Molybdenum-oxo chemistry in various aspects of oxygen atom transfer processes

Arzoumanian, Henri

doi:10.1016/s0010-8545(98)00056-3

Cited by 78 publications

(36 citation statements)

References 33 publications

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“…We have reported, over the years, the synthesis of several complexes bearing oxido, dioxido, µ-oxido, or peroxido ligands and studied, under homogeneous conditions, their properties as oxygen atom transfer agents with various O-donors. [32][33][34][35][36][37][38][39][40] Some aroused high interest, specially when found to be active with O 2 as the oxygen atom donor. Recently, we have significantly optimized the catalytic behavior of these systems by anchoring them covalently on the semiconductor solid matrix, anastase TiO 2 .…”

Section: Introductionmentioning

confidence: 99%

Silicon‐Assisted Direct Covalent Grafting on Metal Oxide Surfaces: Synthesis and Characterization of Carboxylate N,N′‐Ligands on TiO₂

et al. 2010

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The easy covalent bonding of an OH-bearing molecule onto a metal oxide surface can be done by transesterifying a trimethylsilylated hydroxy function with the surface OH groups. This results in the grafting of the organic molecule directly on the matrix, accompanied by the formation of trimethylsilanol, which can easily be eliminated as volatile hexamethyldisiloxane and water. This was accomplished on a TiO 2 matrix with three carboxylic acids: acetic, isonicotinic,

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Section: Introductionmentioning

confidence: 99%

Silicon‐Assisted Direct Covalent Grafting on Metal Oxide Surfaces: Synthesis and Characterization of Carboxylate N,N′‐Ligands on TiO₂

et al. 2010

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“…The oxygen isotopic labeling study presented indicates different characteristics of the TiO 2 photocatalytic mechanism compared to catalysis by noble or transition metal complexes. [33,34] Stuchinskaya et al studied the aerobic oxidation of alcohols to aldehydes and ketones on Ru-Co oxide catalyst, [35] and they concluded that this reaction system can be viewed as an oxidative dehydrogenation that does not affect the oxygen atom of an alcoholic group, whereas the formation of acids is an oxygenation; that is, it involves oxygen atom incorporation. Concerning the mechanism, the Ru-catalyzed oxidative dehydrogenation of alcohols is likely to occur via the formation of Ru IV alkoxide followed by b-elimination of Ru hydride species to yield the aldehyde or ketone, and subsequently catalyst regeneration by O 2 (Figure 2).…”

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confidence: 99%

Green Oxidation of Alcohols to Carbonyl Compounds by Heterogeneous Photocatalysis

Augugliaro

Palmisano

2010

ChemSusChem

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The selective conversion of alcohols to carbonyl compounds is essential for the preparation of fragrances, food additives, and many organic intermediates.[1] This transformation is carried out by catalytic processes that are of fundamental importance in synthetic chemistry.[2] Catalytic oxidation has long been carried out in environmentally harmful organic solvents (often chlorinated ones) at high temperatures and pressures by employing stoichiometric amounts of various inorganic oxidants, for example chromate and permanganate species, that play the role of oxygen donors. The latter oxidants are not only expensive and toxic but also produce large amounts of dangerous wastes, so that investigations have been concerned with substituting them for safer systems.In recent years, significant progress has been made in the development of effective catalytic processes for the aerobic oxidation of alcohols [3] with environmentally benign and inexpensive oxidants such as oxygen or air. Typically, the aerobic oxidation of alcohols involves the use of catalysts based on platinum-group metals and transition metal compounds. The latter are (1) transition metal complexes, which comprise a central metal atom and surrounding organic ligand(s); and (2) inorganic catalysts, mainly polyoxometalates [4,5] (POMs), typically oxides of molybdenum, tungsten, and vanadium. POMs are well-defined early transition metal-oxygen clusters with unique structural characteristics and catalytic properties. [6,7] Interestingly, many POMs share photochemical characteristics very similar to those of semiconductor photocatalysts, so that POMs represent the analogues of semiconductor metal oxides.[8] According to thermodynamics, an alcohol molecule with singlet electronic configuration cannot directly react with an unactivated dioxygen molecule, which has a triplet electronic configuration.[9] The working mechanism for all metal oxidation catalysts is that the metal atom mediates the electron transfer, and thereby induces the formation of singlet oxygen.In this respect, a wide range of homogeneous metal catalysts has been found capable to use molecular oxygen as the only oxidant. [10][11][12][13] For example, a water-soluble palladium(II) batho-phenanthroline complex has been used as catalyst at a pressure of 30 bar and a temperature of 373.16 K for the aerobic oxidation of a wide range of alcohols to aldehydes, ketones, and carboxylic acids in a biphasic water/alcohol system.[14] The alcohol conversion was almost complete and the yield of carbonyl compounds was in the range 79-90 %, depending on the substrate.The use of homogeneous catalysts, however, offers obvious disadvantages over heterogeneous systems with respect to ease of handling and catalyst recycling. A wide range of supported platinum and palladium catalysts has long been reported to exhibit high catalytic performance in the oxidation of alcohols.[15-17] Au/Pd-TiO 2 catalysts showing high turnover frequencies (up to 270 000 turnovers per hour) have been also proposed.[18] These catalysts, u...

