We have demonstrated that a polyfluorinated alcohol, 2,2,2-trifluoroethanol, solvent enables haloperoxidase type activity and the oxychlorination of arenes (benzene and its alkylated derivatives) without a metal catalyst. The polyfluorinated alcohol has a dual function; it catalyzes electrophilic chlorination of less reactive arenes by several orders of magnitude and oxidation of chloride at lower H+ concentrations. DFT calculations show that a complementary charge template in the transition state explains the catalysis of the electrophilic chlorination.

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Nitrous oxide is usually considered to be inert 1 and a poor ligand toward transition metals. 2 However, there is incentive to use N 2 O as an oxygen donor because it contains 36 wt % oxygen, and the byproduct of an oxidation reaction would be N 2 . In practice, there are only a few catalytic systems that have been shown to be efficient for the activation of N 2 O for selective hydrocarbon oxidation. In the area of heterogeneous catalysis, the most effective catalysts appear to be iron-containing acidic zeolites 3 which at elevated temperatures are thought to yield surface activated iron-oxo species (R-oxygen), 4 which are capable of oxygen transfer to inert hydrocarbons. 5 Iron oxide on basic silica has been shown to catalyze, albeit nonselectively, propene epoxidation. 6 In some organometallic compounds, oxygen transfer from nitrous oxide to alkyl, alkyne, and imido ligands of transition metal complexes has been observed, 7 and metal-oxo species have been formed. 8 In addition, N 2 O has been decomposed at subambient temperatures to N 2 and O 2 by a ruthenium complex. 9 There is ongoing interest in oxidation catalyzed by polyoxometalates (POMs). 10 Here, we describe the activation of N 2 O by a Mn(III)-substituted polyoxometalate, Q 10 [Mn III 2 ZnW(ZnW 9 O 34 ) 2 ] (Q ) (C 8 H 17 ) 3 CH 3 N + ), Figure 1, and subsequent highly selective catalytic epoxidation of alkenes. Previously, it was shown that N 2 O reacts at room temperature with a ruthenium porphyrin 11 to give high valent ruthenium-dioxo species 12 capable of epoxidation of alkenes. Somewhat oddly, much more extreme conditions (140°C, 10 atm N 2 O) are necessary for homogeneous catalytic oxidation. 13 Epoxidation reactions of various alkenes catalyzed by Q 10 [Mn III 2 ZnW(ZnW 9 O 34 ) 2 ] 15 with N 2 O as oxygen donor were carried out in glass pressure tubes at 1 atm N 2 O and 150°C in fluorobenzene as solvent. The results presented in Table 1 show that epoxides were formed at very high selectivity (>99.9%). Typically, the reactions were rather slow, TOF ) 0.5-1.4 h -1 , 16 but proceeded in a linear fashion (Supporting Information), without indication of catalyst decomposition (IR). This is the first report of catalytic epoxidation with N 2 O with a Mn-based compound. There were only relatively small differences in the reactivity of the various alkenes; for example, the rather nucleophilic cyclooctene was only twice as reactive as less nucleophilic terminal alkenes such as 1-octene. Interestingly, trans-stilbene was slightly more reactive than cis-stilbene, and the reaction was stereoselective despite the rather high reaction temperatures. Cis-and trans-2-hexen-1-ol were similarly reactive. It is worthwhile to note that other transition-metal-substituted POMs of this structure were not active (V(IV), Co(II), Zn(II), Cu(II), Ni(II)) or were not selective (Fe(III) and Ru(III)) (Supporting Information). It is also crucial to note that among the Mn-substituted POMs only Mn(III) was active. No epoxidation was observed using similar Mn(II) POMs.An a p...

A series of transition metal substituted polyfluorooxometalates (PFOM) [M(L)H2F6NaW17)55]q-, M= Zn2+ , Co2+, Mn2+, Fc2+, Ru2+, Ni2+ and V5+ and L=H2O, O2-, of quasi-Wells-Dawson structure, was synthesized. In the series prepared, only the nickel-substituted polyfluorooxometalate was capable of catalytic activation of hydrogen peroxide in biphasic reaction media, the reaction leading mainly to the selective epoxidation of alkenes and alkenols. The manganese-, cobalt-, ruthenium-, iron-, vanadium-, and zinc-substituted polyfluorooxometalates were catalytically inactive, although, except for the zinc polyfluorooxometalate, very significant catalase activity was observed. Oxidation of thianthrene showed that sulfoxides were oxidized more easily than sulfides. Kinetic profiles of cyclooctene epoxidation showed that the reaction was zero order in both cyclooctene and hydrogen peroxide. Hydrogen peroxide was consumed at a rate 40% higher than the rate of epoxidation of cyclooctene. The reaction appears to proceed through an intermediate peroxo/hydroperoxo species that was observed in the IR spectrum. Atomic absorption, IR and 19F NMR spectroscopy indicated that the [Ni(H2O)H2F6NaW17O55]9- compound was stable under reaction conditions.

A vanadium‐substituted polyoxomolybdate ion ([PV2Mo10O40]5−, top right) can activate nitrous oxide to promote the highly selective catalytic oxidation of primary and secondary alcohols to aldehydes and ketones, and the oxidation of various alkylaromatic substrates (see scheme).