SiliaCat TEMPO

More recently, a series of sol-gel hydrophobized nanostructured silica matrices doped with the organocatalyst TEMPO (SiliaCat TEMPO) entered the market as suitable oxidation catalysts for the rapid and selective production of carbonyls and carboxylic acids. In the former case, SiliaCat TEMPO selectively mediates the oxidation of delicate primary and secondary alcohol substrates into valued carbonyl derivatives (Scheme 5.2), retaining its potent activity throughout several reaction cycles (Table 5.2).33 Using this catalyst, for example, enables the synthesis of extremely valuable a-hydroxy acids with relevant selectivity enhancement by coupling of SiliaCat TEMPO with rapid Ru04-mediated olefin dihydroxylation (Scheme 5.3).34... 

Table 5.2 Activity of SiliaCat TEMPO in consecutive reaction cycles.

Human life, furthermore, certainly benefits from a less polluted world, and here, again, sol-gel entrapped catalysts are, literally, able to have transferred to within their large inner porosity the whole chemistry of fine chemicals production. Think for instance of an innocuous easily handled orange powder called SiliaCat TEMPO (Chapter 5) that added to a mixture of alcohols at 0 °C with a modest excess of aqueous, cold bleach rapidly converts them into all those fragrances, vitamins, hormones and drugs made of carbonyl compounds. 

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