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)
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{ 8 comments… read them below or add one }

Nate

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

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james

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.

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Citrine

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

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james

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

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Raj

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

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anonymous

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….
-_-||

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james

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

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Quinn Haynie

Carbonic acid does this, so formic acid does too?

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