Deck 8: Addition Reactions of Alkenes

Question 1

The alkene precursor to ethanol is __________.

Answer 1

ethylene or ethene

Question 2

Describe the regioselectivity and stereospecificity in the hydrohalogenation of an alkene.

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

Answer 2

Markovnikov orientation with both syn- and anti-addition

Question 3

What is a compound that does not have a double bond?

A) allicin (garlic)
B) geraniol (roses)
C) cholesterol
D) limonene (oranges)
E) ammonia

Answer 3

ammonia

Question 4

The decrease in entropy (the $\Delta$ S value is negative) observed for alkene addition reactions results from _______.

A) the breaking of a π and $\sigma$ bond.
B) the formation of two $\sigma$ bonds.
C) the reaction being exothermic.
D) two molecules reacting to form a single molecule.
E) the temperature dependence of the $\Delta$ S term.

Question 5

The alkene precursor to acetone is __________.

Question 6

For an addition reaction, why does free energy, $\Delta$ G, become more positive with increasing temperature?

A) The positive entropy dominates at high temperature.
B) The negative entropy dominates at high temperature.
C) The positive enthalpy dominates at high temperature.
D) The negative enthalpy dominates at high temperature.
E) The enthalpy and entropy cancel at high temperature.

Question 7

Identify the compound that does not come from an alkene.

A) acetic acid
B) methanol
C) isopropyl alcohol
D) acetone
E) ethylene glycol

Question 8

In an addition reaction to an alkene, the π bond is ______.

A) a nucleophile
B) an electrophile
C) a leaving group
D) A and B
E) B and C

Question 9

Which statement best describes the temperature dependence of an addition reaction?

A) Addition reactions are thermodynamically favored at all temperatures.
B) Addition reactions are thermodynamically disfavored at all temperatures.
C) Addition reactions are thermodynamically favored at low temperatures.
D) Addition reactions are thermodynamically favored at high temperatures.
E) Addition reactions are thermodynamically impossible.

Question 10

What is the expected major product of the following reaction?

A) I
B) II
C) III
D) IV
E) V

Question 11

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

Question 12

For this question, the "entropy term" refers to "-TΔS". Addition reactions are generally 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

Question 13

What compound is the expected product upon Markovnikov hydrohalogenation with HBr of the alkene shown below?

A) I
B) II
C) III
D) IV
E) V

Question 14

The rule that correctly predicts the regiochemistry of most ionic additions to alkenes is named after which chemist?

Question 15

Which of the structures shown depicts the most stable carbocation intermediate formed in the hydrohalogenation reaction shown?

A) I
B) II
C) III
D) IV
E) V

Question 16

Which of the molecules below would be the expected product for the hydrohalogenation of the following alkene with HBr?

A) I
B) II
C) III
D) IV
E) V

Question 17

Alkenes are found in ________, which are used by living organisms to trigger specific behavioral responses in other members of the same species.

Question 18

In the addition reaction of HI to 2-methyl-2-butene, what is the first step?

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)

Question 19

What is the expected Markovnikov addition product from the addition of HI to 2-methyl-2-butene?

A) 2-iodopentane
B) 2-iodo-2-methylbutane
C) 1-iodo-2-methylbutane
D) 1-iodo-3-methylbutane
E) 2-iodo-3-methylbutane

Question 20

Most π bonds are quite prone to reaction with an ____________________, also referred to as electron-seeking reagents.

Question 21

Which of the following carbocations is (are) likely to undergo rearrangement through a methyl shift?

A) I
B) II
C) III
D) I and II
E) II and III

Question 22

Which of the molecules below are enantiomers formed as products upon reaction of HBr with 4-methylpent-1-ene?

A) I and II
B) II and III
C) III and IV
D) I and III
E) II and IV

Question 23

What is the major product of the reaction below?

A) I
B) II
C) III
D) IV
E) V

Question 24

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 explanation showing the reaction of each alkene with HCl, including the intermediate and product. Provide a brief explanation of how the different alkene reactants could be transformed into the same product.

Question 25

What are the expected major product(s) of HBr addition to the alkene shown below?

A) I
B) II
C) III
D) IV
E) V

Question 26

For the following reaction sequence provide the expected major organic product(s). Include all stereoisomers showing relevant stereochemistry.

Question 27

Which of the molecules below arises from the anti-Markovnikov hydrohalogenation with HBr of the alkene shown?

A) I
B) II
C) III
D) IV
E) V

Question 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

Question 29

What is the major product for the following reaction?

A) I
B) II
C) III
D) IV
E) V

Question 30

Which of the alkenes shown below would produce a chirality center upon Markovnikov hydrohalogenation?

A) I
B) II
C) III
D) IV
E) V

Question 31

Identify the expected product(s) for the reaction shown below.

A) I
B) II
C) III
D) IV
E) V

Question 32

What is the expected major product(s) of HCl addition to the alkene below?

A) II
B) II and III
C) I and IV
D) V
E) I and II

Question 33

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 an explanation for the observation.

Question 34

What is the expected major product of the following reaction?

A) I
B) II
C) III
D) IV
E) V

Question 35

Which of the following carbocations is (are) likely to undergo rearrangement through a hydride shift?

A) I
B) II
C) III
D) I and II
E) II and III

Question 36

Which of the given reaction schemes would produce the molecule shown below?

A) I
B) II
C) III
D) Both I and II
E) Both II and III

Question 37

Provide the structure(s) of the expected major organic product(s) generated upon completion of the following reaction scheme:

Question 38

Which of the alkenes below would be expected to produce at least one chirality center upon hydrohalogenation in the presence of peroxide?

