Nanostructured Dioxomolybdenum(VI) Catalyst for the Liquid‐Phase Epoxidation of Olefins

Castro, Alichandra; Alonso, João C.; Valente, Anabela A.; Neves, Patrícia; Brandão, Paula; Félix, Vı́tor; Ferreira, Paula

doi:10.1002/ejic.200901093

Cited by 12 publications

(6 citation statements)

References 50 publications

(54 reference statements)

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“…Vanadium-based compounds are used as oxidation agents. The vanadium pentoxide has the highest oxidation state which makes it very important as catalysts in oxidation processes such as oxidation of SO 2 to SO 3 [18], xylene oxidation to phthalic anhydride [19] and furfural to maleic anhydride [20]. Similarly, some vanadyl complexes were synthesized and characterized for the application as insulin mimetic agents [21].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization of V2O5 nanoparticles and determination of catalase mimetic activity by new colorimetric method

Rasheed

Mansoor

Abdullah

et al. 2020

J Therm Anal Calorim

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This paper deals with an advanced colorimetric method used to determine the catalase mimetic activity of V2O5 nanoparticles by measuring the decrease in potassium permanganate concentration in a mixture containing V2O5 and hydrogen peroxide. The experiments were carried out in batch reactor at room temperature for 3 min at wavelength number of 525 nm. Vanadium pentoxide was synthesized by hydrothermal method (reflux) from ammonium metavanadate (NH4VO3) as a precursor and cetyltrimethylammonium bromide as a surfactant. The annealing of the product was carried out for 2 h, at temperatures of 250, 500 and 750 °C. In order to determine the structure and the chemical nature of the nanoparticles prepared, the characterization was carried out by X-ray diffraction and scanning electron microscopic techniques. Atomic force microscopic and thermal gravimetric investigations have shown the decomposition steps of V2O5 at different temperatures. UV–visible spectroscopic technique and Fourier transform spectrometry were used to further characterize the nanoparticles. Advanced colorimetric method was used to study the catalase mimetic activity of the newly synthesized vanadium pentoxide (V2O5) nanoparticles using hydrogen peroxide (H2O2) as substrate. V2O5 nanoparticles resulted in an increase in the catalase mimetic activity with increasing the annealing temperature of the V2O5 nanoparticles. The maximum activity was found at 500 °C, which subsequently decreased with further increase in the annealing temperature.

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Section: Introductionmentioning

confidence: 99%

Synthesis, characterization of V2O5 nanoparticles and determination of catalase mimetic activity by new colorimetric method

Rasheed

Mansoor

Abdullah

et al. 2020

J Therm Anal Calorim

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“…4 A range of other transition metal catalysts are active in this transformation, with molybdenum based complexes included amongst those showing high activities. 5 Oxomolybdenum catalysed epoxidations typically employ organohydroperoxide oxidants, most commonly tert-butylhydroperoxide (TBHP). 6 The substitution of the organohydroperoxide oxidants for more environmentally friendly oxidants such as molecular oxygen 7 or hydrogen peroxide 8,9 would be beneficial for obvious reasons.…”

Section: Introductionmentioning

confidence: 99%

New insights into the mechanism of oxodiperoxomolybdenum catalysed olefin epoxidation and the crystal structures of several oxo–peroxo molybdenum complexes

