共查询到20条相似文献,搜索用时 15 毫秒
1.
A new polymeric reagent, cross-linked poly(4-vinylpyridine) supported azide ion, [P4-VP]N3, was introduced as polymeric reagents for efficient and regioselective conversion of epoxides to azidohydrins in the presence of cross-linked poly(4-vinylpyridine) supported sulfuric acid, [P4-VP]H2SO4, as a solid proton source and as catalyst under solvent-free conditions. The advantages of this polymeric reagent over some of those reported in the literature are easy work-up procedure and regeneration of the reagent. 相似文献
2.
Anna M. Bauer Erin E. Ramey Kjersti G. Oberle Gretchen A. Fata Chloe D. Hutchison Christopher R. Turlington 《Tetrahedron letters》2019,60(43):151193
Oxygen atom transfer (OAT) reagents are common in biological and industrial oxidation reactions. While many heterogeneous catalysts have been utilized in OAT reactions, heterogeneous OAT reagents have not been explored. Here, cross-linked poly(4-vinylpyridine-N-oxide), called x-PVP-N-oxide, was tested as a heterogeneous OAT reagent and its oxidation chemistry compared to its molecular counterpart, pyridine-N-oxide. The insoluble oxidant x-PVP-N-oxide demonstrated comparable reactivity to pyridine-N-oxide in direct oxidation reactions of phosphines and phosphites in acetonitrile, but x-PVP-N-oxide did not react in other solvents. The polymer backbone of x-PVP-N-oxide, however, allowed for easy filtering and recycling in sequential oxidation reactions. In addition, x-PVP-N-oxide was tested as the stoichiometric oxidant in a copper-catalyzed OAT reaction to α-diazo-benzeneacetic acid methyl ester. The heterogeneous oxidant was much less reactive than pyridine-N-oxide, indicating that interaction with the metal catalyst was challenging. These results demonstrated a proof-of-concept that recyclable, polymer-supported OAT reagents could be a viable OAT reagents in direct oxidation reactions without metal catalysts. 相似文献
3.
Byoung Se Lee 《Tetrahedron》2005,61(12):3081-3086
Eight cross-linked poly(4-vinylpyridine/styrene) (P/S) resins (as beads) were prepared by radical suspension polymerization. Ytterbium triflate was immobilized in the range of 0.10-0.24 mmol/g by mixing with the P/S resins. The ytterbium triflate-immobilized P/S resins exhibited good activity in two Lewis acid-catalyzed reactions. Low pyridine containing resins were recycled with no loss of activity, while a slight loss of activity was observed with the higher pyridine containing resins. 相似文献
4.
Taterao M. Potewar 《Tetrahedron letters》2007,48(10):1721-1724
An efficient synthesis leading directly to 1-substituted-1H-1,2,3,4-tetrazoles from easily available amines and sodium azide in stoichiometric proportions using a room-temperature ionic liquid, namely, 1-n-butylimidazolium tetrafluoroborate in excellent yields is described. The inherent Brønsted acidity and high polarity of the IL results in a significant enhancement in the reaction rate. 相似文献
5.
Mohammad Ali Karimi Zarchi Fatemeh Nazem 《Journal of the Iranian Chemical Society》2014,11(6):1731-1742
Cross-linked poly(4-vinylpyridine)-supported copper sulfate, [P4-VP]CuSO4 as a green and recyclable, heterogeneous catalyst in the presence of sodium ascorbate (NaAsc), is reported for the regioselective synthesis of 1,4-disubstituted-1,2,3-triazoles from benzyl halides, sodium azide and terminal alkyne in water/t-BuOH (1/1:V/V) at 70 °C. Various alkyl halides and benzyl halides, with electron-withdrawing groups as well as electron-donating groups, were used for synthesis of various 1,4-disubstituted-1,2,3-triazoles in high yields. The present procedure offers as short reaction time and simple reaction work up. This catalyst can be recovered by simple filtration and recycled several consecutive runs without any loss of its efficiency. 相似文献
6.
