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Topic: Permanganate, Chromium Trioxide oxidation products  (Read 4643 times)

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Offline Dungsbars

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Permanganate, Chromium Trioxide oxidation products
« on: December 23, 2008, 11:44:59 AM »
I'm not sure whether this belongs here or in the organic forum. When I oxidize an alcohol or aldehyde with a strong oxidizing agent, like those in the topic title, I get a ketone/aldehyde or a carboxylic acid. But I wonder what happens with the oxidizing agents after this reaction.
When I write out the mechanism, I arrive at H3MnO4 or H2CrO3, which both don't seem to exist. They can dehydrate to HMnO3 and CrO2, of which the latter exists, but I'm not sure if that's what actually happens. And what happens with the "manganite" is a mystery.

Offline UnintentionalChaos

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Re: Permanganate, Chromium Trioxide oxidation products
« Reply #1 on: December 23, 2008, 03:03:36 PM »
Permanganate will be reduced all the way to Mn2+ in acid solution. In basic media, it precipitates as hydrated MnO2 when it hits the +4 oxidation state. Chromium trioxide/chromate/dichromate/PCC/PDC is reduced to Cr3+.

Offline Dungsbars

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Re: Permanganate, Chromium Trioxide oxidation products
« Reply #2 on: December 24, 2008, 05:09:52 PM »
But say we oxidize a secondary alcohol to a ketone. Carbon goes from 0 to +2, so you expect Mn7+ to go to Mn5+. How does it end up at 4+ or 2+? Same for Cr6+ going to Cr3+.

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