Master Organic Chemistry Reaction Guide

Oxidative Cleavage of Alkynes with Ozone (O3)

Description: Alkynes treated with ozone (O3) will be cleaved at the triple bond to form carboxylic acids. Terminal alkynes will give carbon dioxide (CO2)

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Comment section

14 thoughts on “Oxidative Cleavage of Alkynes with Ozone (O3)

    1. Sure thing! Imagine two six membered rings fused together. Now if at the ring fusion you had a double bond, ozonolyzis would cleave the double bond to give a 10 membered ring with two C=O groups.

  1. So ozonlysis of alkenes however with O3 produces not carboxylic acids but rather aldehydes or ketones. Why do not carboxylic acids form?

    1. Ozonolysis of alkYNES gives carboxylic acids, always.

      Ozonolysis of alkENES will give aldehydes /ketones if using a “reductive workup” e.g. Zn, Me2S
      Ozonolysis of alkenes will give carboxylic acids instead of aldehydes if using an “oxidative workup” e.g. H2O2

  2. you are saying that alkynes would always give carboxylic acids on ozonolysis but
    there is also a chance of formation of alkane with two keto or an acid anhydride….

    1. The one exception is that with terminal alkynes, formic acid is created, which is then oxidized to give carbon dioxide.

  3. In oxidative cleavage of alkyne mechanism, why -OH attached at R-C=O?
    I understand the -OH is from H2O.
    But I am difficult to understand why just -OH come out H2O.
    Plz teach me !! Help!!

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