A) I
B) II
C) III
D) IV
E) V

Question 39

What is the expected major product for the following reaction?

A) I
B) II
C) III
D) IV
E) V

Question 40

Select the expected major product(s) of the following reaction.

A) I
B) II
C) III
D) I and II
E) I and III

Question 41

What is the expected major product for the following reaction?

A) I
B) II
C) III
D) IV
E) V

Question 42

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

Question 43

Which of the following is the major product of the reaction shown?

A) I
B) II
C) III
D) IV

Question 44

Identify the major product from the treatment of 1-methylcyclohexene with H₃O⁺.

A) I and III
B) II
C) III and V
D) IV
E) I, III and V

Question 45

Identify the description of the regioselectivity and stereospecificity in the acid-catalyzed hydration of an alkene.

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

Question 46

The three compounds below can form a carbocation under aqueous acidic conditions. Which ones will form the same carbocation?

A) I and II
B) I and III
C) II and III
D) All three will form the same carbocation

Question 47

Identify the compound that would react most rapidly with a dilute aqueous solution of H₂SO₄.

A) I
B) II
C) III
D) IV

Question 48

Give the expected major product of the following reaction.

A) I
B) II
C) III
D) IV
E) V

Question 49

Describe the products of the reaction below.

A) only one stereoisomer
B) an equal mixture of enantiomers
C) a roughly equal mixture of diasteromers
D) a roughly equal mixture of constitutional isomers

Question 50

Give the best description of the regioselectivity and stereospecificity in the oxymercuration of an alkene.

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

Question 51

Provide the structure(s) of the expected major organic product(s) generated upon completion of the following reaction scheme.

Question 52

The synthesis shown below generates an achiral product from a chiral starting material. Provide the structure of the expected product and a mechanism explaining the synthesis. Briefly explain why the product formed is achiral.

Question 53

Addition of HI to the alkene 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.

Question 54

Identify the expected major product of the following reaction.

A) I
B) II
C) III
D) IV
E) V

Question 55

For the following reaction sequence provide the expected major organic product(s). Include all stereoisomers showing relevant stereochemistry.

Question 56

For the following reaction sequence provide the expected major organic product(s). Include all stereoisomers and clearly show relevant stereochemistry.

Question 57

What would be the optimal conditions to effect the following synthesis?

A) dilute H₂SO₄
B) concentrated H₂SO₄
C) dilute HBr
D) concentrated HBr

Question 58

What would be the optimal conditions to effect the following synthesis?

A) dilute aqueous H₂SO₄
B) concentrated H₂SO₄
C) dilute aqueous HBr
D) concentrated HBr

Question 59

Identify the expected major product of the following reaction.

A) I
B) II
C) III
D) IV
E) V

Question 60

What is the expected major product for the following reaction?

A) I
B) II
C) III
D) IV
E) V

Question 61

What is the expected major product for the following reaction sequence?

A) I
B) II
C) III
D) IV
E) V

Question 62

Identify the product from the hydrogenation of an alkene.

A) dihaloalkane
B) alkane
C) haloalkane
D) alcohol
E) ether

Question 63

What reagents are needed to accomplish the following synthesis?

A) H₂O/H⁺
B) H₂O/Peroxide
C) OH^-
D) BH₃^.THF
E) 1. BH₃^.THF; 2. HO^-, H₂O₂, H₂O

Question 64

What is (are) the expected major product(s) for the following reaction sequence?

A) I
B) II
C) III
D) I and II
E) I and III

Question 65

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

Question 66

A reaction that could potentially yield two or more constitutional isomers, but as in hydroboration-oxidation produces only one isomer, is said to be _____________________.

Question 67

Provide the structure(s) of the expected major organic product(s) generated upon completion of the following reaction scheme.

Question 68

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

Question 69

What is the expected major product for the following reaction sequence?

A) I
B) II
C) III
D) IV
E) V

Question 70

What is the expected major product for the following reaction?

A) I
B) II
C) III
D) IV
E) V

Question 71

What is the expected major product for the following reaction sequence?

A) I
B) II
C) III
D) IV
E) V

Question 72

What is the expected major product for the following reaction?

A) I
B) II
C) III
D) IV
E) V

Question 73

Which of the following sets of reagents accomplishes the synthesis shown below?

A) H₂/HCl
B) H₂/H₂SO₄
C) H₂/Ni
D) H₂O/Ni
E) H₂O/H₂SO₄

Question 74

What is the expected major product for the following reaction?

A) I
B) II
C) III
D) IV
E) V

Question 75

Any proper mechanism of hydroboration-oxidation must explain the observed _________ addition of the H and OH to the alkene as well as the _____________ regiochemistry.

Question 76

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

Question 77

Give the best description for the regioselectivity and stereospecificity in the hydroboration-oxidation of an alkene.

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

Question 78

What is the expected major product for the following reaction sequence?

A) I
B) II
C) III
D) IV
E) V

Question 79

What is the name of the product formed when 5-chloro-1-methylcyclohexene is reduced with a Pt catalyst and H₂?

A) 1-chloro-2-methylcyclohexane
B) 1-chloro-3-methylcyclohexane
C) 1-chloro-5-methylcyclohexane
D) 3-chloro-1-methylcyclohexane
E) None of the above

Question 80

Provide the organic product(s) for the reaction shown below.

A) I
B) II
C) III
D) IV
E) V