High-silica Hβ zeolites for catalytic hydration of hydrophobic epoxides and alkynes in water

Poly, Sharmin Sultana; Siddiki, S. M. A. Hakim; Touchy, Abeda S.; Yasumura, Shunsaku; Toyao, Takashi; Maeno, Zen; Shimizu, Ken‐ichi

doi:10.1016/j.jcat.2018.10.004

Cited by 27 publications

(12 citation statements)

References 54 publications

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“…This step is anticipated to be much faster than the rate-limiting step of protonation of esters in hydrolysis over hydrophilic siloxane gel catalysts. Thus, the hydrophobic environment surrounding the Brønsted acid site is believed to significantly enhance the reaction rate of ester hydrolysis. , The increase of hydrophobicity at the acid site should decrease the accessibility of water to protonated esters. Thus, the nucleophilic attack of water to the activated hydrophobic esters should mainly take place at the water/organic phase interface where water can contact organic molecules with high frequency.…”

Section: Resultsmentioning

confidence: 99%

Quantitative Evaluation of the Effect of the Hydrophobicity of the Environment Surrounding Brønsted Acid Sites on Their Catalytic Activity for the Hydrolysis of Organic Molecules

et al. 2018

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Sulfo-functionalized siloxane gels with a variety of surface hydrophobicities were fabricated to elucidate the effect of the environment surrounding the Brønsted acid site on their catalytic activity for the hydrolysis of organic molecules. A detailed structural analysis of these siloxane gels by elemental analysis, X-ray photoelectron spectroscopy, Fourier-transformed infrared (FT-IR), and 29Si MAS NMR revealed the formation of gel catalysts with a highly condensed siloxane network, which enabled us to quantitatively evaluate the hydrophobicity of the environment surrounding the catalytically active sulfo-functionality. A sulfo group in a highly hydrophobic environment exhibited excellent catalytic turnover frequency for the hydrolysis of acetate esters with a long alkyl chain, whereas not only conventional solid acid catalysts but also liquid acids showed quite low catalytic activity. Detailed kinetic studies corroborated that the adsorption of oleophilic esters at the Brønsted acid site was facilitated by the surrounding hydrophobic environment, thus significantly promoting hydrolysis under aqueous conditions. Furthermore, sulfo-functionalized siloxane gels with a highly hydrophobic surface showed excellent catalytic activity for the hydrolytic deprotection of silyl ethers.

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Section: Resultsmentioning

confidence: 99%

Quantitative Evaluation of the Effect of the Hydrophobicity of the Environment Surrounding Brønsted Acid Sites on Their Catalytic Activity for the Hydrolysis of Organic Molecules

et al. 2018

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“…However, H‐MOR(220) gave a higher product formation rate calculated based on the number of protonic sites (Figure ). This could be attributed to the fact that increasing SiO 2 /Al 2 O 3 ratio enhances the hydrophobic interaction between the zeolite pores and the substrate, which in this case, benzene, thus leading to a higher product formation rate when adjusted to the number of protonic sites …”

Section: Figurementioning

confidence: 99%

Catalytic Methylation of Aromatic Hydrocarbons using CO₂/H₂ over Re/TiO₂ and H‐MOR Catalysts

et al. 2020

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A combined catalyst comprising TiO 2 -supported Re (Re(1)/TiO 2 ; Re = 1 wt%) and H-MOR (SiO 2 /Al 2 O 3 = 90) was found to promote the methylation of benzene using CO 2 and H 2 . This catalytic system exhibited high performance with regard to the synthesis of methylated benzenes and gave high yields of total methylated products (up to 52 % benzene-based yield and 42 % CO 2based yield) under the reaction conditions employed in this study (p CO2 = 1 MPa; p H2 = 5 MPa; T = 250°C; t = 20 h) in a batch reactor. Catalyst screening demonstrated that a combination of Re(1)/TiO 2 and H-MOR (SiO 2 /Al 2 O 3 = 90) exhibited superior performance compared to other combinations of supported metal catalysts and zeolites in terms of both yield and selectivity for methylated benzenes.

