Heterogeneous catalysts for hydroamination reactions: structure–activity relationship

Penzien, Jochen; Haeßner, Carmen; Jentys, Andreas; Köhler, Klaus; Müller, Tobias; Lercher, Johannes A.

doi:10.1016/s0021-9517(03)00283-5

Cited by 90 publications

(80 citation statements)

References 23 publications

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“…Compared with homogeneous catalysts, only a handful of heterogeneous catalysts have been reported. Penzien et al developed metal-exchanged zeolites for alkyne hydroamination, which favors Markovnikov addition products [4][5][6][7]. Pd complex immobilized on silica has been reported for intramolecular cyclization of amino-alkynes [8].…”

Section: Introductionmentioning

confidence: 99%

Hydroamination of Terminal Alkynes by Amines Catalyzed by Copper Heteropoly Salts: A Simple Approach Towards Imine Synthesis

Shanbhag¹,

Palraj²,

Halligudi³

2008

TOOCJ

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Abstract:The hydroamination reaction offers a very attractive route for the synthesis of alkylated amines and their derivatives with no byproduct formation. Heterogeneous intermolecular hydroamination reactions of alkynes with aromatic amines using different inexpensive copper salts of hetropolyacid catalysts were investigated. Among heteropoly salts, copper salts of silicotungstic acid showed highest activity. Reactivity of aromatic amines increased with increase in its basicity. Acidity in heterogeneous catalyst can act as promoter in hydroamination of alkynes.

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Section: Introductionmentioning

confidence: 99%

Hydroamination of Terminal Alkynes by Amines Catalyzed by Copper Heteropoly Salts: A Simple Approach Towards Imine Synthesis

Shanbhag¹,

Palraj²,

Halligudi³

2008

TOOCJ

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“…Zinc-based zeolites have been very effective in the cyclization of 6-aminohex-1-yne, but they have not proven useful with more bulky non-activated alkenes or alkynes, nor have they been shown recyclable. [5] Herein, we report the synthesis and characterization of a zinc-aminotroponiminate (ATI) complex immobilized on mesoporous silica for use as a recyclable catalyst in the intramolecular hydroamination of a non-activated alkene, which to our knowledge, is the first of this kind on functionalized mesoporous silica. Recent studies performed by Roesky and Blechert have shown homogenous zinc aminotroponiminates (ATIs) and zinc amintroponates (ATOs) to be very effective intramolecular hydroamination catalysts for non-activated alkenes and alkynes with a broad range of functional group compatibility.…”

mentioning

confidence: 99%

Aminotroponiminate–Zinc Complex‐Functionalized Mesoporous Materials: Efficient and Recyclable Intramolecular Hydroamination Catalysts

Duncan¹,

Flitsch²,

Asefa³

2009

ChemCatChem

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The formation of nitrogen heterocycles is of considerable interest in the production of fine chemicals, pharmaceuticals, and synthetic natural products. To avoid lengthy synthetic methods, there has been a wealth of research toward these products through intramolecular hydroamination using organoRh, [1] -Pt, [2] , and -Zr [3] complexes, as well as organolanthanides and group three metal complexes [4] as catalysts; such catalysts generally help in generating moderate to excellent yields with good reaction times (7-48 h) for a broad range of reagent functionalities. These materials, however, are generally air sensitive, costly to produce, and lack recyclability necessary for industrial scale syntheses. Zinc-based zeolites have been very effective in the cyclization of 6-aminohex-1-yne, but they have not proven useful with more bulky non-activated alkenes or alkynes, nor have they been shown recyclable.[5]Herein, we report the synthesis and characterization of a zinc-aminotroponiminate (ATI) complex immobilized on mesoporous silica for use as a recyclable catalyst in the intramolecular hydroamination of a non-activated alkene, which to our knowledge, is the first of this kind on functionalized mesoporous silica. Recent studies performed by Roesky and Blechert have shown homogenous zinc aminotroponiminates (ATIs) and zinc amintroponates (ATOs) to be very effective intramolecular hydroamination catalysts for non-activated alkenes and alkynes with a broad range of functional group compatibility. [6,7] Furthermore, these compounds may easily be modified to alter the steric/electronic nature of the catalyst, are relatively stable in air and moisture at various pH levels, and utilize a nontoxic metal. Owing to its bidentate anionic nature, the ATI ligand forms very stable chelate complexes with a variety of metals. [8] Such chelating properties make it an excellent material for heterogeneous catalysis to aid in the prevention of metal (active site) leaching over multiple uses.Synthesis of the ATI ligand was accomplished in a multistep process on highly ordered mesoporous silica SBA-15 with a surface area of 727 m 2 g À1 and pore diameter of 85 by grafting and post-synthesis modification (Scheme 1). Briefly, 3-aminopropyltrimethoxysilane in isopropanol was grafted to serve as the amine source toward imine formation of the ATI complex. Excess silanols were then capped using hexamethyldisilazane to produce capped aminopropyl-functionalized SBA-15 (CAPI) and to reduce possible catalyst/cocatalyst quenching. After capping, the formation of immobilized N-propyl-2-(propylamino)troponimine (DPRT) and [N-propyl-2-(propylamino)troponiminato]methylzinc (ZnDPRT) were carried out as described previously for a solution phase synthesis [6b] with a slightly modified procedure, which produced yellow mesoporous powders.The formation of DPRT was established by FTIR, UV/Vis spectroscopy, thermogravimetric analysis (TGA), 13 C and 29 Si crosspolarization magic angle spinning (CP-MAS) solid state NMR spectroscopy, and elemental anal...

