有機(jī)合成氧化ppt課件-文庫(kù)吧資料
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【正文】 l moiety can be faster than the oxidation of alkene moiety. 。 and PCC or PDC give poor yields to some oxidation reactions (hindered alcohols). DMSO with mild base leads to removal of appropriate hydrogen and expulsion of DMS generates ketones and aldehydes from alcohols. Modification of DMSO oxidation: Swern oxidation Swern found that DMSO can be activated for the oxidation of alcohols by addition of trifluoroacetic anhydride. The reaction is usually done in dichloromethane at temperatures below 30℃ . Swern oxidation Swern also found that oxalyl chloride activates DMSO for the oxidation of alcohols and the resulting regent is superior to the DMSOtrifluoroacitic anhidride regent. Moffatt Oxidation Moffatt functionalized the DMSO with DCC in the present of an acids and a mild and efficient oxidizing regent for alcohols is formed. Example Other examples Example Other metal oxidants Tetropropylammonium perruthenateLey oxidation: a very mild oxidizing agent that is patible with many sensitive functional groups. Oppenauer oxidation Oppenauer used aluminum alkoxide to oxidize the alcohol to ketone. The character of this reaction is the reversibility. Side reaction: migration of a nonconjugated double bond into conjugation。 Oxidation with chronium (VI) Chromium trioxide in acetone: Jone’s Oxidation Acetone as a cosolvent Chromium trioxide Dilute sulfuric acid Example Chromium trioxidepyridine: Sarret oxidation Useful for the general oxidation of primary and secondary alcohols. Alkene, ketals and sulfide are oxidized much slower than alcohols. Drawback: Isolation of product from the pyridine solution is very difficult. Collins oxidation A modification of Sarret oxidation: the chromium trioxide – pyridine plex is first removed from the
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