Selective Photo-epoxidation of (R)-(+)- and (S)-(−)-Limonene by Chiral and Non-Chiral Dioxo-Mo(VI) Complexes Anchored on TiO2-Nanotubes

Q, Henry Martinez; Páez‐Mozo, Edgar A.

doi:10.1007/s11244-020-01355-3

Cited by 17 publications

(9 citation statements)

References 47 publications

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“…The selectivity values observed, on the contrary, do show that the MoO 2 unit is more selective being directly functionalized onto the solid metal-organic structure. This phenomenon has been previously observed in epoxidation reactions of natural products such as Limonene and alphapinene, using different supports, and has been associated with the stability generated at the active center, when it is incorporated covalently on a solid structure, originating a more selective process towards the epoxide [102][103][104]. Additionally, when MoO 2 Cl 2 @COMOC-4 was compared with heterogeneous catalysts based on oxo-tungsten active centers (Entry 4-5, Table 3), SiO 2 , Amberlite IR-120, or AlO 3 solid supports that use inorganic acids as co-catalysts (Entry 7-9, Table 3), the same trend was observed in the conversion and selectivity values.…”

Section: Influence Of Temperaturementioning

confidence: 54%

Soybean Oil Epoxidation Catalyzed by a Functionalized Metal–Organic Framework with Active Dioxo-Molybdenum (VI) Centers

Trujillo

Carriazo

et al. 2022

Catal Lett

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In this work, a functionalized gallium metal–organic framework with active dioxo-molybdenum (VI) centers was evaluated as a catalyst in the epoxidation of soybean oil using tert-butyl-hydroperoxide as an oxidizing agent. The influence of the reaction time, temperature, and concentration of the oxidizing agent was studied, and it was demonstrated that the highest epoxide selectivity was obtained at 110 °C after 4 h of reaction (29% conversion and 91% selectivity) using a soybean oil/oxidizing agent ratio of 1/2. The stability of the metal–organic framework was confirmed by infrared spectroscopy, X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy EDS. The stability tests demonstrated that the catalyst could be reused in the catalytic process for the recovery of vegetable oils. Graphical Abstract

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Section: Influence Of Temperaturementioning

confidence: 54%

Soybean Oil Epoxidation Catalyzed by a Functionalized Metal–Organic Framework with Active Dioxo-Molybdenum (VI) Centers

Trujillo

Carriazo

et al. 2022

Catal Lett

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“…The grafting of the organic molecule on the solid matrix is accompanied by a trimethylsilanol formation, which can easily be eliminated as volatile hexamethyldisiloxane and water [33–35] . This silyl ether substitution on the surface has been previously described as an effective synthetic route to obtain carboxylate‐covalent grafted materials without desorption of the linker moiety [35–37] and a synergistic chemical bond for hybrid catalysts participating in photoinduced electron transfer processes [38,39] …”

Section: Resultsmentioning

confidence: 99%

Stability and Performance Enhancement of an Oligo (phenylene vinylene) Photocatalyst via Surface Grafting onto TiO₂ for Visible‐Light Indigo Carmine Degradation

2022

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The chemical immobilization of a dibenzoic acid oligo (phenylene vinylene) (OPV) derivative for TiO2 sensitization was evaluated as a strategy to enhance both the stability and photocatalytic performance of this π‐conjugated moiety when applied to the photodegradation of indigo carmine dye (IC) as model pollutant. The results show that the electron injection from the photoexcited OPV to the TiO2 conduction band remarkably boosts the IC degradation ability under visible light illumination. The use of SiO2 as non‐photoactive support was also investigated to simultaneously determine the role of the inorganic support in the photocatalytic process. The spectroscopic, thermal, and surface characterization validated the successful grafting of the OPV to the inorganic supports. Moreover, superoxide radical and singlet oxygen were established as the active species involved in the dye degradation identifying an additional direct reducing pathway. Interestingly, the use of electron donors proved to be an ineffective approach to increase the system performance, entailing that the OPV regeneration proceeds chiefly via back electron transfer processes. Finally, the reusability tests confirmed that TiO2/OPV material retains up to 86 % of their photocatalytic activity during the first five cycles, demonstrating a critical enhancement in the organic conjugated framework stability.

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“…Recently, the photocatalytic activity of a dioxo-molybdenum complex supported on nanostructured TiO 2 was assessed in the selective epoxidation of terpenic structures such as limonene and α-and β-pinene, using molecular O 2 as the primary oxidizing agent. These results showed that immobilization of the dioxomolybdenum complex not only resulted in an increased stability of the MoO 2 active units but also resulted in an enhanced transfer rate of oxygen atoms besides its specific capacity to be reoxidized by the interaction with O 2 [30][31][32].…”

Section: Introductionmentioning

confidence: 88%

Photo-epoxidation of (α, β)-pinene with molecular O2 catalyzed by a dioxo-molybdenum (VI)-based Metal–Organic Framework

Castellanos

Ortega

et al. 2021

Res Chem Intermed

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A gallium-based metal-organic framework, post-modified with MoO 2 Cl 2 , was examined as a catalyst for the room temperature liquid-phase photooxidation of α-and β-pinene in the presence of molecular oxygen as the oxidant. For both substrates, (α, β)-pinene oxide was formed as the sole product due to the oxygen atom transfer process. Peroxo-molybdenum species was identified in the reoxidation process using infrared spectroscopy. Moreover, a comparison of the structure of the catalyst before and after catalysis by means of X-ray powder diffraction (XRPD), infrared spectroscopy (IR) and N 2 adsorption-desorption measurements demonstrated the high recyclability and potential of this catalyst in the photocatalytic epoxidation process of terpenes.

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Selective Photo-epoxidation of (R)-(+)- and (S)-(−)-Limonene by Chiral and Non-Chiral Dioxo-Mo(VI) Complexes Anchored on TiO2-Nanotubes

Cited by 17 publications

References 47 publications

Soybean Oil Epoxidation Catalyzed by a Functionalized Metal–Organic Framework with Active Dioxo-Molybdenum (VI) Centers

Soybean Oil Epoxidation Catalyzed by a Functionalized Metal–Organic Framework with Active Dioxo-Molybdenum (VI) Centers

Stability and Performance Enhancement of an Oligo (phenylene vinylene) Photocatalyst via Surface Grafting onto TiO₂ for Visible‐Light Indigo Carmine Degradation

Photo-epoxidation of (α, β)-pinene with molecular O2 catalyzed by a dioxo-molybdenum (VI)-based Metal–Organic Framework

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Selective Photo-epoxidation of (R)-(+)- and (S)-(−)-Limonene by Chiral and Non-Chiral Dioxo-Mo(VI) Complexes Anchored on TiO2-Nanotubes

Cited by 17 publications

References 47 publications

Soybean Oil Epoxidation Catalyzed by a Functionalized Metal–Organic Framework with Active Dioxo-Molybdenum (VI) Centers

Soybean Oil Epoxidation Catalyzed by a Functionalized Metal–Organic Framework with Active Dioxo-Molybdenum (VI) Centers

Stability and Performance Enhancement of an Oligo (phenylene vinylene) Photocatalyst via Surface Grafting onto TiO2 for Visible‐Light Indigo Carmine Degradation

Photo-epoxidation of (α, β)-pinene with molecular O2 catalyzed by a dioxo-molybdenum (VI)-based Metal–Organic Framework

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Stability and Performance Enhancement of an Oligo (phenylene vinylene) Photocatalyst via Surface Grafting onto TiO₂ for Visible‐Light Indigo Carmine Degradation