Kei Matsuzaki Tetsuyuki Matsubara Taiichi Kanai 《Journal of polymer science. Part A, Polymer chemistry》1977,15(7):1573-1583
In order to determine the stereoregularity of poly(4-vinylpyridine), 4-vinylpyridine-β,β-d2 was synthesized from 4-acetylpyridine. The 1H-NMR spectra of the deuterated and nondeuterated polymers were measured and analyzed. From the 1H-NMR spectra of poly(4-vinylpyridine-β,β-d2), triad tacticity can be obtained, while the 1H-NMR spectra of nondeuterated poly(4-vinylpyridine) give the fraction of isotactic triad. The 13C-NMR spectra of poly(4-vinylpyridine) were also observed, and the spectra of C4 carbon of polymers were assigned by the pentad tacticities. The fraction of isotactic triad of poly(2-vinylpyridine) and poly(4-vinylpyridine) obtained under various polymerization conditions were determined. The radical polymerization and anionic polymerizations with phenylmagnesium bromide and n-butyllithium as catalysts of 4-vinylpyridine gave atactic polymers. 相似文献
7.
Jalal Albadi Farhad Shirini Jafar Abasi Nezam Armand Tayebeh Motaharizadeh 《Comptes Rendus Chimie》2013,16(5):407-411
Poly(4-vinylpyridine)-supported copper iodide is reported as a green, efficient and recyclable catalyst for the synthesis of coumarin derivatives by the Pechmann reaction under solvent-free conditions. This catalyst can be recovered by simple filtration and recycled up to eight consecutive runs without any loss of their efficiency. 相似文献
8.
Hiroyuki Nishide Jichio Deguchi Eishun Tsuchida 《Journal of polymer science. Part A, Polymer chemistry》1977,15(12):3023-3029
Poly(4-vinylpyridine) (PVP) was crosslinked with 1,4-dibromobutane with a metal ion as template. The adsorption behavior of copper, cobalt, zinc, and cadmium ions on the obtained resin (DBQP) was studied. The DBQP resin prepared with a metal ion as template preferentially adsorbed the metal ion used as template. The stability constant of the copper complex of DBQP was largest for the DBQP resin prepared with a copper ion as template, which was due to its large entropy change for the complexation. 相似文献
9.
《Journal of organometallic chemistry》2007,692(20):4402-4406
A new catalytic system based on the palladium supported on poly(N-vinylimidazole) or poly(N-vinylimidazole-co-N-vinylcaprolactam) was investigated. High efficiency of the catalyst along with its recycling ability was demonstrated in the Mizoroki–Heck reaction. 相似文献
10.
We extend the application of polymer brush to the synthesis of silver nanoparticles. Polymer brushes can efficiently prevent the aggregation of the prepared nanoparticles and allow the tailored synthesis of Ag nanoparticles. 相似文献
11.
12.
J.S. Yadav B.V. Subba Reddy G.G.K.S. Narayana Kumar T. Swamy 《Tetrahedron letters》2007,48(12):2205-2208
Iodine is found to be an efficient reagent for the coupling of homoallylic alcohols with aldehydes under mild conditions to produce 4-iodotetrahydropyran derivatives in excellent yields in a short reaction time with high selectivity. The use of iodine makes this procedure simple, convenient and cost-effective. 相似文献
13.
2,3-Dihydroquinazolin-4(1H)-one derivatives are synthesized via a one-pot,three component reaction of isatoic anhydride and an aromatic aldehyde with ammonium acetate or primary amine catalyzed by silica-bonded N-propylsulfamic acid(SBNPSA) in refluxing ethanol. 相似文献
14.