et al. 2012

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[Mo(O)(O(2))(2)(L)(2)] compounds (L = pz, pyrazole; dmpz, 3,5-dimethylpyrazole) were reacted stoichiometrically, in the absence of an oxidant, with cis-cyclooctene in an ionic liquid medium where selective formation of the corresponding epoxide was observed. However, this oxo-transfer reaction was not observed for some other olefins, suggesting that alternative reaction pathways exist for these epoxidation processes. Subsequently, DFT studies investigating the oxodiperoxomolybdenum catalysed epoxidation model reaction for ethylene with hydrogen peroxide oxidant were performed. The well known Sharpless mechanism was first analysed for the [Mo(O)(O(2))(2)(dmpz)(2)] model catalyst and a low energy reaction pathway was found, which fits well with the observed experimental results for cis-cyclooctene. The structural parameters of the computed dioxoperoxo intermediate [Mo(O)(2)(O(2))(dmpz)(2)] in the Sharpless mechanism compare well with those found for the same moiety within the [Mo(4)O(16)(dmpz)(6)] complex, for which the full X-ray report is presented here. A second mechanism for the model epoxidation reaction was theoretically investigated in order to clarify why some olefins, which do not react stoichiometrically in the absence of an oxidant, showed low level conversions in catalytic conditions. A Thiel-type mechanism, in which the oxidant activation occurs prior to the oxo-transfer step, was considered. The olefin attack of the hydroperoxide ligand formed upon activation of hydrogen peroxide with the [Mo(O)(O(2))(2)(dmpz)(2)] model catalyst was not possible to model. The presence of two dmpz ligands coordinated to the molybdenum centre prevented the olefin attack for steric reasons. However, a low energy reaction pathway was identified for the [Mo(O)(O(2))(2)(dmpz)] catalyst, which can be formed from [Mo(O)(2)(O(2))(dmpz)(2)] by ligand dissociation. Both mechanisms, Sharpless- and Thiel-type, were found to display comparable energy barriers and both are accessible alternative pathways in the oxodiperoxomolybdenum catalysed olefin epoxidation. Additionally, the molecular structures of [Mo(O)(O(2))(2)(H(2)O)(pz)] and [Hdmpz](4)[Mo(8)O(22)(O(2))(4)(dmpz)(2)]·2H(2)O and the full X-ray report of [Mo(O)(O(2))(2)(pz)(2)] are also presented.

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“…After 6 h of reaction, conversion of Lim was negligible for both MoO 3 and the heptamolybdate. When compared against previously investigated oxomolybdenum complexes or their carbonyl precursors tested as catalysts in the same reaction, using TBHP as an oxidant at 55 °C, the catalytic performance of complex 2 seems quite outstanding in terms of the LimOx yield reached (at 24 h, unless otherwise stated): [MoO 2 X 2 L 2 ] (for X = Cl, LimOx yields of 39% for L = dimethylformamide, 74% for L = {OP(CH 2 CH 3 )(Ph) 2 }, 65% for L 2 = bidentate salen ligand, 15–20% for L 2 = {PhCHNCH 2 CH 2 NCHPh}; for X = CH 3 , LimOx yield of 47% at 4 h for L 2 = N , N -p-tolyl-2,3-dimethyl-1,4-diazabutadiene); [MoO 2 L] where L is a tetradentate oxazoline ligand (59% LimOx yield) or a tetradentate salen ligand (50% LimOx yield); [CpMo(CO) n L] where n = 2 and L = η 3 -C 3 H 5 (70% of LimOx plus LimDiOx) or n = 3 and L = Cl (21% LimOx yield at 6 h); [Mo 2 O 4 (μ 2 -O)Cl 2 (pyrazole) 4 ] (59% LimOx yield at 6 h) . High LimOx yields have been reported in a few cases: 88% LimOx yield at 24 h/55 °C for [Mo(CO) 4 (ethyl[3-(2-pyridyl)-1-pyrazolyl]acetate}], 82% LimOx yield at 35 min for [(η 5 -C 9 H 7 )Mo(CO) 3 Me], and 95–100% LimOx yield at 24 h/55 °C for [MoO 2 X 2 L 2 ], where X = Cl or OSiPh 3 and L 2 = 2-(1-butyl-3-pyrazolyl)pyridine)…”

Section: Resultsmentioning

confidence: 99%

An Octanuclear Molybdenum(VI) Complex Containing Coordinatively Bound 4,4′-di-tert-Butyl-2,2′-Bipyridine, [Mo₈O₂₂(OH)₄(di-tBu-bipy)₄]: Synthesis, Structure, and Catalytic Epoxidation of Bio-Derived Olefins

Amarante

Neves

Tomé³

et al. 2012

Inorg. Chem.

