共查询到20条相似文献,搜索用时 24 毫秒
1.
Dongmin Zhao Jiquan Zhao Shanshan Zhao Weiyu Wang 《Journal of Inorganic and Organometallic Polymers and Materials》2007,17(4):653-659
A chiral Manganese (III) salen complex was immobilized on the walls of MCM-41 (mobile crystalline material) through the multi-grafting
method. The immobilized complex was characterized by XRD, FTIR, UV-Vis, ICP and Nitrogen sorption, and was applied to the
asymmetric epoxidation of unfuctionalized alkenes including 1,2-dihydronaphthalene, α-methylstyrene, cis-β-methylstyrene, styrene using NaClO and m-chloroperbenzoic acid (m-CPBA) as oxidants respectively. The immobilized complex showed good activity and enantioselectivity in the epoxidation of
1,2-dihydronaphthalene by using NaClO as oxidant. It could also be run for 4 times in the epoxidation of α-methylstyrene without
obvious loss of activity or enantiomeric excess. 相似文献
2.
The supported ZSM-5 film was synthesized hydrothermally on the porous supports such as Anodisc and alumina tube. The enantioselective hydrolytic resolution of racemic epoxides was performed in the ZSM-5/Anodisc membrane reactor containing chiral salen complexes. The chiral (Co-salen)+PF6 - and (Co-salen)+BF4 - complexes immobilized on the membrane showed a very high enantioselectivity and recyclability in the hydrolysis of epichlorohydrine, 1,2-epoxybutane, 1,2-epoxyhexane and styrene oxide. It was easy to separate the products, and the catalysts could be recycled without observable loss in activity and enantioselectivity using the batch-type and continuous-type membrane reactor. The obtained epoxide product remained in the organic phase and the hydrophilic water-soluble diols diffused into the aqueous phase through the ZSM-5 film layer. 相似文献
3.
Dae-Woon Park Sung-Dae Choi Soon-Ja Choi Chung-Young Lee Geon-Joong Kim 《Catalysis Letters》2002,78(1-4):145-151
Organosilane-modified mesoporous materials have been prepared under mild and acidic conditions by a solvent evaporation method using C16TMABr surfactant as a template. The mesoporous samples synthesized in ethanol solvent by using this evaporation method showed a fully disordered pore system, but those obtained under hydrothermal conditions had highly ordered pores. The chiral salen Mn(III) complexes were immobilized on these organosilane-functionalized mesoporous silicas by a grafting method. The catalysts used in the asymmetric epoxidation of styrene and cis-stilbene and the effect of different mesoporous structures on the reactivity was investigated. Similar enantioselectivities were observed by using these heterogenized salen complexes as compared with reaction under homogeneous conditions. 相似文献
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A series of typical methyl regulators were used to finely modify the Cr(salen) complex immobilized on MCM-41. Such immobilized
complexes were effective catalysts for solvent-free selective oxidation of benzyl alcohol (BzOH) with 30% hydrogen peroxide
(H2O2), and they all exhibited much higher catalytic performance than their homogeneous analogue. Simultaneously, the introduction
of methyl regulators was found to significantly improve the catalytic performance of immobilized complexes by modifying their
surface properties. The optimal BzOH conversion reached 65.0% with 100% selectivity to benzaldehyde (BzH). 相似文献
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MFI structural zeolite (ZSM-5 and Sililcalite) was treated with hot NaOH solution to make mesoporous channels in the microporous crystals. Inner mesopore size could be controlled by changing the concentration of NaOH solution. The pore structure of alkaline-treated MFI zeolite was studied by instrumental analysis. To obtain the cage type mesopores, Ti-coating on the outside MFI crystals before alkaline treatment was investigated to be the most effective. Co(III) salen complexes monomers were successfully encapsulated in mesoporous MFI-type zeolite by “ship-in-a-bottle” method. The heterogeneous catalyst could be applied in asymmetric ring opening of terminal epoxides by phenol derivatives. It showed very high enantioselectivity with yield in the catalysis. 相似文献
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de Souza Magossi Maiara Fernandes Daniela Silvestrini dos Santos Franco Fernanda dos Santos Felipe Alexsandro de Vicente Fábio Simões do Carmo Devaney Ribeiro 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(10):4093-4102
Journal of Inorganic and Organometallic Polymers and Materials - In this work, it describes the preparation of Titanium and Zirconium functionalized MCM-41 and subsequent chemical modification with... 相似文献
8.
