Aerobic oxidation, alcohol catalysis

The complex Pd-(-)-sparteine was also used as catalyst in an important reaction. Two groups have simultaneously and independently reported a closely related aerobic oxidative kinetic resolution of secondary alcohols. The oxidation of secondary alcohols is one of the most common and well-studied reactions in chemistry. Although excellent catalytic enantioselective methods exist for a variety of oxidation processes, such as epoxidation, dihydroxy-lation, and aziridination, there are relatively few catalytic enantioselective examples of alcohol oxidation. The two research teams were interested in the metal-catalyzed aerobic oxidation of alcohols to aldehydes and ketones and became involved in extending the scopes of these oxidations to asymmetric catalysis. 

Other important successes have been achieved in developing clean, green, methods to oxidize alcohols, for example, the Ru/TEMPO (tetramethylpiperidiny-loxyl radical) catalysis, shown in Figure 9.4, for the aerobic oxidation of alcohols. ... 

We showed that the application of PEG/CO2 biphasic catalysis is also possible in aerobic oxidations of alcohols [15]. With regard to environmental aspects it is important to develop sustainable catalytic technologies for oxidations with molecular oxygen in fine chemicals synthesis, as conventional reactions often generate large amoimts of heavy metal and solvent waste. In the biphasic system, palladium nanoparticles can be used as catalysts for oxidation reactions because the PEG phase both stabilises the catalyst particles and enables product extraction with SCCO2. 

Chaudhuri, P., Hess, M., FTrke, U., and Wieghardt, K., 1998, From Structural Models of Galactose Oxidase to Homogeneous Catalysis Efficient Aerobic Oxidation of Alcohols, Angew. Chem., Int. Ed. Engl. 37 2217n2220. 

Tsunoyama H, Sakurai H, Tsukuda T (2006) Size effect on the catalysis of gold clusters dispersed in water for aerobic oxidation of alcohol. Chem Phys Lett 429 528 Pradhan N, Pal A, Pal T (2002) Silver nanoparticle catalyzed reduction of aromatic nitro compounds. Colloids Surf A 196 247... 

Oxidations Metal-catalyzed aerobic oxidation of organic compounds has been reviewed. Aerial oxidation of primary and secondary alcohols is mediated by TEMPO in the presence of HCl and NaN02- Secondary benzylic alcohols undergo aerial oxidation (or with r-BuOOH) based on catalysis by AuCl - neocuproine," but another report describes the oxidation of both primary and secondary alcohols (to acids and ketones, respectively) using nanoclusters of gold that are stabilized by poly(A-vinyl-2-pyrtolidone). ... 

As commented in the introduction the use of Gs in catalysis started about 2010 with the pioneering finding by Bielawski and co-workers who reported that GO, in the absence of any metal, is able to promote the aerobic oxidation of benzylic hydrocarbons [27]. Subsequently, graphite oxide was also found to be a carbocatalyst for this and other types of oxidations including also alcohol oxidation (Scheme 3.16). 

Wu, G. Wang, X. Guan, N. Li, L., Palladium on Graphene as Efficient Catalyst for Solvent-Free Aerobic Oxidation of Aromatic Alcohols Role of Graphene Support. Applied Catalysis B Environmental 2013,136-137,177-185. 

The catalytic aerobic oxidation of alcohols has a long history dating back to Dbbereiner s observation, in 1820, that ethanol is oxidized to acetic acid over platinum black. Indeed, this preceded the coining of the term catalysis, by Berzelius in 1835 The catalytic effect of platinum on the aerobic oxidation of cinnamyl alcohol was described by Strecker in 1855" and in the period 1912-1921 Wieland showed that finely divided palladium catalyzes the aerobic oxidation of primary alcohols to aldehydes in aqueous... 

Chromium(VI) catalyzes the oxidation of alcohols with alkyl hydroperoxides . Chromium-incorporated molecular sieves, in particular chromium-substituted aluminophosphate-5 (Cr-APO-5) were shown to be effective for the aerobic oxidation of secondary alcohols to the corresponding ketones (Reaction 19). This, and related catalysts, were first believed to be heterogeneous but more detailed investigations revealed that the observed catalysis is due to small amounts of soluble chromium that are leached from the framework by reaction with hydroperoxides. Reaction 19 may involve initial chromium-catalyzed free radical autoxidation of the alcohol to the a-hydroxyalkyl hydroperoxide followed by chromium-catalyzed oxygen transfer with the latter and/or H202 (formed by its dissociation) via an oxochromium(VI)-chromium(IV) cycle. 

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