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“…Dioxomolybdenum(VI) and tungsten(VI) complexes are known to catalyse oxotransfer reactions from DMSO to organic substrates or phosphines. [23,24,[27][28][29]38]. Generally, molybdenum-based catalysts are more active in these reactions than their tungsten counterparts.…”

Section: Scheme 2 Substrates For the Oxidation Reactionsmentioning

confidence: 99%

Dioxomolybdenum(VI) and -Tungsten(VI) Amino Bisphenolates as Epoxidation Catalysts

Peuronen

Lehtonen

2016

Top Catal

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Low-cost metallate salts Na2MO4·2H2O (M = molybdenum, tungsten) react with a tridentate amine bisphenol bis(2-hydroxy-3-tert-butyl-5-methylbenzyl)methylamine (H2ONO tBu ) under ambient conditions in acidic methanol solutions. The reactions lead to the formation of isostructural dioxo complexes [MO2(ONO tBu )(MeOH)]·MeOH in convenient yields. Spectral data as well as X-ray analyses reveal these complexes to be isostructural. Both compounds were tested as catalysts for epoxidation of olefins using ciscyclooctene, cyclohexene, norbornene and styrene as substrates and tert-butyl hydroperoxide and hydrogen peroxide as oxidants. The molybdenum complex catalyses selectively the oxidation of cis-cyclooctene and norbornene to corresponding epoxides, whereas oxidation of cyclohexene and styrene lead low yields as the epoxidations were associated with the formation of other oxidation products. Corresponding tungsten complex shows lower activity for epoxidation of norbornene and practically no activity for other olefins. Both complexes can also catalyse the conversion of benzoin to benzil using dimethyl sulphoxide as an oxidant, while the molybdenum complex shows higher activity.

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Molybdenum-oxo chemistry in various aspects of oxygen atom transfer processes

Cited by 78 publications

References 33 publications

Silicon‐Assisted Direct Covalent Grafting on Metal Oxide Surfaces: Synthesis and Characterization of Carboxylate N,N′‐Ligands on TiO₂

Silicon‐Assisted Direct Covalent Grafting on Metal Oxide Surfaces: Synthesis and Characterization of Carboxylate N,N′‐Ligands on TiO₂

Green Oxidation of Alcohols to Carbonyl Compounds by Heterogeneous Photocatalysis

Dioxomolybdenum(VI) and -Tungsten(VI) Amino Bisphenolates as Epoxidation Catalysts

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Molybdenum-oxo chemistry in various aspects of oxygen atom transfer processes

Cited by 78 publications

References 33 publications

Silicon‐Assisted Direct Covalent Grafting on Metal Oxide Surfaces: Synthesis and Characterization of Carboxylate N,N′‐Ligands on TiO2

Silicon‐Assisted Direct Covalent Grafting on Metal Oxide Surfaces: Synthesis and Characterization of Carboxylate N,N′‐Ligands on TiO2

Green Oxidation of Alcohols to Carbonyl Compounds by Heterogeneous Photocatalysis

Dioxomolybdenum(VI) and -Tungsten(VI) Amino Bisphenolates as Epoxidation Catalysts

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Silicon‐Assisted Direct Covalent Grafting on Metal Oxide Surfaces: Synthesis and Characterization of Carboxylate N,N′‐Ligands on TiO₂

Silicon‐Assisted Direct Covalent Grafting on Metal Oxide Surfaces: Synthesis and Characterization of Carboxylate N,N′‐Ligands on TiO₂