RE: ORGLIST: MnO2 as an oxidation reagent

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From: Jon Kremsky (jkremsky$##$primeorg.com)
Date: Mon Nov 22 2004 - 14:32:25 EST


The reagent is notoriously variable in quality. Years ago, Hercules made
the only reliable product.

It may be best to prepare the manganese dioxide from the reduction of
permanganate. See Fieser and Fieser V.1, p637, or Perrin.

Jon Kremsky
  -----Original Message-----
  From: everybody-bounces$##$orglist.net
[mailto:everybody-bounces$##$orglist.net]On Behalf Of Andy -
  Sent: Sunday, November 21, 2004 4:20 AM
  To: everybody$##$orglist.net
  Subject: ORGLIST: MnO2 as an oxidation reagent

  There are very mixed reviews of this reagent for oxidation of allylic
alcohols.

  This apparently stems from the "quality" of the MnO2 used, not the type of
solvent it is suspended in.,. (THF, DCM, CHCL3, and others)

  Is this in fact the case?

  Must the solvent be rigorously anhydrous?

  Could then MnO2 that was once considered "low-potency" be oven-dried
(powdered, etc, ) and then be used successfully in the same expiriment , in
effect, reserecting the oxidant?


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