free radical substitutions

• What haloalkane is formed from methane and chlorine gas?

  Chloromethane
• What happens to a chloride ion when it loses an electron?

  It becomes a chloride radical
• How is a radical represented in chemical notation?

  By placing a dot next to it
• What are the three steps in free radical substitution?

  Initiation, propagation, termination
• What does initiation mean in the context of free radical substitution?

  Starting off the reaction
• What is the role of UV radiation in the initiation step?

  It provides energy to break bonds
• What is homolytic fission?

  Splitting where each atom gets one electron
• What do two chlorine radicals form during initiation?

  Two free radicals
• What happens during the propagation step?

  Radicals react to form new radicals
• What is formed when methane reacts with a chlorine radical?

  Chloromethane and a hydrogen radical
• What is the significance of the CH3 radical?

  It is highly reactive
• What happens when a CH3 radical reacts with Cl2?

  It forms chloromethane and a chlorine radical
• What is the purpose of the termination step?

  To stop the reaction and form stable products
• What is one way termination can occur?

  Two radicals combine to form a stable product
• What is a side reaction in the context of haloalkane synthesis?

  Formation of unintended products
• Why is free radical substitution not the best method for synthesizing haloalkanes?

  It can produce unwanted side products
• What are the steps involved in free radical substitution reactions?

  1. Initiation: Formation of radicals
  2. Propagation: Radicals react to form new radicals
  3. Termination: Radicals combine to form stable products
• What are the main reactions in the synthesis of haloalkanes?

  • Initiation: Cl2 → 2 Cl·
  • Propagation: CH4 + Cl· → CH3· + HCl
  • Propagation: CH3· + Cl2 → CH3Cl + Cl·
  • Termination: Cl· + Cl· → Cl2
  • Termination: CH3· + CH3· → C2H6
  • Termination: CH3· + Cl· → CH3Cl
• What are the characteristics of free radicals?

  • Highly reactive
  • Contain unpaired electrons
  • Form during initiation and propagation
• What are the limitations of using free radical substitution for haloalkane synthesis?

  • Unwanted side products formed
  • Reaction conditions can be difficult to control
  • Low selectivity for desired products