Tetrabutylammonium Oxone

Tetrabutylammonium Oxone. This oxidant can be obtained as a white solid by reaction of commercial Oxone with Bu4NHS04. Unlike Oxone, which is soluble only in aqueous or alcoholic solvents, this salt is soluble in methylene chloride and CH3CN. 

E-Stilbene (0.181 g, 1 mmol) was dissolved in 1 2 acetonitrile DMM (15 mL). To this solution were added buffer (10 mL, 0.05 M solution of Na2B4O7l0H2O in 4 x 10-4 M aqueous Na2(EDTA)), tetrabutylammonium hydrogen sulfate (0.015 g, 0.04 mmol), and ketone catalyst (77.4 mg, 0.3 mmol). The mixture was cooled in an ice bath. A solution of Oxone (0.85 g, 1.38 mmol) in aqueous Na2(EDTA) (4 x 10-4 M, 6.5 mL) and a solution of K2CO3 (0.8 g, 5.8 mmol) in water (6.5 mL) were added dropwise separately over a period of 1.5 h (via syringe pumps or addition funnels). The best results were obtained if these solutions were added in a steady, uniform manner. After 2 h, the reaction was diluted with water (30 mL), and extracted with hexanes (4 x 40 mL). The combined extracts were washed with brine, dried (Na2S04), filtered, concentrated, and purified by FC on silica gel (previously buffered with 1% triethylamine solution in hexane) using 1 0 to 50 1 hexane ether as eluent. This provided trans-stilbene oxide (0.153 g, 78%) with 98.9% ee. 

Therefore, the classical rrani-dioxoRu(VI) - oxoRu(IV) catalytic cycle [2] (Fig. 1) can be ruled out as the primary reaction pathway in case of rapid catalytic oxygenation. The apparent zero-order kinetics observed are consistent with a steady-state catalytic regime accessible from different initial states of ruthenium metalloporphyrin. Indeed, common oxidants, other than aromatic iV-oxides, such as iodosylbenzene, magnesium monoperoxyphthalate, Oxone and tetrabutylammonium periodate produced the trans-dioxoRu(VI) species from Ru (TPFPP)(CO) under reaction conditions but were ineffective for the rapid catalysis. 

Another example of application of MW and ultrasound methods is the one-pot, tandem oxidation of cyclic alcohols to their respective lactones using KHSO5 (potassium peroxy-monosulfate) as oxidant and an IL as a solvent (Scheme 51). Ultrasound and MW irradiation reduced the reaction time for the cyclohexanol oxidation by Oxone , catalyzed by a TEMPO nitroxyl radical, in the presence of tetrabutylammonium bromide (TBAB) in [bmimjppj (bmim= l-butyl-3-methylimidazolium), from 8, using normal heating, to 5 and 0.5 h, respectively, with similar yields of ca. 80%. A new class of ILs with peroxymonosulphate anions was also synthesized and employed in the model oxidation. ... 

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