Deck 10: Radical Reactions

Question 1

Rank the following radicals in order of decreasing stability (most stable to least stable).

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

Answer 1

II > I > III > IV

Question 2

Which term most accurately describes the process shown below?

A) coupling
B) elimination
C) halogen abstraction
D) hydrogen abstraction
E) homolytic cleavage

Answer 2

elimination

Question 3

Give the arrows to show the mechanism of the following radical process.

Answer 3

Question 4

In the molecule shown below, determine which of the highlighted C-H bonds (from a to e) is expected to have the lowest bond dissociation energy.

A) C-H_a
B) C-H_b
C) C-H_c
D) C-H_d
E) C-H_e

Question 5

Give the arrows to show the mechanism of the following radical process.

Question 6

Which of the following is an example of termination?

A) I
B) II
C) III
D) IV
E) none of the above

Question 7

Which term most accurately describes the process shown below?

A) hydrogen abstraction
B) halogen abstraction
C) homolytic cleavage
D) coupling
E) elimination

Question 8

Which of the following is the most stable radical?

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

Question 9

Give the arrows to show the mechanism of the following radical process.

Question 10

Give the arrows to show the mechanism of the following radical process.

Question 11

Identify an example of initiation.

A) homolytic cleavage
B) heterolytic cleavage
C) hydrogen abstraction
D) coupling
E) hydrogen addition

Question 12

Give arrows to show a homolytic bond cleavage of ethane to produce two methyl radicals.

Question 13

Which of the following is an example of initiation?

A) I
B) II
C) III
D) IV
E) none of the above

Question 14

Rank the following radicals in order of decreasing stability (most stable to least stable).

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

Question 15

Draw all of the reasonable resonance structures for the radical shown below.

Question 16

Which term most accurately describes the process shown below?

A) coupling
B) proton transfer
C) halogen abstraction
D) hydrogen abstraction E homolytic cleavage

Question 17

Which of the labeled C-H bonds is the weakest?

A) C-H_a
B) C-H_b
C) C-H_c
D) C-H_d
E) C-H_e

Question 18

Which of the following are the products of a homolytic cleavage of a C-C bond of ethane?

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

Question 19

Draw all of the reasonable resonance structures for the radical shown below.

Question 20

Which term most accurately describes the process shown below?

A) coupling
B) hydrogen abstraction
C) halogen abstraction
D) homolytic cleavage
E) addition to a π bond

Question 21

How many constitutional isomers are possible if propane is dichlorinated? Draw them.

Question 22

A bromine radical can add to the π bond of 2-methylpropene. Give the arrows to show this process and the expected result.

Question 23

Draw the arrows to show the propagation steps in the chlorination of propane to produce 2-chloropropane.

Question 24

Predict the major product of the following reaction.

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

Question 25

Which of the following represents a propagation step in the monochlorination of methylene chloride (CH₂Cl₂)?

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

Question 26

Which of the following correctly describes the nature of the transition state of the rate-determining step of the free-radical bromination of methane?

A) the transition state resembles the reactants more than the products
B) the transition state resembles the products more than the reactants
C) the transition state equally resembles products and reactants

Question 27

Which of the following processes is responsible for the fact that free radical bromination of methane is slower than free radical chlorination?

A) initiation
B) hydrogen abstraction
C) halogen abstraction
D) termination
E) entropy

Question 28

Which of the following are possible termination steps in the chlorination of methane?

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

Question 29

Which of the following shows the initiation step of monochlorination of methane?

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

Question 30

Predict the major product obtained upon radical bromination of t-butylcyclohexane.

A) 1-bromo-1-tert-butylcyclohexane
B) 2-bromo-1-tert-butylcyclohexane
C) 3-bromo-1-tert-butylcyclohexane
D) 4-bromo-1-tert-butylcyclohexane
E) 1-bromo-1,1-dimethylethylcyclohexane

Question 31

Free radical chlorination of ethane can produce higher halogenation products such as dichloroethane, trichloroethane, tetrachloroethane, pentachloroethane, and hexachloroethane. How could the production of higher halogenated products be minimized?

A) use an excess of chlorine
B) use an excess of ethane
C) use equimolar chlorine and ethane
D) it is not possible to minimize the production of higher halogenated products

Question 32

Identify an example of propagation.

A) homolytic cleavage
B) heterolytic cleavage
C) hydrogen abstraction
D) coupling
E) hydrogen addition

Question 33

Predict the major product(s) of the following reaction.

Question 34

Predict the major product(s) of the following reaction.

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

Question 35

Identify an example of termination.

A) homolytic cleavage
B) heterolytic cleavage
C) hydrogen abstraction
D) coupling
E) hydrogen addition

Question 36

Cyclic compound A has molecular formula C₅H₁₀ and undergoes monochlorination to yield exactly three different constitutional isomers. Identify compound A and show the monochlorination products.

Question 37

Both compounds A and B have molecular formula C₆H₁₄. Monochlorination of compound A results in the formation of two constitutional isomers. Monochlorination of compound B results in the formation of four constitutional isomers. Identify compounds A and B, and show the products of each monochlorination.

