Lecture Notes: Hydrocarbons and Haloalkanes

Introduction

• Preface: Discussion on the process of synthesizing haloalkanes from hydrocarbons.
• Connection to Previous Lecture: Preparation from alcohols was completed. Now focusing on hydrocarbons.

Hydrocarbons to Haloalkanes

• Free Radical Mechanism:
  • The process involves 3 steps:
    1. Chain Initiation: Formation of free radicals.
    2. Chain Propagation: Free radicals react with each other.
    3. Chain Termination: The process ends.
• Example: Reaction between CH4 (methane) and chlorine.

Details of Chain Steps

1. Chain Initiation

• Homolytic fission of chlorine (Cl2).
• Formation of free radicals.

2. Chain Propagation

• Meeting of free radicals of chlorine and hydrogen.
• Free radicals combine to form new compounds.

3. Chain Termination

• When free radicals meet and form products.
• Haloalkane is obtained after the process ends.

From Alkene to Haloalkane

• Addition of Halogen Acid:
  • Two types:
    • Symmetrical Alkene: Carbon atoms are the same on both sides.
    • Unsymmetrical Alkene: Carbon atoms are different on both sides.
• Markovnikov’s Rule:
  • Preference is given to the richer (hydrogen) carbon.
• Anti-Markovnikov's Rule:
  • In some special circumstances, the opposite occurs, minor becomes major.

Conclusion

• Key Points:
  • Markovnikov’s Rule: Poor gets richer.
  • Anti-Markovnikov's Rule: Rich gets poorer.

Suggestions

• Keep the summary of the lecture in notes and practice.
• Wait for the next lecture where more information will be provided.