Potential-energy versus reaction-coordinate diagrams for the two propagation steps in mechanism for monobromination of pentane should be sketched. Concept introduction: The mechanism for monobromination comprises of three stages illustrated as follows: Step1: Initiation via homolytic cleavage of Br − Br bond: Br 2 initiates the reaction; undergoes homolysis and forms bromine radical atom. Energy for homolytic cleavage is provided by the heat or ultraviolet light. Step2: Propagation: In first of the propagation steps bromine radical from step 1 abstracts hydrogen radical from methane as follows: In subsequent propagation step methyl radical abstracts Br · radical from another Br 2 , and liberates bromoethane and new bromine radical. Step3: Termination: Radicals generated in propagation steps get quenched upon combination with one another illustrated as follows:

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Answer 1

Question

Formula Formula Bond dissociation energy (BDE) is the energy required to break a bond, making it an endothermic process. BDE is calculated for a particular bond and therefore consists of fragments such as radicals since it undergoes homolytic bond cleavage. For the homolysis of a X-Y molecule, the energy of bond dissociation is calculated as the difference in the total enthalpy of formation for the reactants and products. X-Y → X + Y BDE = Δ H f X + Δ H f Y – Δ H f X-Y where, ΔHf is the heat of formation.

Chapter 3, Problem 32P

(a)

Interpretation Introduction

Interpretation: Potential-energy versus reaction-coordinate diagrams for the two propagation steps in mechanism for monobromination of pentane should be sketched.

Concept introduction: The mechanism for monobromination comprises of three stages illustrated as follows:

Step1: Initiation via homolytic cleavage of Br−Br bond: Br2 initiates the reaction; undergoes homolysis and forms bromine radical atom. Energy for homolytic cleavage is provided by the heat or ultraviolet light.

Step2: Propagation: In first of the propagation steps bromine radical from step 1 abstracts hydrogen radical from methane as follows:

In subsequent propagation step methyl radical abstracts Br· radical from another Br2 , and liberates bromoethane and new bromine radical.

Step3: Termination: Radicals generated in propagation steps get quenched upon combination with one another illustrated as follows:

(b)

Interpretation Introduction

Interpretation:The locations of the transition states and whether each transition state is early or late should be indicated.

Concept introduction:In general, the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition H is appreciably advanced when the transition state is reached.

(b)

Interpretation Introduction

Interpretation: The similar plot for reaction of pentane with I2 and difference from bromination plot should be indicated.

Concept introduction: In general the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition of H is appreciably advanced when the transition state is reached.

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Compound D, shown below, reacts with hydrogen bromide by electrophilic addition. A mixture of two organic compounds, E and F, is formed. CH3 CH₂CH₂ CH3 H compound D HBr Mixture of organic compounds E and F (i) Name the the two organic compounds E and F and show their condensed formula. (ii) Briefly explain the mechanism of the reaction between compound D and hydrogen bromide to form either compound E or compound F. (You can list/state the main steps) (iii) Which compound, E or F is the major product?

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Answer 2

Question

Formula Formula Bond dissociation energy (BDE) is the energy required to break a bond, making it an endothermic process. BDE is calculated for a particular bond and therefore consists of fragments such as radicals since it undergoes homolytic bond cleavage. For the homolysis of a X-Y molecule, the energy of bond dissociation is calculated as the difference in the total enthalpy of formation for the reactants and products. X-Y → X + Y BDE = Δ H f X + Δ H f Y – Δ H f X-Y where, ΔHf is the heat of formation.

Chapter 3, Problem 32P

(a)

Interpretation Introduction

Interpretation: Potential-energy versus reaction-coordinate diagrams for the two propagation steps in mechanism for monobromination of pentane should be sketched.

Concept introduction: The mechanism for monobromination comprises of three stages illustrated as follows:

Step1: Initiation via homolytic cleavage of Br−Br bond: Br2 initiates the reaction; undergoes homolysis and forms bromine radical atom. Energy for homolytic cleavage is provided by the heat or ultraviolet light.

Step2: Propagation: In first of the propagation steps bromine radical from step 1 abstracts hydrogen radical from methane as follows:

In subsequent propagation step methyl radical abstracts Br· radical from another Br2 , and liberates bromoethane and new bromine radical.

