Oxidative Cleavage of Alkynes with Ozone (O3)

by James

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

Notes: The exact same reaction can be performed by KMnO4


Notes: For terminal alkynes (examples 1 and 4) the byproduct is carbon dioxide (CO2)

Mechanism: For the purposes of Org 1 / Org 2 the detailed mechanism is generally not considered to be “important”. However the mechanistic pathway is similar to that for the ozonolysis of alkenes.


{ 8 comments… read them below or add one }

Nate April 3, 2012 at 1:47 am

Can ozonolysis be used to cleave a double bond dividing a Bicyclic compound?


james April 3, 2012 at 12:41 pm

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.


Citrine April 16, 2012 at 4:09 pm

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


james April 17, 2012 at 10:38 pm

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


Raj October 18, 2012 at 2:47 am

I am guessing the mechanism is not as simple as with the alkenes


anonymous January 15, 2013 at 11:58 am

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….


james January 17, 2013 at 12:09 pm

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


Quinn Haynie March 20, 2013 at 9:32 pm

Carbonic acid does this, so formic acid does too?


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