ORGANIC CHEMISTRY (LL)-PACKAGE
ORGANIC CHEMISTRY (LL)-PACKAGE
8th Edition
ISBN: 9781319316389
Author: VOLLHARDT
Publisher: MAC HIGHER
Question
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Chapter 4, Problem 54P

(a)

Interpretation Introduction

Interpretation: The mechanism for monochlorination with the help of iodobenzene dichloride should be proposed.

Concept introduction: The monochlorination performed with ultraviolet light proceeds via radical chain mechanism. Chlorine transforms CH4 into chloromethane as the major halogenated product with variety of side products due to various possibility of chain termination.

The mechanism for monochlorination comprises of three stages illustrated as follows:

Step1- Initiation via homolytic cleavage of ClCl bond: Cl2 initiates the reaction; undergoes homolysis to yield chlorine radicals. Energy for homolytic cleavage is provided by the heat or ultraviolet light.

  ORGANIC CHEMISTRY (LL)-PACKAGE, Chapter 4, Problem 54P , additional homework tip  1

Step2-: Propagation: In first of the propagation steps, Cl· radical generated from step 1 abstracts hydrogen radical from methane as follows:

  ORGANIC CHEMISTRY (LL)-PACKAGE, Chapter 4, Problem 54P , additional homework tip  2

In subsequent propagation step chloromethyl radical abstracts Cl· radical from another Cl2 , and liberates dichloromethane and new Cl· radical.

  ORGANIC CHEMISTRY (LL)-PACKAGE, Chapter 4, Problem 54P , additional homework tip  3

Step3: Termination: Radicals generated in propagation steps get quenched upon combination with one another. Thus termination steps are essentially the radical− radical combination illustrated as follows:

  ORGANIC CHEMISTRY (LL)-PACKAGE, Chapter 4, Problem 54P , additional homework tip  4

(b)

Interpretation Introduction

Interpretation: The three major sites of monochlorination present over steroidsshould be predicted.

Concept introduction: The monochlorination performed with ultraviolet light proceeds via radical chain mechanism. Chlorine transforms CH4 into chloromethane as the major halogenated product with variety of side products due to various possibility of chain termination.

The mechanism for monochlorination comprises of three stages illustrated as follows:

Initiation via homolytic cleavage of ClCl bond: Cl2 initiates the reaction; undergoes homolysis to yield chlorine radicals. Energy for homolytic cleavage is provided by the heat or ultraviolet light.

  ORGANIC CHEMISTRY (LL)-PACKAGE, Chapter 4, Problem 54P , additional homework tip  5

Step2-: Propagation: In first of the propagation steps Cl· radical generated from step 1 abstracts hydrogen radical from methane as follows:

  ORGANIC CHEMISTRY (LL)-PACKAGE, Chapter 4, Problem 54P , additional homework tip  6

In subsequent propagation step alkyl radical abstracts Cl· radical from another iodobenzene dichloride, and liberates dichloromethane and new Cl· radical.

  ORGANIC CHEMISTRY (LL)-PACKAGE, Chapter 4, Problem 54P , additional homework tip  7

Step3: Termination: Radicals generated in propagation steps get quenched upon combination with one another. Thus termination steps are essentially the radical− radical combination illustrated as follows:

  ORGANIC CHEMISTRY (LL)-PACKAGE, Chapter 4, Problem 54P , additional homework tip  8

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