Oppenauer oxidation trichloroacetaldehyde

A modification of the Oppenauer oxidation which uses trichloroacetaldehyde on alumina provides a good, general oxidation of alcohols, and in particular will oxidize a secondary akdiol in the presence of a primary one, as shown by the examples given in Scheme 16. This method is claimed to be superiw to silver carbonate on Celite and much cheaper. Other advantages of this method are that it is neutral, nonaqueous, and halide, ester and lactone functionalities survive the reaction conditions. ... 

Chloral (trichloroacetaldehyde), CCI3CHO, oxidizes secondary alcohols to ketones in the presence of very active aluminum oxide (Woelm). This reaction seems to be superior to the Oppenauer oxidation, because it takes place at room temperature or at only slightly elevated temperatures [958, 959, 960],... 

Probably related mechanistically to the Oppenauer oxidations are several methods for oxidation that involve transfer of hydrogen to trichloroacetaldehyde. The reaction is mediated by alumina and is carried out by simply mixing the alcohol to be oxidized, the hydrogen acceptor, and alumina in an inert solvent. This reaction is suitable for selective oxidation of secondary alcohols in the presence of primary alcohols (which do not react) and also for the oxidation of compounds containing other easily oxidized functional groups. 

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