An atom-efficient synthetic method: carbosilylations of alkenes, alkynes, and cyclic acetals using Lewis and Brønsted acid catalysts

Motokura, Ken; Baba, Toshihide

doi:10.1039/c2gc16291a

Cited by 34 publications

(9 citation statements)

References 55 publications

(82 reference statements)

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“…Montmorillonite, a layered acidic clay, has recently received much attention as a solid acid catalyst for liquid‐phase organic syntheses . The unique acidity of montmorillonite affords much higher efficiencies for acid‐catalyzed carbon‐carbon/heteroatom bond‐forming reactions such as hydroalkylation and allylsilylation compared with other zeolites and inorganic/organic homogeneous acids at 100–180 °C . In this study, the direct alkylation of benzene using alkanes at 150 °C was carried out using cation‐exchanged montmorillonites as solid acid catalysts.…”

Section: Methodsmentioning

confidence: 99%

“…[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] The unique acidity of montmorillonite affords much higher efficiencies for acid-catalyzed carbon-carbon/ heteroatom bond-forming reactions such as hydroalkylation and allylsilylation compared with other zeolites and inorganic/ organic homogeneous acids at 100-180°C. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] In this study, the direct alkylation of benzene using alkanes at 150°C was carried out using cation-exchanged montmorillonites as solid acid catalysts. The layered structure of the proton-exchanged montmorillonite (H-mont) enabled control of the product selectivity by choosing alkylation of benzene or cracking of alkanes.…”

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confidence: 99%

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Direct Alkylation of Benzene at Lower Temperatures in the Liquid Phase: Catalysis by Montmorillonites as Noble‐Metal‐Free Solid Acids

et al. 2020

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Alkylated benzenes are widely used as raw materials for the production of a variety of chemical compounds. Conventionally, they are obtained by the Friedel‐Crafts reaction between alkyl halides and benzene. In this study, the synthesis of halogen‐free alkylated benzenes was made possible by the direct alkylation of benzene with alkanes using montmorillonites as noble‐metal‐free solid acid catalysts. The direct alkylation of benzene with n‐heptane was performed at 150 °C. Aluminum‐exchanged montmorillonite showed the highest yield of the target C‐7 alkylated products (Ph‐C7) compared with other homogeneous and heterogeneous acid catalysts: 1.8 % conversion of benzene with 58 % selectivity in 16 h. The montmorillonite catalyst system was applied to other linear and cyclic alkanes to give the corresponding alkylated products with good selectivities.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Direct Alkylation of Benzene at Lower Temperatures in the Liquid Phase: Catalysis by Montmorillonites as Noble‐Metal‐Free Solid Acids

et al. 2020

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“…Several comprehensive reviews and accounts of mont-based catalysts have been published [5][6][7][8][9][10][11][12][13][14][15][16]. In contrast, in this short review, we focus on more recent and/or representative examples, including recent studies by our group.…”

Section: Introductionmentioning

confidence: 99%

Montmorillonite-based heterogeneous catalysts for efficient organic reactions

Takabatake

Motokura

2022

Nano Ex.

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In this review, we give a brief overview of recently developed montmorillonite-based heterogeneous catalysts used for efficient organic reactions. Cation-exchanged montmorillonite catalysts, metal catalysts supported on montmorillonite, and an interlayer design used for selective catalysis are introduced and discussed. In traditional syntheses, homogeneous acids and metal salts were used as catalysts, but the difficulty in separation of catalysts from products was a bottleneck when considering industrialization. The use of solid heterogeneous catalysts is one of the major solutions to overcome this problem. Montmorillonite can be used as a heterogeneous catalyst and/or catalyst support. This clay material exhibits strong acidity and a stabilizing effect on active species, such as metal nanoparticles, due to its unique layered structure. These advantages have led to the development of montmorillonite-based heterogeneous catalysts. Acidic montmorillonite, such as proton-exchanged montmorillonite, exhibits a high catalytic activity for the activation of electrophiles, such as alcohols, alkenes, and even alkanes. The montmorillonite interlayer/surface also functions as a good support for various metal species used for oxidation and carbon-carbon bond forming reactions. The use of an interlayer structure enables selective reactions and the stabilization of catalytically active species.

