Master Organic Chemistry Reaction Guide

Free Radical Chlorination of Alkanes

Description: Alkanes treated with chlorine gas (Cl2) and light (hv) or heat will be converted into alkyl chlorides.

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Comment section

18 thoughts on “Free Radical Chlorination of Alkanes

  1. “…so the product mixture will be 3:1 favoring 1-chlorobutane over 2-chlorobutane.”
    Where is the example? Sorry, I do not see it as one of those. Did you mean Propane?

  2. In the mechanism picture where is states the bonds broken and formed, shouldn’t D be cl-cl broken and E be cl-c formed?

  3. chlorination of alkanes is an exothermic process , yet it requires high temperature or presence of sunlight .. what is it’s explanation..?

  4. Odd series of questions, but what would happen to other functional groups if I did this reaction? For instance, if I have but-2-ene or -yne and threw in Cl2 and light, would the Cls simply do chlorination of the alkene/yne? If I have a Carboxylic acid attached to a 3-carbon chain, would this result in the alpha hydrogen being replaced with a Cl?

  5. The relative rate of chlorination products is not only related to the number of primary, secondary, and tertiary hydrogens on each carbon, but also the tendency of radical formation at primary, secondary, and tertiary carbons. Relative rates of chlorination -> 5 at tertiary, 3.8 at secondary, 1 at primary. I just pulled those from memory, someone double check. Bromination is significantly more selective towards tertiary carbons. This is over simplified in your explanation.

    1. Thank you for adding this comment, you are correct that there are different selectivities of different types of C-H bonds.

  6. Thanks for the videos. Very helpful.

    In the second example you start with propane. The description of the mix of products that results refers to butane. Not a big deal though.

  7. James,

    I enjoyed the preacher voice and thought it was hilarious. An entire video in this voice would be funny, if you can sustain it. The real, absolute treasure of this and all of your videos, is the iron-clad stamina you grind out in carefully explaining each step for us. This commitment to clarity and simplicity is a driving sense of beauty so many of us appreciate but are just too busy to stop and thank you.

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