A functionalized polyoxometalate solid for selective oxidation of styrene to benzaldehyde

Tang, Jing; Yang, Xiuli; Zhang, Xian Wei; Wang, Miao; Wu, Chuan De

doi:10.1039/b924041a

Cited by 35 publications

(21 citation statements)

References 28 publications

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“…70 The oxidation of styrene to benzaldehyde with H 2 O 2 catalyzed by polyoxotungstates and peroxophosphotungstates is already well documented in the literature. 33,[71][72][73] The mechanism proceeds initially by the interaction of H 2 O 2 with the POM, generating active species which may be hydroperoxo or bridging peroxo species. Afterwards, styrene is bonded with one of the metal-peroxo bonds to produce a peroxometallocycle and in the next step styrene oxide is formed.…”

Section: Homogeneous Catalysismentioning

confidence: 99%

Mono-substituted silicotungstates as active catalysts for sustainable oxidations: homo- and heterogeneous performance

et al. 2013

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A series of tetrabutylammonium (TBA) salts of the transition metal mono-substituted silicotungstates [SiW 11 M(H 2 O)O 39 ] nÀ , M = Co II , Fe III , Mn III , (SiW 11 M) were explored as homogeneous catalysts for the oxidation of geraniol and styrene with H 2 O 2 . The most active homogeneous catalysts (SiW 11 Co and SiW 11 Fe) were immobilized onto an amine-functionalized SBA-15 (aptesSBA-15) and the resulting composites were characterized using several techniques (FT-IR, FT-Raman, UV-Vis/DRS, elemental analysis, powder XRD, SEM and N 2 adsorption-desorption isotherms). The catalytic performance of the new composites SiW 11 Co@aptesSBA-15 and SiW 11 Fe@aptesSBA-15 was investigated under similar experimental conditions to those used for homogeneous counterparts. 2,3-Epoxygeraniol and benzaldehyde were the main products obtained from geraniol and styrene oxidation, respectively, for all the catalysts. SiW 11 Co and SiW 11 Co@aptesSBA-15 showed to be the most active catalysts for the oxidation of geraniol and styrene.The recyclability of the composite SiW 11 Co@aptesSBA-15 was investigated for three reaction cycles. The stability of the composites was confirmed using several techniques after catalytic cycles.

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Section: Homogeneous Catalysismentioning

confidence: 99%

Mono-substituted silicotungstates as active catalysts for sustainable oxidations: homo- and heterogeneous performance

et al. 2013

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“…The aerobic oxidation of styrene using Co(III) catalysts has been reported previously,31–38 A redox active Co(II) has been reported to be able to a 96% conversion of styrene to benzaldehyde 33, 34. The efficiency of the reaction is increased by lowering the temperature and is optimum with low oxygen pressures 34–38.…”

Section: Resultsmentioning

confidence: 80%

Microstructure and biocompatibility of composite biomaterials fabricated from titanium and tricalcium phosphate by spark plasma sintering

Mondal

Linh

et al. 2012

J Biomedical Materials Res

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Important issues in developing hydroxyapatite (HAp)- and titanium (Ti)-based composite biomaterials for orthopedic or dental devices include the dissociation of HAp during fabrication and its influences in the microstructure and biocompatibility of the final composite. During the densification by sintering of HAp/Ti composites, Ti reacts with -OH freed from HAp to form TiO2 thus dissociated HAp into Ca3(PO4)2, CaO, CaTiO3, TiP, and so forth. To inhibit this reaction, composites were fabricated with Ti and 30, 50, and 70 vol % β-tricalcium phosphate (β-TCP) instead of HAp by spark plasma sintering at 1200°C. It has been observed that after sintering at 1200°C, Ti also reacted with TCP, but unlike HAp/Ti composites, the final TCP/Ti composites contained significant amounts of unreacted TCP and Ti phases. The initial 70 vol % TCP/Ti composite showed compressive strength of 388.5 MPa, Young's modulus of 3.23 GPa, and Vickers hardness of 361.9 HV after sintering. The in vitro cytotoxicity and proliferation of osteoblast cells on the composites surfaces showed that the addition of a higher amount of TCP with Ti was beneficial by increasing cell viability, cell-composite attachment and proliferation. Osteopontin and collagen type II protein expression from osteoblasts cultured onto the 70% TCP-Ti composite was also higher than other composites and pure Ti. In vivo study verified that within 3 months of implantation in an animal body, 70% TCP-Ti had an excellent bone-implant interface compared with a pure Ti metal implant.

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“…Similar experiments have been conducted with other peroxides and the inhibition effect appears to be essentially independent of the peroxide, although the efficiency of creation of the aldehyde depends on the ease with which the peroxide can interact with the cobalt salt. The aerobic oxidation of styrene using Co(III) catalysts has been reported previously, [31][32][33][34][35][36][37][38] A redox active Co(II) has been reported to be able to a 96% conversion of styrene to benzaldehyde. 33,34 The efficiency of the reaction is increased by lowering the temperature and is optimum with low oxygen pressures.…”

Section: Inhibition Of the Reaction By Oxygenmentioning

confidence: 99%

“…The aerobic oxidation of styrene using Co(III) catalysts has been reported previously, [31][32][33][34][35][36][37][38] A redox active Co(II) has been reported to be able to a 96% conversion of styrene to benzaldehyde. 33,34 The efficiency of the reaction is increased by lowering the temperature and is optimum with low oxygen pressures. [34][35][36][37][38] At high concentrations the benzaldehyde can bind to the cobalt complex and block further reaction.…”

Section: Inhibition Of the Reaction By Oxygenmentioning

confidence: 99%

Redox initiated free radical polymerization of 4‐methylstyrene

Mortamet

Pethrick

2011

J of Applied Polymer Sci

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Studies of the thermally initiated polymerization of 4-methylstyrene using alkylperoxide in conjunction with cobalt and tertiary amine catalysts are reported. Addition of cobalt salts leads to a facile low temperature initiation of the polymerization process. The polymerization process was investigated using differential scanning calorimetry [DSC] and vibrating probe rheological measurements. Color changes which occur when the cobalt complex and peroxide are combined were studied using UV-visible spectroscopy. The kinetics of polymerization was investigated using two different cobalt complexes. The initiation step in the polymerization is the conversion of the cobalt (II) to cobalt (III). The presence of the tertiary amine does not affect the oxidation state of the cobalt complex. The cobalt (III) complex gives a better rate of conversion than the cobalt (II) complex. The polymerization process is discussed in terms of redox reaction between the cobalt complex and the alkyperoxide. At low temperatures, the rate of conversion obeys simple Arrhenius kinetics. At higher temperatures the effects of gelation and catalysts inhibition influence the polymerization process. The polymerization process is sensitive to the level of available oxygen during the initiation step and inhibition by aldehyde is observed

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A functionalized polyoxometalate solid for selective oxidation of styrene to benzaldehyde

Cited by 35 publications

References 28 publications

Mono-substituted silicotungstates as active catalysts for sustainable oxidations: homo- and heterogeneous performance

Mono-substituted silicotungstates as active catalysts for sustainable oxidations: homo- and heterogeneous performance

Microstructure and biocompatibility of composite biomaterials fabricated from titanium and tricalcium phosphate by spark plasma sintering

Redox initiated free radical polymerization of 4‐methylstyrene

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