Step3: Termination: Radicals generated in propagation steps get quenched upon combination with one another illustrated as follows:

(b)

Interpretation Introduction

Interpretation:The locations of the transition states and whether each transition state is early or late should be indicated.

Concept introduction:In general, the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition H is appreciably advanced when the transition state is reached.

(b)

Interpretation Introduction

Interpretation: The similar plot for reaction of pentane with I2 and difference from bromination plot should be indicated.

Concept introduction: In general the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition of H is appreciably advanced when the transition state is reached.

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Answer 3

Question

Formula Formula Bond dissociation energy (BDE) is the energy required to break a bond, making it an endothermic process. BDE is calculated for a particular bond and therefore consists of fragments such as radicals since it undergoes homolytic bond cleavage. For the homolysis of a X-Y molecule, the energy of bond dissociation is calculated as the difference in the total enthalpy of formation for the reactants and products. X-Y → X + Y BDE = Δ H f X + Δ H f Y – Δ H f X-Y where, ΔHf is the heat of formation.

Chapter 3, Problem 32P

(a)

Interpretation Introduction

Interpretation: Potential-energy versus reaction-coordinate diagrams for the two propagation steps in mechanism for monobromination of pentane should be sketched.

Concept introduction: The mechanism for monobromination comprises of three stages illustrated as follows:

Step1: Initiation via homolytic cleavage of Br−Br bond: Br2 initiates the reaction; undergoes homolysis and forms bromine radical atom. Energy for homolytic cleavage is provided by the heat or ultraviolet light.

Step2: Propagation: In first of the propagation steps bromine radical from step 1 abstracts hydrogen radical from methane as follows:

In subsequent propagation step methyl radical abstracts Br· radical from another Br2 , and liberates bromoethane and new bromine radical.

Step3: Termination: Radicals generated in propagation steps get quenched upon combination with one another illustrated as follows:

(b)

Interpretation Introduction

Interpretation:The locations of the transition states and whether each transition state is early or late should be indicated.

Concept introduction:In general, the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition H is appreciably advanced when the transition state is reached.

(b)

Interpretation Introduction

Interpretation: The similar plot for reaction of pentane with I2 and difference from bromination plot should be indicated.

Concept introduction: In general the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition of H is appreciably advanced when the transition state is reached.

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Answer 4

Question

Formula Formula Bond dissociation energy (BDE) is the energy required to break a bond, making it an endothermic process. BDE is calculated for a particular bond and therefore consists of fragments such as radicals since it undergoes homolytic bond cleavage. For the homolysis of a X-Y molecule, the energy of bond dissociation is calculated as the difference in the total enthalpy of formation for the reactants and products. X-Y → X + Y BDE = Δ H f X + Δ H f Y – Δ H f X-Y where, ΔHf is the heat of formation.

Chapter 3, Problem 32P

(a)

Interpretation Introduction

Interpretation: Potential-energy versus reaction-coordinate diagrams for the two propagation steps in mechanism for monobromination of pentane should be sketched.

Concept introduction: The mechanism for monobromination comprises of three stages illustrated as follows:

Step1: Initiation via homolytic cleavage of Br−Br bond: Br2 initiates the reaction; undergoes homolysis and forms bromine radical atom. Energy for homolytic cleavage is provided by the heat or ultraviolet light.

Step2: Propagation: In first of the propagation steps bromine radical from step 1 abstracts hydrogen radical from methane as follows:

In subsequent propagation step methyl radical abstracts Br· radical from another Br2 , and liberates bromoethane and new bromine radical.

Step3: Termination: Radicals generated in propagation steps get quenched upon combination with one another illustrated as follows:

(b)

Interpretation Introduction

Interpretation:The locations of the transition states and whether each transition state is early or late should be indicated.

Concept introduction:In general, the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition H is appreciably advanced when the transition state is reached.

(b)

Interpretation Introduction

Interpretation: The similar plot for reaction of pentane with I2 and difference from bromination plot should be indicated.

Concept introduction: In general the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition of H is appreciably advanced when the transition state is reached.

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Answer 5

Chapter 3, Problem 32P

(a)

Interpretation Introduction

Interpretation: Potential-energy versus reaction-coordinate diagrams for the two propagation steps in mechanism for monobromination of pentane should be sketched.

Concept introduction: The mechanism for monobromination comprises of three stages illustrated as follows:

Step1: Initiation via homolytic cleavage of Br−Br bond: Br2 initiates the reaction; undergoes homolysis and forms bromine radical atom. Energy for homolytic cleavage is provided by the heat or ultraviolet light.

