2-dichloropentane
E) 1,2-dichloropentane
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-methylpentane
B) 2,2-dibromo-2-methylpentane
C) 3,3-dibromo-2-methylpentane
D) 2-bromo-2-methylpentane
E) 3-dibromo-2-methylpentane
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.
87. Which of the following alkene addition reactions occur(s) specifically in syn
fashion?
A) dihydroxylation using OsO4, H2O2
B) addition of H2
C) hydroboration
D) addition of HCl
E) A, B, and C
95. Which of the following alkene addition reactions occur(s) specifically in an anti
fashion?
A) hydroboration-oxidation
B) addition of Br2
C) addition of H2
D) addition of H2O in dilute acid
E) both A and B
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 reasons
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.
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 acid
B) water and concentrated acid
C) 1. Hg(OAc)2, H2O 2. NaBH4, NaOH
D) 1. BH3•THF 2. H2O2, NaOH
E) 1. OsO4, pyridine 2. NaHSO3, H2O
Short Answer Questions:
Topic: Introduction to Addition Reactions
Section: 9.1
Difficulty Level: Easy
120. bonds are quite susceptible to reaction with electron-seeking reagents, also
referred to as ____________________.
121. The rule that correctly predicts the regiochemistry of most ionic additions to
alkenes is called ____________________.
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
_____________________.
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.