B.M. Choudary N. Sreenivasa Chowdari M. Lakshmi Kantam P. Lakshmi Santhi 《Catalysis Letters》2001,76(3-4):213-218
Heterogeneous Mn(III) chiral salen complexes are prepared through covalent attachment of salen ligand on silica gel via chloropropyl spacer and subsequent complexation with manganese. The complexes are well characterized by IR, UV/VIS, TGA and elemental analysis. Epoxidation of unfunctionalised prochiral olefins by Mn(III) chiral salen complexes using iodosobenzene and m-CPBA as the terminal oxidants and NMO as a co-oxidant was achieved with good yields albeit low enantiomeric excess. 相似文献
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In the present letter, for the first time, the efficacy of hydrotalcite-like layered double hydroxides (LDHs) materials as alternative and novel catalyst precursors for the synthesis of carbon nanotubes (CNTs) via catalytic chemical vapor deposition (CCVD) of acetylene was reported. Nanometer-sized cobalt particles were prepared by calcination of a single molecular LDH precursor containing cobalt (II) and aluminum (III) and following by a process of reduction. Multi-walled CNTs with uniform diameters were obtained using the as-synthesized catalyst in the reaction. 相似文献
11.
Robert Glaser Shimona Geresh Jeanine Blumenfeld Baruch Vainas Menachem Twaik 《Israel journal of chemistry》1976,15(1-2):17-21
Z-(−)-(1R, 3R, 4S)-menthyl-α-acetamidocinnamate was hydrogenated with neutral diphosphine-rhodium(I) complexes containing (+)-(2S, 3S) or (−)-(2R, 3R)-2,3-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane(DIOP) to give a diastereomeric mixture of N-acetylphenylalanine (1R, 3R, 4S)-menthyl ester (76.8% diastereomeric excess [d.e.] (S, 3R) and 52.5% d.e. (R, 3R), respectively). The behavior of the unsaturated (−)-menthyl ester substrate was also investigated with neutral diphosphine-rhodium(I) complexes containing symmetrical α, ω-bis(diphenylphosphino)alkanes {Ph2P(CH2)nPPh2} 6.6% d.e. (S, 3R) [n = 3]; 12.0% d.e. (R, 3R) [n = 4]; 7.2% d.e. (R, 3R) [n = 5]; and 7.4% d.e. (R, 3R) [n = 6]. Z-(−)-(1S, 2R, 4S)-bornyl-α-acetamidocinnamate was similarly studied: 49.8% (S, 2R)[(+)-(2S, 3S)-DIOP]; 64.1% d.e. (R, 2R) [(−)-(2R, 3R)-DIOP]; 4.9% d.e. (S, 2R) [n = 3]; 9.1% d.e. (R, 2R) [n = 4]; 13.6% d.e. (R, 2R) [n = 5]; and 12.0% d.e. (R, 2R) [n = 6]. 相似文献
12.
文章介绍了苯乙酮苯甲酰腙化合物的合成方法,以苯乙酮和苯甲酰肼为起始原料,经过一系列反应条件的筛选,如,催化剂种类、催化剂用量、反应时间及底物配比等条件,最终确定最佳反应条件,并经1H MNR对目标化合物结构确认。本合成操作简单且收率很高,符合绿色化学的发展方向。 相似文献
13.
不对称合成是当前有机合成中热门研究领域,利用手性金属络合物催化剂催化不对称硅氢化、烷基化,以烯烃、酮、亚胺、醛等合成手性醇、手性胺、手性酮等具有很好的工业应用前景。本文论述了手性金属络合物催化剂在不对称硅氢化反应及其在二烷基锌对醛的不对称烷基化反应中的应用。 相似文献
14.
