由预先形成的以多孔阴离子交换树脂为模板的钛硅酸盐溶液合成直径为0.5-1.5 mm的多孔钛硅酸盐珠(TiSil-HPB-60)。这种材料的珠粒形式使其能够在直接用作液相多相催化剂时从反应混合物中分离出来。该材料显示出分层孔隙率(微孔/中孔)和初始TS-1结构构建单元。钛物质主要位于四面体骨架位置。TiSil-HPB-60是一种高活性催化剂,可用于环己烯与叔丁基氢过氧化物(TBHP)和H 2 O 2水溶液的环氧化。两种氧化剂都比Ti-MCM-41和TS-1的TiSil-HPB-60的环氧收率更高。TiSil-HPB-60的催化性能提高主要归因于较大的中孔,有利于试剂和产物与钛活性位之间的扩散。通过钛硅酸盐珠的甲硅烷基化可以进一步提高环氧化物的产率和选择性。重要的是,TiSil-HPB-60是一种稳定的催化剂,可防止钛浸出,并且可以轻松回收并在连续的催化循环中重复使用,而不会造成重大活性损失。
Epoxidation of Cyclooctene Using Water as the Oxygen Atom Source at Manganese Oxide Electrocatalysts
作者:Kyoungsuk Jin、Joseph H. Maalouf、Nikifar Lazouski、Nathan Corbin、Dengtao Yang、Karthish Manthiram
DOI:10.1021/jacs.9b02345
日期:2019.4.17
oxide nanoparticles (NPs) are shown to catalyze cyclooctene epoxidation with Faradaic efficiencies above 30%. Isotopic studies and detailed product analysis reveal an overall reaction in which water and cyclooctene are converted to cyclooctene oxide and hydrogen. Electrokinetic studies provide insights into the mechanism of olefinepoxidation, including an approximate first-order dependence on the substrate
type of heterogeneous molybdenum (+6) complex, prepared by covalent grafting of cis-dioxo‑molybdenum (VI) pyridylimine complex on the surface of MnFe2O4 nanoparticles (NP) and characterized using various physicochemical techniques. The recyclable prepared nanocatalyst was tested for sulfoxidation of sulfides and epoxidation of alkenes under solvent-free condition. The catalyst exhibited high turnover
在本文中,我们报道了一种新型的异质钼(+6)络合物,它是通过共价接枝MnFe 2 O 4纳米颗粒(NP)表面上的顺式-二氧杂钼(VI)嘧啶复合物制备的,并使用各种理化技术。测试了可循环制备的纳米催化剂在无溶剂条件下硫化物的硫氧化和烯烃的环氧化。该催化剂对环辛烯和环己烯(10,850 h -1),硫代苯甲醚和二甲基硫醚(41,250 h -1)的氧化具有较高的周转频率。)。发现合成的催化剂是高效的,可回收的和环境友好的催化剂,用于在短时间内以优异的产率进行烯烃和硫化物的(环)氧化。此外,合成的纳米催化剂可以重复使用四次,而在氧化反应中其催化活性没有明显损失。
Organocatalytic epoxidation and allylic oxidation of alkenes by molecular oxygen
作者:Marina Petsi、Maria Orfanidou、Alexandros L. Zografos
DOI:10.1039/d1gc03029a
日期:——
reduction of dioxygen by Hantzsch ester under mild conditions to allow the aerobic metal-free epoxidation of electron-rich alkenes. Mechanistic crossovers are underlined, explaining the dual role of Hantzsch ester as a reductant/promoter of the DKP catalyst and a simultaneous competitor for the epoxidation of alkenes when HFIP is used as a solvent. Expansion of this protocol to the synthesis of allylic alcohols
Synthesis and characterization of a novel nanomagnetic phase-transfer catalyst and its application to regioselective synthesis of β-azido and β-nitro alcohols in water
作者:N. Ayashi、M. Fallah-Mehrjardi、A. R. Kiasat
DOI:10.1134/s1070428017060069
日期:2017.6
Fe3O4 nanoparticles through hexane-1,6-diyldicarbamate linker afforded a powerful and reusable heterogeneous phase-transfer catalysis which was successfully used for regioselectiveringopening of epoxides with azide and nitrite anions in aqueous medium. The new catalyst can readily be recovered by simple magnetic decantation and recycled several times without appreciable loss of catalytic activity
通过己烷-1,6-二基二氨基甲酸酯连接基将聚乙二醇取代的1-甲基咪唑溴化铵固定在磁性Fe 3 O 4纳米颗粒的表面上,提供了有力且可重复使用的异相转移催化,该催化转移反应已成功用于环氧化物的区域选择性开环水性介质中的叠氮化物和亚硝酸根阴离子。通过简单的磁倾析法可以很容易地回收新催化剂,并循环使用几次,而不会明显丧失催化活性。
Greener and facile aqueous regioselective synthesis of vicinal azidoalcohols using silica-bound 3-((polyethyleneglycol)ethyl)-8-methyl-1H-imidazol-3-ium bromide as a recyclable catalyst
benign, aqueous synthesis of vicinal azidoalcohols by the regioselective nucleophilic ring opening of epoxides with azide anion using silica-bound 3-((polyethyleneglycol)ethyl)-8-methyl-1H-imidazol-3-ium bromide as an effective heterogeneous phase transfer catalyst is described. Short reaction time, simple work-up procedure, high yield, reusability, and use of an eco-friendly catalyst are some of the