Deck 11: Radical Reactions

Question 1

Use correct arrow formalism to show the following radical process:

Answer 1

Question 2

A bromine radical can add to the pi bond of 2-methylpropene.Use correct arrow formalism to show this process and the expected result.

Answer 2

Br adds to the least substituted end of the double bond because the resulting radical (3˚)is more stable than the alternative (1˚ if Br adds to the central C).

Question 3

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

Answer 3

hydrogen abstraction

Question 4

Using correct arrow formalism,draw all the resonance structures for the radical shown below.

Question 5

Free radical chlorination of ethane can produce higher halogenation products (dichlorinated,trichlorinated,etc…)in addition to chloroethane.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 6

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

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

Question 7

What term most accurately describes the process shown below?

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

Question 8

Use correct arrow formalism to show the following radical process:

Question 9

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 10

What term most accurately describes the process shown below?

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

Question 11

Use correct arrow formalism to draw all the resonance structure for the radical shown below.

Question 12

What term most accurately describes the process shown below?

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

Question 13

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

A)
B)
C)
D)

Question 14

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

Question 15

What term most accurately describes the process shown below?

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

Question 16

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

Question 17

Which of the following is most reactive towards chlorination?

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

Question 18

Use correct arrow formalism to show the propagation steps in the chlorination of propane to produce 2-chloropropane.

Question 19

Use correct arrow formalism to show the following radical process:

Question 20

Use correct arrow formalism to show the following radical process:

Question 21

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

Question 22

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 23

Predict the major product(s)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 24

Which term best describes the process shown below?

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

Question 25

The free radical polymerization of styrene with benzoyl peroxide yields a polymer that has repeat units arranged primarily in a 'head-to-tail' arrangement.This means that the phenyl group primarily ends up placed at alternating carbon atoms along the chain.Use correct arrow formalism to show why this arrangement is preferred over a 'head-to-head' or 'tail-to-tail' arrangement.

Question 26

Which 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 27

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

Question 28

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

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

Question 29

Use correct arrow formalism to show the second propagation step for the reaction of a chlorine radical with ozone.

Question 30

Compound A has molecular formula C₉H₂₀.Compound A produces three constitutional isomers upon chlorination,and one constitutional isomer upon bromination.Which of the following are possible structures of Compound A?

Question 31

Which of the following is/are expected to be the major product(s)for the reaction shown below?

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

Question 32

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

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

Question 33

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

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

Question 34

Use correct arrow formalism to show the propagation steps for the autooxidation of diethyl ether.

Question 35

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

Question 36

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

Question 37

Which term best describes the process shown below?

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

Question 38

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 39

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

Question 40

Which intermediate leads to the major product for the reaction of 2-methyl-2-butene with hydrogen bromide?

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

Question 41

Use correct arrow formalism to show termination by coupling of two growing poly(vinyl chloride)chains.

Question 42

Which monomer is used for the synthesis of Teflon?

A)1,1-difluoroethene
B)1,1,2,2-tetrafluoropropene
C)1,1,2,2-tetrafluoroethene
D)tetrafluoromethane

Question 43

Propose an efficient synthesis of 3,4-dimethyl-2-pentanol from 2-methyl-2-butene and ethanal.

Question 44

Propose an efficient synthesis of polyethylene from ethane.

Question 45

Propose an efficient synthesis of 2-methylpropene from 2-methylpropane.

Question 46

Your textbook mentions that the free radical polymerization of ethylene can produce branches.Although branches of various lengths are possible,butyl branches are very common.Suggest an explanation for this fact.

Question 47

Draw the product of coupling of the following radicals.

Question 48

One possible product of thermal cracking of hexane is 1-butene.Use correct arrow formalism to suggest a possible mechanism for this process starting from an alkyl radical.

Question 49

Thermal cracking of butane can produce ethyl radicals via homolytic cleavage.Use correct arrow formalism to show this process.

Question 50

Azobisisobutyronitrile (AIBN)is commonly used as a radical initiator.Use correct arrow formalism to show this process.

Question 51

Propose an efficient synthesis of 1-iodo-2-methylpropane from 2-methylpropene.

Question 52

Which monomer is used for the synthesis of poly(vinyl chloride)?

A)1-chloroethene
B)1-chloroethane
C)1,2-dichloroethene
D)1-chloro-1-propene