We describe the development of a scalable process for the "dark" singlet oxygenation of β-citronellol as a key step in the manufacture of the fragrance compound, rose oxide. This process, based on catalytic disproportionation of hydrogen peroxide into singlet oxygen and water, has been carried out on production scale in 10 m 3 reactors.

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Eleven W-based catalyst systems for alkene epoxidation with aqueous H2O2 were compared under identical conditions and at equal level of 0.1 mol % W-atoms. Of these, those based on a combination of H2WO4 and a methyltrioctylammonium phase transfer catalyst turned out to be most active in particular systems that contain a source of phosphate. Evidence is presented that under our conditions the actual epoxidizing species in H2WO4-based catalyst systems without phosphate source is mononuclear [WO(OH)(O2)2]- rather than binuclear [{WO(O2)2}2O]2- that is usually thought to be active. For large-scale applications, however, the polyoxometalate Na12[WZn3(ZnW9O34)2] (NaZnPOM) in combination with a suitable phase transfer catalyst such as methyltrioctylammonium chloride is preferred over H2WO4-based catalysts. This preference results from the fact that use of H2WO4 requires a catalyst activation step that is troublesome on a large scale, whereas epoxidations catalyzed by NaZnPOM start without induction period on addition of H2O2. Optimizations of epoxidations catalyzed by QCl/NaZnPOM or QCl/H2WO4 have shown that the optimum Q/W ratio depends on the alkene that is epoxidized and differs from that expected from catalyst stoichiometry. An attractive feature of NaZnPOM from the viewpoint of industrial applicability is that epoxidations and other reactions with H2O2 are efficiently catalyzed by a readily available aqueous solution of NaZnPOM prepared through self-assembly. A 1 mol scale example is provided of an epoxidation catalyzed by a combination of self-assembled NaZnPOM and Luviquat mono CP as a multifunctional cocatalyst with emulsifying, buffering, and phase-transferring properties.

Catalytic alkane functionalization continues to attract the attention of researchers.[1] Starting with the discovery of the platinum(ii)-catalyzed activation of unfunctionalized alkanes, [2] a variety of activating systems involving organometallic species [3, 4] have been developed. In addition numerous catalytic systems based on high-valent metal complexes, such as metal-oxo complexes, [1i, 5]