Tandem, Effective Continuous Flow Process for the Epoxidation of Cyclohexene

He, Wei; Fang, Zheng; Tian, Qitao; Shen, Weidong; Guo, Kai

doi:10.1021/acs.iecr.5b04187

Cited by 12 publications

(10 citation statements)

References 74 publications

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“…As a matrix of Ag particles, TiO 2 -SiO 2 particles possess higher activity for the epoxidation of cyclohexene and can provide more active sites for the adsorption of cyclohexene and therefore improve the cyclohexene conversion over Ag-TS catalyst. Our repeatable work is better than other similar researches [ 33 – 35 ], this demonstrates that TiO 2 -SiO 2 in Ag-TS has led to a synergetic action. The presence of the TiO 2 -SiO 2 composite oxide can enhance the reactants from contacting with the active sites using Ag-TS catalyst.…”

Section: Resultssupporting

confidence: 50%

Heterogeneous Ag-TiO2-SiO2 composite materials as novel catalytic systems for selective epoxidation of cyclohexene by H2O2

et al. 2017

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TiO2-SiO2 composites were synthesized using cetyl trimethyl ammonium bromide (CTAB) as the structure directing template. Self-assembly hexadecyltrimethyl- ammonium bromide TiO2-SiO2/(CTAB) were soaked into silver nitrate (AgNO3) aqueous solution. The Ag-TiO2-SiO2(Ag-TS) composite were prepared via a precipitation of AgBr in soaking process and its decomposition at calcination stage. Structural characterization of the materials was carried out by various techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption and ultraviolet visible spectroscopy (UV-Vis). Characterization results revealed that Ag particles were incorporated into hierarchical TiO2-SiO2 without significantly affecting the structures of the supports. Further heating-treatment at 723 K was more favorable for enhancing the stability of the Ag-TS composite. The cyclohexene oxide was the major product in the epoxidation using H2O2 as the oxidant over the Ag-TS catalysts. Besides, the optimum catalytic activity and stability of Ag-TS catalysts were obtained under operational conditions of calcined at 723 K for 2 h, reaction time of 120 min, reaction temperature of 353 K, catalyst amount of 80 mg, aqueous H2O2 (30 wt.%) as oxidant and chloroform as solvent. High catalytic activity with conversion rate up to 99.2% of cyclohexene oxide could be obtainable in water-bathing. The catalyst was found to be stable and could be reused three times without significant loss of catalytic activity under the optimized reaction conditions.

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Section: Resultssupporting

confidence: 50%

Heterogeneous Ag-TiO2-SiO2 composite materials as novel catalytic systems for selective epoxidation of cyclohexene by H2O2

et al. 2017

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“…1–4 Such strategies remain sought after due to the need for cyclohexenes as building blocks and their common occurrence in nature. 5 Inspired by natural products, including pinnatal, jerantiphylline A, and myricolal (Figure 1b), 6 we designed a metal-catalyzed isomerization to generate cyclohex-3-enecarbaldehydes bearing α-quaternary centers. 7 Herein, we disclose a desymmetrization of bisallylaldehydes 1 to generate cyclohexenes 4 via the desymmetrization of prochiral quaternary centers (Figure 1c-route A).…”

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confidence: 99%

Rhodium-Catalyzed Enantioselective Cycloisomerization to Cyclohexenes Bearing Quaternary Carbon Centers

2016

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We report a Rh-catalyzed enantioselective cycloisomerization of α,ω-heptadienes to afford cyclohexenes bearing quaternary carbon centers. Rhodium(I) and a new SDP ligand promote chemoselective formation of a cyclohex-3-enecarbaldehyde motif that is inaccessible by the Diels–Alder cycloaddition. Various α,α-bisallylaldehydes rearrange to generate six-membered rings by a mechanism triggered by aldehyde C–H bond activation. Mechanistic studies suggest a pathway involving regioselective carbometallation and endocyclic β-hydride elimination.

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“…Using flow methods m ‐CPBA was generated in situ and converted cyclohexene into high quality cyclohexene oxide. The peracid was obtained within few seconds at room temperature by reacting m ‐chlorobenzoyl chloride with hydrogen peroxide . Moreover, Gao, Chen and co‐workers used either m ‐CPBA or AcOOH as oxidizing agents for asymmetric epoxidations of electron‐deficient olefins in high yields (up to 90 %) and excellent enantioselectivities (up to 92 % ee )…”

Section: [2+1] Cycloaddition: 3‐membered Ringsmentioning

confidence: 99%

Flow Chemistry for Cycloaddition Reactions

2020

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Continuous flow reactors form part of a rapidly growing research area that has changed the way synthetic chemistry is performed not only in academia but also at the industrial level. This Review highlights the most recent advances in cycloaddition reactions performed in flow systems. Cycloadditions are atom-efficient transformations for the synthesis of carbo-and heterocycles, involved in the construction of challenging skeletons of complex molecules. The main advantages of translating these processes into flow include using intensified conditions, safer handling of hazardous reagents and gases, easy tuning of reaction conditions, and straightforward scaling up. These benefits are especially important in cycloadditions such as the copper(I)-catalyzed azide alkyne cycloaddition (CuAAC), Diels-Alder reaction, ozonolysis and [2 + 2] photocycloadditions. Some of these transformations are key reactions in the industrial synthesis of pharmaceuticals.

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Tandem, Effective Continuous Flow Process for the Epoxidation of Cyclohexene

Cited by 12 publications

References 74 publications

Heterogeneous Ag-TiO2-SiO2 composite materials as novel catalytic systems for selective epoxidation of cyclohexene by H2O2

Heterogeneous Ag-TiO2-SiO2 composite materials as novel catalytic systems for selective epoxidation of cyclohexene by H2O2

Rhodium-Catalyzed Enantioselective Cycloisomerization to Cyclohexenes Bearing Quaternary Carbon Centers

Flow Chemistry for Cycloaddition Reactions

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