Question 38

Which of the following is most reactive towards chlorination?

A) methane
B) chloromethane
C) dichloromethane
D) chloroform
E) ethane

Question 39

Which of the following is the rate-determining step in the free-radical bromination of methane?

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

Question 40

Which of the following would you expect to function as an initiator at the lowest temperature?

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

Question 41

Upon treatment with NBS and irradiation with UV light, 2-methyl-2-butene reacts to produce exactly six monobrominated compounds. Draw the products of this reaction.

Question 42

Upon treatment with NBS and irradiation with UV light, 2-propyl-1-pentene produces exactly four monobrominated compounds (including stereoisomers). Draw and name the products of this reaction.

Question 43

Which of the following is the correct name for the major product of the following reaction?

A) (R)-3-bromo-3-ethylbutane
B) (S)-3-bromo-3-ethylbutane
C) (R)-3-bromo-3-methylpentane
D) (S)-3-bromo-3-methylpentane
E) 3-bromo-3-methylpentane

Question 44

What reagents would best accomplish the following synthesis?

A) Br₂
B) PBr₃
C) CH₃Br
D) NBS, heat

Question 45

Which of the following are possible product(s) of the reaction shown?

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

Question 46

Identify the likely major product(s) of the reaction shown.

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

Question 47

Compound A has molecular formula C₉H₂₀. Compound A produces exactly three constitutional isomers upon monochlorination, and one major constitutional isomer upon monobromination. Which of the following are possible structures of compound A?

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

Question 48

Predict the major product(s) of the following reaction.

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

Question 49

Draw the major product(s) of the following reaction. Is the product optically active? Explain.

Question 50

Predict the product(s) of the following reaction.

Question 51

Upon treatment with NBS and irradiation with UV light, 2-isopropyl-3-methyl-1-butene reacts to produce exactly two monobrominated compounds. Draw the products of this reaction.

Question 52

Draw the major product(s) of the following reaction. Is the product optically active? Explain.

Question 53

Which of the following compounds would be expected to be least destructive to the ozone layer?

A) CCl₃F
B) CCl₂F₂
C) CCl₂FCCl₂F
D) CF₃CH₂F

Question 54

Which of the following are major products of the reaction shown?

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

Question 55

Which of the following shows the correct products initially formed when ozone absorbs ultraviolet light?

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

Question 56

Compound A has molecular formula C₆H₁₂. Upon treatment with NBS and irradiation with UV light, exactly two compounds (including stereoisomers), are formed. Suggest a possible structure for compoundA.

Question 57

Predict the major product(s) of the following reaction.

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

Question 58

Draw all possible monochlorination products of 3,3-dimethylpentane, including stereoisomers.

Question 59

Upon treatment with NBS and irradiation with UV light, 1-ethyl-4-methylbenzene produces exactly three monobrominated compounds (including stereoisomers). Draw the products of this reaction.

Question 60

Upon treatment of 1-methylcyclopentene with NBS and irradiation with UV light, exactly nine compounds (including stereoisomers) are formed. Draw all nine products.

Question 61

Predict the product(s) of the following reaction.

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

Question 62

Give the arrows to show the second propagation step for the reaction of a chlorine radical with ozone.

Question 63

Predict the major product(s) of the reaction shown below.

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

Question 64

Which of the following steps is thermodynamically unfavorable at all temperatures?

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

Question 65

Predict the major product(s) of the reaction shown below.

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

Question 66

Identify the intermediate leads to the major product for the reaction of 2-methyl-2-butene with hydrogen bromide in the presence of peroxide.

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

Question 67

Of the four choices shown, which is likely to be a major product of the reaction below?

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

Question 68

Which of the following is expected to function as an antioxidant?

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

Question 69

Which of the following is the repeat unit for the polymer produced in the following reaction?

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

Question 70

Give the arrows to show the propagation steps for the following reaction.

Question 71

Which term best describes the process shown below?

A) neutralization
B) propagation
C) termination
D) initiation
E) elimination

Question 72

Of the four choices shown, which is likely to be a major product of the reaction below?

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

Question 73

Predict the product(s) of the following reaction.

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

Question 74

Which term best describes the process shown below?

A) neutralization
B) propagation
C) termination
D) initiation
E) elimination

Question 75

Identify the intermediate leads to the major product for the reaction of 2-methyl-2-butene with hydrogen bromide and hydrogen peroxide.

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

Question 76

Determine the repeat unit for the polymer produced in the following reaction.

A)
B)
C)
D)

Question 77

Give the arrows to show the propagation steps for the autooxidation of diethyl ether.

Question 78

Poly(methyl methacrylate) (PMMA) is a light, shatter-resistant plastic prepared by the free-radical polymerization of methyl methacrylate (shown below). What is the repeat unit of PMMA?

A)
B)
C)
D)

Question 79

Compound A, C₆H₁₂ reacts with HBr/ROOR to give compound B, C₆H₁₃Br. Compound C, C₆H₁₄, reacts with bromine and light to produce compound B, C₆H₁₃Br. Suggest structures for compounds A, B, and
C.

Question 80

Which of the following is expected to be a major product for the reaction shown below?

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