Hyunseok Kim Young Kwan Kim Jun Hwan Shim Misook Kim Mijung Han Tom Livinghouse Phil Ho Lee 《Advanced Synthesis \u0026amp; Catalysis》2006,348(18):2609-2618
The thiophosphinic amide 2 was prepared in 68 % yield by the reaction of 2,2‐dimethyl‐1,3‐propanediamine with diisopropylchlorophosphine followed by the addition of sulfur. Attachment of the proligand 2 to zirconium was achieved by direct metalation with Zr(NMe2)4 in benzene‐d6 or toluene‐d8 to afford complex 3 via elimination of dimethylamine. The neutral Zr(IV) complex 3 has been shown to be an effective precatalyst for intramolecular alkene hydroaminations that provide cyclic amines in good to excellent yields. A variety of chiral ligands ( 20 , 22 , 24 , and 25 – 30 ) were prepared for asymmetric internal alkene hydroaminations. Metalation of chiral ligands to yttrium was accomplished with Y[N(TMS)2]3 in benzene‐d6 or toluene‐d8 to give complexes. Treatment of 7 with 5 mol % of 33 in benzene‐d6 (25 °C, 18 h) or toluene‐d8 (25 °C, 15 h) afforded 2,4,4‐trimethylpyrrolidine 14 in 95 % yield (61 % ee). 相似文献
15.
Boyapati M. Choudary Naidu S. Chowdari Karangula Jyothi Mannepalli L. Kantam 《Catalysis Letters》2002,82(1-2):99-102
MCM-41 anchored 1,4-bis(9-O-quininyl)phthalazine (MCM-(QN)2PHAL)-OsO4, is prepared for the first time and used in the heterogeneous asymmetric dihydroxylation of olefins to afford diols with good to excellent enantiomeric excesses in the presence of N-methylmorpholine N-oxide, K3Fe(CN)6 or molecular oxygen as cooxidants. 相似文献
16.
针对不同无机材料载体和固载方法,综述了近几年无机材料固载Mn(Salen)催化剂的研究进展。重点介绍了二氧化硅、分子筛、活性炭、溶胶凝胶固载手性Mn(Salen)催化剂的特点及性能,并对固载手性Mn(Salen)催化剂存在的问题和前景进行了分析。 相似文献
17.
Ziyong Jia Xiangkai Fu Yunfei Luo Huaizhi Zhang Xuemei Huang Hao Wu 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(2):415-422
Aluminium oligo-styrenyl phosphonate-hydrogen phosphate (AlSPP) was used as organic–inorganic hybrid support after chloromethylation,
and then with using different diamines as a reactive surface modifier. We realized the homogeneous chiral salen Mn(III) complex
axially immobilized on modified AlSPP by a covalent grafting method. The prepared heterogeneous salen Mn(III) complexes were
characterized by different techniques such as FT-IR, diffusion reflection UV–Vis, AAS, XPS, N2 volumetric adsorption, SEM, TEM and TG. The chiral salen Mn(III) complexes were immobilized onto the AlSPP through axial
coordination for the first time with m-CPBA/NMO as an oxidant system for asymmetric epoxidation of unfunctionalized olefins. The supported catalyst showed very
good performance in the asymmetric epoxidation of α-methylstyrene and indene. The catalyst could be easily recovered and reused
without significant loss of activity and enantioselectivity after nine cycles. This novel heterogeneous catalyst could be
efficiently used in large-scale reactions with the enantioselectivity being maintained at the same level, which offer great
possibilities for application in industry. 相似文献
18.
《Inorganic chemistry communications》2000,3(11):557-562
This paper describes the synthesis and spectroscopic study of a titanium(IV) silsesquioxane complex, which is heterogenised in the pores of an MCM-41 host material. Its immobilization is performed via chemical bonding, not by means of physical adsorption. As a linking molecule between the MCM-41 carrier and the silsesquioxane, (3-glycidyloxypropyl)trimethoxysilane is used. Characterization is performed by using nitrogen adsorption techniques, TGA, diffuse reflectance infrared spectroscopy (DRIFT) and ICP-MS. Also its catalytic activity towards the epoxidation of alkenes shows interesting results. 相似文献
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