Solvent-free reactions using cetyltrimethylammonium permanganate and cetyltrimethylammonium dichromate-cis-1,2-dihydroxylation of alkenes, oxidation of alcohols and regeneration of aldehydes and ketones from oximes

Cetyltrimethylammonium permanganate (CTAP) and cetyltrimethylammonium dichromate (CTAD) have been known to be good oxidizing agents in organic solvent media. This homogeneous solution phase procedure itself is a useful advantage over oxidation reactions carried out employing inorganic manganese salts (e.g., KMnO4) or chromium salts (e.g., Kr2Cr2O7) performed under heterogeneous conditions. Now we have found that oxidation reactions using CTAP or CTAD do not require a solvent medium, and can be performed under completely solvent-free conditions. We have carried out 1,2-dihydroxylation of olefins with CTAP, oxidation of alcohols to aldehydes/ketones with CTAD, and regeneration of aldehydes and ketones from their oxime derivatives using either reagent, essentially under solid phase conditions. The results are excellent. As a dihydroxylating agent the CTAP is so good that it should be able to replace the highly toxic and expensive OsO4 for this reaction.