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The reaction of [MoO(2)Cl(2)(di-tBu-bipy)] (1) (di-tBu-bipy = 4,4'-di-tert-butyl-2,2'-bipyridine) with water at 100-120 °C in a Teflon-lined stainless steel autoclave, in an open reflux system, or in a microwave synthesis system gave the octanuclear complex [Mo(8)O(22)(OH)(4)(di-tBu-bipy)(4)] (2) as a microcrystalline powder in good yields. Single crystals of 2 suitable for X-ray diffraction were obtained by the reaction of MoO(3) and di-tBu-bipy in water at 160 °C for 3 days. The molecular structure of 2 comprises a purely inorganic core, Mo(4)O(8)(μ(3)-OH)(2)(μ(2)-O)(2), attached to two peripheral oxo-bridged binuclear units, Mo(2)O(4)(μ(2)-O)(2)(OH)(di-tBu-bipy)(2). The inorganic core is composed of a unique assembly of four {MoO(5)} distorted square pyramids connected to each other via edge-sharing. Overall, the octanuclear complex adopts a highly distorted form strongly resembling an "S"-shaped molecular unit. Complex 2 was applied in the catalytic epoxidation of the biorenewable olefins DL-limonene (Lim) and methyl oleate (Ole), using tert-butylhydroperoxide (TBHP) as an oxygen donor, under mild reaction conditions (55 °C, air). The reactions of Lim and Ole gave the respective epoxide monomers in fairly high selectivities at high conversions (89% 1,2-epoxy-p-menth-8-ene selectivity at 96% Lim conversion; 99% methyl 9,10-epoxystearate selectivity at 94% Ole conversion, reached within 24 h reaction). Iodometric titrations revealed no measurable "non-productive" decomposition of TBHP.

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Nanostructured Dioxomolybdenum(VI) Catalyst for the Liquid‐Phase Epoxidation of Olefins

Cited by 12 publications

References 50 publications

Synthesis, characterization of V2O5 nanoparticles and determination of catalase mimetic activity by new colorimetric method

Synthesis, characterization of V2O5 nanoparticles and determination of catalase mimetic activity by new colorimetric method

New insights into the mechanism of oxodiperoxomolybdenum catalysed olefin epoxidation and the crystal structures of several oxo–peroxo molybdenum complexes

An Octanuclear Molybdenum(VI) Complex Containing Coordinatively Bound 4,4′-di-tert-Butyl-2,2′-Bipyridine, [Mo₈O₂₂(OH)₄(di-tBu-bipy)₄]: Synthesis, Structure, and Catalytic Epoxidation of Bio-Derived Olefins

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Nanostructured Dioxomolybdenum(VI) Catalyst for the Liquid‐Phase Epoxidation of Olefins

Cited by 12 publications

References 50 publications

Synthesis, characterization of V2O5 nanoparticles and determination of catalase mimetic activity by new colorimetric method

Synthesis, characterization of V2O5 nanoparticles and determination of catalase mimetic activity by new colorimetric method

New insights into the mechanism of oxodiperoxomolybdenum catalysed olefin epoxidation and the crystal structures of several oxo–peroxo molybdenum complexes

An Octanuclear Molybdenum(VI) Complex Containing Coordinatively Bound 4,4′-di-tert-Butyl-2,2′-Bipyridine, [Mo8O22(OH)4(di-tBu-bipy)4]: Synthesis, Structure, and Catalytic Epoxidation of Bio-Derived Olefins

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An Octanuclear Molybdenum(VI) Complex Containing Coordinatively Bound 4,4′-di-tert-Butyl-2,2′-Bipyridine, [Mo₈O₂₂(OH)₄(di-tBu-bipy)₄]: Synthesis, Structure, and Catalytic Epoxidation of Bio-Derived Olefins