Step2: Propagation: In first of the propagation steps bromine radical from step 1 abstracts hydrogen radical from methane as follows:

In subsequent propagation step methyl radical abstracts Br· radical from another Br2 , and liberates bromoethane and new bromine radical.

Step3: Termination: Radicals generated in propagation steps get quenched upon combination with one another illustrated as follows:

(b)

Interpretation Introduction

Interpretation:The locations of the transition states and whether each transition state is early or late should be indicated.

Concept introduction:In general, the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition H is appreciably advanced when the transition state is reached.

(b)

Interpretation Introduction

Interpretation: The similar plot for reaction of pentane with I2 and difference from bromination plot should be indicated.

Concept introduction: In general the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition of H is appreciably advanced when the transition state is reached.

Answer 6

Chapter 3, Problem 32P

(a)

Interpretation Introduction

Interpretation: Potential-energy versus reaction-coordinate diagrams for the two propagation steps in mechanism for monobromination of pentane should be sketched.

Concept introduction: The mechanism for monobromination comprises of three stages illustrated as follows:

Step1: Initiation via homolytic cleavage of Br−Br bond: Br2 initiates the reaction; undergoes homolysis and forms bromine radical atom. Energy for homolytic cleavage is provided by the heat or ultraviolet light.

Step2: Propagation: In first of the propagation steps bromine radical from step 1 abstracts hydrogen radical from methane as follows:

In subsequent propagation step methyl radical abstracts Br· radical from another Br2 , and liberates bromoethane and new bromine radical.

Step3: Termination: Radicals generated in propagation steps get quenched upon combination with one another illustrated as follows:

Answer 7

Chapter 3, Problem 32P

(a)

Interpretation Introduction

Interpretation: Potential-energy versus reaction-coordinate diagrams for the two propagation steps in mechanism for monobromination of pentane should be sketched.

Concept introduction: The mechanism for monobromination comprises of three stages illustrated as follows:

Step1: Initiation via homolytic cleavage of Br−Br bond: Br2 initiates the reaction; undergoes homolysis and forms bromine radical atom. Energy for homolytic cleavage is provided by the heat or ultraviolet light.

Step2: Propagation: In first of the propagation steps bromine radical from step 1 abstracts hydrogen radical from methane as follows:

In subsequent propagation step methyl radical abstracts Br· radical from another Br2 , and liberates bromoethane and new bromine radical.

Step3: Termination: Radicals generated in propagation steps get quenched upon combination with one another illustrated as follows:

Answer 8

(b)

Interpretation Introduction

Interpretation:The locations of the transition states and whether each transition state is early or late should be indicated.

Concept introduction:In general, the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition H is appreciably advanced when the transition state is reached.

Answer 9

(b)

Interpretation Introduction

Interpretation:The locations of the transition states and whether each transition state is early or late should be indicated.

Concept introduction:In general, the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition H is appreciably advanced when the transition state is reached.

Answer 10

(b)

Interpretation Introduction

Interpretation: The similar plot for reaction of pentane with I2 and difference from bromination plot should be indicated.

Concept introduction: In general the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition of H is appreciably advanced when the transition state is reached.

Answer 11

(b)

Interpretation Introduction

Interpretation: The similar plot for reaction of pentane with I2 and difference from bromination plot should be indicated.

Concept introduction: In general the exothermic reactions are characterized by an early transition state while the endothermic reaction is characterized by a late transition state.

In the former case, the transfer of H is not very advanced while in latter transition of H is appreciably advanced when the transition state is reached.

Answer 12

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Answer 13

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Answer 14

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Answer 15

Ch. 3.1 - Prob. 3.2TIY Ch. 3.1 - Prob. 3.3E Ch. 3.4 - Prob. 3.5TIY Ch. 3.5 - Prob. 3.6E Ch. 3.7 - Prob. 3.7E Ch. 3.7 - Prob. 3.9TIY Ch. 3.9 - Prob. 3.11TIY Ch. 3.11 - Prob. 3.12E Ch. 3 - Prob. 15P Ch. 3 - Prob. 16P

Solution Summary: The author illustrates the potential-energy versus reaction-coordinate diagrams for the two propagation steps in mechanism for monobromination of pentane.

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