What exactly does the mechanism look like?

ByKokosminze

I can't imagine how that's supposed to work. And where does the Mn lone pair go after the syn addition?

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JenerDerBleibt
JenerDerBleibt
1 year ago

The fact that there is no precise mechanism is simply because there are several reaction paths that the permanganate can go and no one is really mechanistic enlightened as far as I know.

See that Mn goes from +7 to +4, but only 2 electrons are transmitted in the first step. There must be more than one "passage".

Just like you got this. If the H2O was added, the following would play: The H2 O cleaves in OH and H+. The OH forms one of the two hydroxyl groups on the ring. One of the O atoms of the permanganate then remains on the ring and forms the second hydroxyl group with the H+. A MnO3^. This could go through this cycle again and the MnO2 remains over at the end. That would be a conceivable mechanism. But no one writes that because no one knows exactly (sometimes 3 electrons have to pass over to the permanganate, but it is always only 2 of the alkene. Speak it in between also somehow further electrons are exchanged). Ergo remains with such a rough balance as you have it here.

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