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“…4 However, retention of their selectivity and reusability after several reaction cycles is very challenging. 5 During the past few years, various catalysts have been exploited for diverse chemical reactions such as Lewis acids, 6 amine-functionalized solid supports, 7 ionic liquids, 8 zeolites, 9,10 and metal organic frameworks. 5,11 However, these catalysts offer several disadvantages such as utilization of hazardous and carcinogenic solvents, large amount of catalysts, long reaction time, nonrecoverable catalysts, and generation of secondary products that hindered their large-scale industrial application.…”

Section: ■ Introductionmentioning

confidence: 99%

“…However, retention of their selectivity and reusability after several reaction cycles is very challenging . During the past few years, various catalysts have been exploited for diverse chemical reactions such as Lewis acids, amine-functionalized solid supports, ionic liquids, zeolites, , and metal organic frameworks. , However, these catalysts offer several disadvantages such as utilization of hazardous and carcinogenic solvents, large amount of catalysts, long reaction time, nonrecoverable catalysts, and generation of secondary products that hindered their large-scale industrial application. , Therefore, it is highly desirable to develop efficient recoverable solid-phase catalyst that can overcome these problems and show high activity as well as maximum reusability. Hence, in the present study, we have explored an alternate perovskite as a catalyst for three different types of catalytic reactions.…”

Section: Introductionmentioning

confidence: 99%

Structural Studies of Multifunctional SrTiO₃ Nanocatalyst Synthesized by Microwave and Oxalate Methods: Its Catalytic Application for Condensation, Hydrogenation, and Amination Reactions

2018

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The present study deals with the synthesis of SrTiO 3 (STO) nanocatalysts by conventional oxalate and microwave-assisted hydrothermal methods. Thorough characterization of the nanocatalysts synthesized has been done by using various techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy, N 2 physisorption, transmission electron microscopy, total acidity by pyridine adsorption method, and acidic strength by n -butylamine potentiometric titration, respectively. Structural parameters were estimated by Rietveld refinement analysis from XRD data which confirms cubic structure of SrTiO 3 . Traces of impurities such as TiO 2 and SrCO 3 were found in conventional catalysts, whereas these are absent in microwave catalyst. Brunauer–Emmett–Teller (BET) surface area of the microwave catalyst was enhanced 14-folds compared to conventional catalyst. Increase in Lewis acid sites and their strength were also observed in STO microwave catalyst. Catalytic performance of the catalysts was evaluated for various reactions, such as Knoevenagel condensation of benzaldehyde, catalytic transfer hydrogenation of nitrobenzene, and amination of benzaldehyde. Catalytic results reveal that microwave-synthesized catalyst showed 100% conversion and selectivity (>99% yield) for the chosen reactions than the conventional catalyst. Excellent catalytic activity of the STO microwave catalyst was due to high BET surface area, pore volume, and acidity of the catalyst, as compared to conventional catalyst. The present study marks the first-time application of perovskite-based SrTiO 3 as a potential multitasking cost-effective catalyst for the above reactions and synthesized using environment friendly microwave synthesis method.

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An atom-efficient synthetic method: carbosilylations of alkenes, alkynes, and cyclic acetals using Lewis and Brønsted acid catalysts

Cited by 34 publications

References 55 publications

Direct Alkylation of Benzene at Lower Temperatures in the Liquid Phase: Catalysis by Montmorillonites as Noble‐Metal‐Free Solid Acids

Direct Alkylation of Benzene at Lower Temperatures in the Liquid Phase: Catalysis by Montmorillonites as Noble‐Metal‐Free Solid Acids

Montmorillonite-based heterogeneous catalysts for efficient organic reactions

Structural Studies of Multifunctional SrTiO₃ Nanocatalyst Synthesized by Microwave and Oxalate Methods: Its Catalytic Application for Condensation, Hydrogenation, and Amination Reactions

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An atom-efficient synthetic method: carbosilylations of alkenes, alkynes, and cyclic acetals using Lewis and Brønsted acid catalysts

Cited by 34 publications

References 55 publications

Direct Alkylation of Benzene at Lower Temperatures in the Liquid Phase: Catalysis by Montmorillonites as Noble‐Metal‐Free Solid Acids

Direct Alkylation of Benzene at Lower Temperatures in the Liquid Phase: Catalysis by Montmorillonites as Noble‐Metal‐Free Solid Acids

Montmorillonite-based heterogeneous catalysts for efficient organic reactions

Structural Studies of Multifunctional SrTiO3 Nanocatalyst Synthesized by Microwave and Oxalate Methods: Its Catalytic Application for Condensation, Hydrogenation, and Amination Reactions

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Product

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Structural Studies of Multifunctional SrTiO₃ Nanocatalyst Synthesized by Microwave and Oxalate Methods: Its Catalytic Application for Condensation, Hydrogenation, and Amination Reactions