5.2.4

Chlorination

Test yourself

Chlorination

Chlorination is the first reaction mechanism that you need to learn. This mechanism involves free radicals.

Illustrative background for Overall reactionIllustrative background for Overall reaction ?? "content

Overall reaction

  • Products:
    • With excess methane, chloromethane.
    • With excess chlorine, you get multiple reactions and end up with tetrachloromethane.
  • The reaction can be split up into three stages:
    • Initiation.
    • Propagation.
    • Termination.
  • This is characteristic of all free radical reactions.
Illustrative background for InitiationIllustrative background for Initiation ?? "content

Initiation

  • This step first generates the free radicals.
  • The balanced equation is:
    • Cl2light2ClCl_2 \xrightarrow[\text{}]{\text{light}} 2Cl\bullet
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Propagation

  • There are often multiple propagation steps.
  • These involve a free radical, and generate a new free radical.
  • Relevant equations are:
    • CH4+ClCH3+HClCH_4 + Cl\bullet \rightarrow CH_3\bullet+ HCl
    • CH3+Cl2CH3Cl+ClCH_3\bullet + Cl_2 \rightarrow CH_3Cl + Cl\bullet
Illustrative background for TerminationIllustrative background for Termination ?? "content

Termination

  • A termination step is one which involves two free radicals forming a covalent bond.
    • It is said to ‘consume’ free radicals.
  • It is the final step in the reaction.
  • Relevant equations are:
    • 2CH3C2H62CH_3\bullet \rightarrow C_2H_6
    • 2ClCl22Cl\bullet \rightarrow Cl_2
    • CH3+ClCH3ClCH_3\bullet + Cl\bullet \rightarrow CH_3Cl

Jump to other topics

1Physical Chemistry

2Physical Chemistry 2 (A2 Only)

3Inorganic Chemistry

4Inorganic Chemistry 2 (A2 Only)

5Organic Chemistry 1

6Organic Chemistry 2 (A2 Only)

6.1Optical Isomerism (A2 Only)

6.2Aldehydes & Ketones (A2 Only)

6.3Carboxylic Acids & Esters (A2 Only)

6.4Aromatic Chemistry (A2 Only)

6.5Amines (A2 Only)

6.6Polymers (A2 Only)

6.7Biological Organic (A2 Only)

6.8Organic Synthesis (A2 Only)

6.9NMR Spectroscopy (A2 Only)

6.10Chromatography (A2 Only)

6.11A-A* (AO3/4) - Organic 2

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