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“…balanced by aluminum atoms which are further apart [40]. On the contrary, a new hump at 621 cm -1 assigned to Zn-S stretching vibration [41] could be seen in the spectrum of ZnS/NaY.…”

Section: +mentioning

confidence: 99%

Novel Synthesis of Nay Zeolite from Rice Husk Silica: Modification with Zno and Zns for Antibacterial Application

Salama¹,

Othman²

2016

Chem Sci J

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Zeolite Y in the sodium form (NaY) was synthesized using amorphous silica ash derived from waste rice husks under hydrothermal conditions. Structural characterization of NaY before and after modification with ZnO and ZnS has been done using powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 adsorption-desorption at -196 °C, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The effects of the Na 2 O/SiO 2 and Si/Al ratios, aging temperature and crystallization time on the optimized synthesis of NaY were thoroughly investigated. Thus the regulated Na + impurity concentration in the starting hydrogel was found to act as a template-assisted synthesis of zeolite NaY by the potential incorporation of Al atoms into the zeolite framework. Results of surface analyses indicate that the interactions of ZnO and ZnS with NaY zeolite are distinguishable and thus the higher interaction is observed for the latter. While Zn II has experienced electrostatic bonding interaction with the framework oxygen atoms, creation of mesopores in NaY due to local destruction of the zeolite lattice around the growing ZnS particles was evidenced. Wonderfully, ZnS/NaY exhibited a high performance in prohibiting the growth of Escherichia coli (E. coli) and negligible from P. Aeruginosa, and these important features make it a potential candidate as an antimicrobial agent for controlling implant-related infections.the utilization of silica from RH for the synthesis of various types of zeolite [8][9][10][11][12][13][14], and mesoporous silica such as . Efforts have also been made to use RH as a source of silica for the synthesis of NaY zeolite with the autoclave process. This low-cost process may lead to production of zeolite NaY to be economically able to compete with established commercial zeolite [16]. Zeolites could selectively adsorb biopolymers like protein, DNA, and RNA, and therefore could be used as chromatographic carriers for these molecules [17][18][19][20]. For these reasons, zeolites would be able to selectively adsorb microbial cells and could be used as cell separation carriers in their native state without surface modifications. Zeolites could adsorb each of the bacterial cell species with high selectivity even from a mixed suspension and could therefore be used as effective carrier materials to provide an easy, rapid and accurate method for cell separation [21]. Zinc oxide supported on zeolite with novel physicochemical properties has recently synthesized [22]. There are some reports regarding the industrial uses of ZnO/ zeolite [23][24][25]. This system can also provide significant impact on the design of a controlled-release product for the pharmacological application in alleviating post-weaning diarrhea of piglets.The aim of this research was to use the RH as an amorphous silica source in the synthesis of NaY zeolite under the optimized experimental conditions. The effects of gel aging and crystallization conditions for the synthesis of NaY under fully optimiz...

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Heterogeneous catalysts for hydroamination reactions: structure–activity relationship

Cited by 90 publications

References 23 publications

Hydroamination of Terminal Alkynes by Amines Catalyzed by Copper Heteropoly Salts: A Simple Approach Towards Imine Synthesis

Hydroamination of Terminal Alkynes by Amines Catalyzed by Copper Heteropoly Salts: A Simple Approach Towards Imine Synthesis

Aminotroponiminate–Zinc Complex‐Functionalized Mesoporous Materials: Efficient and Recyclable Intramolecular Hydroamination Catalysts

Novel Synthesis of Nay Zeolite from Rice Husk Silica: Modification with Zno and Zns for Antibacterial Application

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