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“…For example, the synthesis of trans -1,2-cyclohexanediol can be achieved efficiently over the MoO 3 catalyst from the oxidation of a cyclohexene using tert -butyl hydrogen peroxide (TBHP) as the oxidant, providing a high conversion (93%) as well as a high selectivity toward 1,2-cyclohexanediol (98.2%); two alternative reaction paths were reported to establish green protocols for diols syntheses, i.e., oxidative dihydroxylation of cyclohexene to trans -1,2-cyclohexanediol and hydrogenation of catechol to a mixture of cis- and trans -1,2-cyclohexanediol . In the past few decades, epoxide hydration using solid catalysts has attracted much interest and is considered as a promising, highly effective, and eco-friendly method; various heterogeneous catalysts, including zeolites, − polymer-supported catalysts, Co(III)–salen complexes, − transition metal oxides, and Lewis bases have been investigated to synthesize 1,2-diols via epoxide hydration. The common characteristics of these employed catalysts is to provide acidic or basic centers to activate epoxides and thus hasten the nucleophilic addition by water molecules.…”

Section: Introductionmentioning

confidence: 99%

Ring-Opening Hydration of Epoxides into Diols with a Low Water–Epoxide Ratio Catalyzed by a Fe-Incorporated Octahedra-Based Molecular Sieve

et al. 2021

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1,2-Diols are important organic intermediates in the production of a variety of organic chemicals, and their eco-friendly production has attracted much attention, especially from epoxide hydration using solid-acid catalysts. Herein, Fe 3+incorporated PKU-1 molecular sieve (Fe−PKU-1), an open-framework and octahedra-based aluminoborate with 18-membered-ring channels, was successfully synthesized and behaved as a solid Lewis acid to catalyze the ring-opening hydration of epoxides. The as-synthesized Fe−PKU-1 catalyst has a high catalytic efficiency at a low water−epoxide ratio and better structural stability. The comparative tests indicated that some other Fe-containing catalysts only had a very low catalytic activity, which confirmed the structure-sensitive role of Fe 3+ doped in the PKU-1 framework. Reaction kinetics analyses showed that the hydration reaction is a firstorder reaction and has a lower apparent activation energy (∼30 kJ•mol −1 ). Further investigations discovered that trans-1,2-cyclohexanediol was exclusively formed through a nucleophilic addition when using cyclohexene oxide as substrate molecule, and the adsorption experiment indicated an extremely high amount of epoxide was accumulated in the solid/liquid interface of Fe− PKU-1, which is nearly 100 times higher than that of Fe-free PKU-1. On the basis of the above results, a plausible catalytic mechanism was proposed to elucidate the epoxide hydration process.

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High-silica Hβ zeolites for catalytic hydration of hydrophobic epoxides and alkynes in water

Cited by 27 publications

References 54 publications

Quantitative Evaluation of the Effect of the Hydrophobicity of the Environment Surrounding Brønsted Acid Sites on Their Catalytic Activity for the Hydrolysis of Organic Molecules

Quantitative Evaluation of the Effect of the Hydrophobicity of the Environment Surrounding Brønsted Acid Sites on Their Catalytic Activity for the Hydrolysis of Organic Molecules

Catalytic Methylation of Aromatic Hydrocarbons using CO₂/H₂ over Re/TiO₂ and H‐MOR Catalysts

Ring-Opening Hydration of Epoxides into Diols with a Low Water–Epoxide Ratio Catalyzed by a Fe-Incorporated Octahedra-Based Molecular Sieve

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High-silica Hβ zeolites for catalytic hydration of hydrophobic epoxides and alkynes in water

Cited by 27 publications

References 54 publications

Quantitative Evaluation of the Effect of the Hydrophobicity of the Environment Surrounding Brønsted Acid Sites on Their Catalytic Activity for the Hydrolysis of Organic Molecules

Quantitative Evaluation of the Effect of the Hydrophobicity of the Environment Surrounding Brønsted Acid Sites on Their Catalytic Activity for the Hydrolysis of Organic Molecules

Catalytic Methylation of Aromatic Hydrocarbons using CO2/H2 over Re/TiO2 and H‐MOR Catalysts

Ring-Opening Hydration of Epoxides into Diols with a Low Water–Epoxide Ratio Catalyzed by a Fe-Incorporated Octahedra-Based Molecular Sieve

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Catalytic Methylation of Aromatic Hydrocarbons using CO₂/H₂ over Re/TiO₂ and H‐MOR Catalysts