A simple and efficient protocol developed for the synthesis of 5-substituted 1H-tetrazole derivatives through [2+3] cycloaddition reaction between benzonitriles and sodium azide using diisopropylethylammonium acetate as a recyclable reaction medium is described. The reactions proceed well at 80?°C and provide the corresponding tetrazoles in good to excellent yields (up to 94% yield). Developed method has notable advantages, such as simple and mild conditions, easy workup, reusability with consistent catalytic activity, and safer alternative to hazardous, corrosive conventional Lewis acid catalysts. 相似文献
15.
AbstractA simple, efficient, and metal-free methodology for the preparation of 2-mercaptobenzothiazole and derivatives in excellent yields via microwave-assisted pathway is reported. Our condition provides a convenient protocol for the synthesis of a diverse collection of 2-mercaptobenzothiazoles and 6-(4-substituted-1H-1,2,3-triazol-1-yl)-2-mercaptobenzothiazoles with a very simple purification process. This report provides an alternative protocol for fast access to the wide range of compounds for sequence synthesis and biological studies. 相似文献
16.
以聚4-乙烯基吡啶(PVP)为有机组分,正硅酸乙酯(TEOS)为无机组分,利用sol-gel方法制得PVP/SiO~2纳米杂化材料,以此为载体制备了杂化材料负载单茂钛催化剂。利用XPS和IR分析了载体与CpTiCl~3的结合方式,确认对苯乙烯聚合有两种活性中心,苯乙烯聚合结果表明在50℃左右间规度达到最大;在70℃,n(Al)/n(Ti)=1500时活性最高可达1.09×10^6gPS/(molTi·h),GPC结果表明产物分子量分布呈双峰分布。 相似文献
17.
A general procedure for the synthesis of a large variety of compounds comprising an alpha, beta,-unsaturated carbonyl functionality was developed. The use of one-pot cascade synthesis with (triphenylphosphora-nylidene)ethenone as a versatile reagent for various formations including heterocycles of different ring sizes and unsaturated amides in combination with microwave dielectric heating is described. The method was used to synthesize a small library of unsaturated amides. 相似文献
18.
A glassy-carbon electrode modified with a ruthenium-containing inorganic film was used for the flow-injection determination of As(III). The linear working range was 5-100 muM, and the detection limit was 300 pg. The response was reproducible for periods of several days. A glassy-carbon electrode modified by adsorption of a quaternized poly(4-vinylpyridine) film impregnated with hexachloroiridate(II and III) was used for the oxidation of nitrite. The calibration graphs were non-linear and varied from day to day, and the peak widths were broad. Nitrite determination at a platinum electrode modified by adsorption of iodine gave results analogous to the As(III) study; however, an overlayer of quaternized poly(4-vinylpyridine) decreased the sensitivity. 相似文献
19.
L. A. Pavlova V. A. Davankov G. I. Timofeeva M. M. Il’in Jr. I. V. Blagodatskikh O. V. Sinitsyna V. V. Matveev A. E. Chalykh 《Polymer Science Series A》2013,55(10):603-613
Hydrophilic ionic nanosponges with quaternary pyridinium groups are synthesized on the basis of 4-vinylpyridine and its polymer. Their synthesis relies on the use of bior polyfunctional agents alkylating pyridine in dilute solutions in a thermodynamically good solvent. Individual intramolecularly crosslinked soluble macromolecules with molecular masses from 6000 to 400000 are prepared at various degrees of dilution. 1,4-Bis(halomethyl)benzenes, p-vinylbenzyl chloride, and poly(vinylbenzyl chloride) are used as N-alkylating agents. The shapes and sizes of macromolecules are determined via the methods of diffusion, sedimentation, viscometry, dynamic light scattering, atomic force microscopy, and transmission electron microscopy. 相似文献
20.
1-Substituted-2,5(4H)-piperazinediones are prepared by the Michael addition of acrylonitrile and methyl-acrylate and glycylglycine, DL-alanyl-DL-alanine and DL-alanyl-DL-phenylalanine followed by cyclohydration in refluxing xylenes. 相似文献