[superg]

Hi all,

i want to oxidize a secondary alcohol to form a ketone with MnO2. there is a paer describing this reaction, but i don't have acces to it. i've planned to do the reaction in DCM, with 1.5eq of MnO2 and just filter the reaction mixture throught celite once the reaction is finish... is it right?

do an of us have experience with this type of oxidizing agent?

thanks

[movies]

It usually takes a big excess of MnO₂ (like 5 equiv) and takes awhile.  Very clean reaction in my recollection though.  The quality of the MnO₂ is important to reactivity.

This oxidation doesn't work for just any secondary alcohol – it needs to be an activated one.

[OC pro]

I would recommend to use the "very active" MnO2...available from VWR/Merck. Or you simply do it yourself. Conc. HCl together with permanganate. But this is pain.
I always use 8equiv. of MnO2 in combination with refluxing dichloromethane. After complete conversion you filter through Celite. If the reaction slows down feel free to add more MnO2.

[408]

It is a nice oxidizing agent in terms of simple workup.  Can use massive excesses and it is easily removed.  Make sure to use the activated MnO2 though.

[superg]

thanks for replies,

is there any way to purify or activate the MnO2? i'll go for refluxing DCM and excess MnO2, and see how it goes...

[408]

You do not want calcined MnO2.  The best is to make it freshly precipitated. 

[discodermolide]

Hi all,

i want to oxidize a secondary alcohol to form a ketone with MnO2. there is a paer describing this reaction, but i don't have acces to it. i've planned to do the reaction in DCM, with 1.5eq of MnO2 and just filter the reaction mixture throught celite once the reaction is finish... is it right?

do an of us have experience with this type of oxidizing agent?

thanks

Have you been told to use MnO2? This would not be my choice, Iodobenzene diacetate, or better TEMPO/Bleach are more efficient.

[superg]

Hi,

i've run the reaction with 10eq of MnO2 in refluxing DCM, reaction complete in 3h. originally 5eq, after 2h he reaction seems to be slugglish, added 5 more equivalent, complete one hour later.

i oculd only use MnO2, other oxidizing agent could reaction negativelly with my substrate.

thanks for all info