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171.
172.
Vijay Kumar Singh Abhishek Maurya Neha Kesharwani Payal Kachhap Sweta Kumari Arun Kumar Mahato 《Journal of Coordination Chemistry》2018,71(4):520-541
Schiff base-functionalized chloromethylated polystyrenes, PS-[Ae-Eol] (I), PS-[Hy-Eda] (II) and PS-[HyP-Eda] (III), were synthesized by reacting 2-(2-aminoethoxy)ethanol (Ae-Eol), N-(2-hydroxyethyl)ethylenediamine (Hy-Eda), and N-(2-hydroxpropyl)ethylenediamine (HyP-Eda) with oxidized chloromethylated polystyrene. Oxidized chloromethylated polystyrene (PS-CHO) was prepared by oxidation of chloromethylated polystyrene (PS) with sodium bicarbonate in DMSO. By reacting DMSO solution of [VO(acac)2] with polymer-anchored Schiff base ligands I, II, and III, vanadium(IV) complexes PS-[VIVO(Ae-Eol)] (1), PS-[VIVO(Hy-Eda)] (2), and PS-[VIVO(HyP-Eda)] (3) were prepared. Structure and bonding of I, II, and III as well as corresponding vanadium complexes 1, 2, and 3 were confirmed by FT-IR, UV–vis spectroscopy, SEM, EDX, AAS, TGA, EPR, etc. Polymer-anchored vanadium(IV) complexes 1, 2, and 3 show, efficient catalysis toward oxidation of styrene, cyclohexene, allylbenzene, and cis-cyclooctene in the presence of hydrogen peroxide. Optimized reaction conditions for the oxidation of these alkenes was achieved by changing various reaction parameters (like amount of catalyst, amount of oxidizing agent, volume of solvent, etc.). Polymer-grafted 1, 2, and 3 can be reused multiple times without depletion of their activity. 相似文献
173.
The current study deals with the preparation of novel crosslink transparent poly(ester-urethane-acrylate)/methyl methacrylate (TPEUMA) copolymers and the effect of hydroxyl terminated aromatic polyester (PEs) was also investigated. The properties of TPEUMA were investigated in terms of double bond concentration, polymerization shrinkage, abrasive wear analysis and chemical resistance. The volume shrinkage decreased due to the significant reduction in the concentration of double bonds. The first two effects reflect in lowering the abrasive wear resistance properties at room temperature, while the larger chain length between crosslink decreases the hardness. Decrease in polymerization shrinkage shows more condensed microstructure which was revealed by the abrasive wear rate of TPEUMAs due to hydrogen bonding near to crosslink point. Increase in the chain length of PEs, decreases the glass transition temperature of TPEUMA copolymer which results in loose microstructure. Worn surface were studied using scanning electron microscope to give insight on the wear mechanism of TPEUMA crosslink. It can be suggested from the present study that this copolymer can be used for a broad range of optical applications. 相似文献
174.
Sushil K. Maurya 《Tetrahedron letters》2006,47(19):3307-3310
An efficient synthesis of spiroannulated dihydroisobenzofurans is achieved using easily accessible carbohydrate-derived furanyl propargyl ethers via an AuCl3 promoted intramolecular Diels-Alder (IMDA) reaction. The scope of the spiroannulation protocol was demonstrated using a diverse range of pentofuranosyl, hexofuransoyl and hexopyranosyl derived substrates in order to synthesize spiroannulated dihydroisobenzofurans. The reaction is high yielding, moisture tolerant, fast and uses only a catalytic amount of AuCl3. 相似文献
175.
176.
Reaction of 2-(-hydroxymethyl)benzimidazole or 2-(-hydroxyethyl)benzimidazole (LH) with the peroxovanadium(V) species, generated in situ by stirring V2O5, KOH and 30% aqueous H2O2, gives the corresponding complexes of formula K[VO(O2)L2]. Similar peroxo species of molybdenum and tungsten generated by stirring MoO3 or WO3·H2O with an excess of 30% aqueous H2O2 readily react with 2-(-hydroxyethyl) benzimidazole in aqueous EtOH to give the peroxo complexes [MO(O2)L2] (M=Mo or W). The dioxo complexes of general formula [MO2L2] have also been isolated by the reaction of [MoO2(acac)2] or [WO2- (acac)2] (acacH=acetylacetone) with the above ligands and with 2-(-hydroxybenzyl)benzimidazole. The dioxo complexes are white, whereas peroxo complexes are light yellow to orange. The peroxo complexes generally decompose in two steps: (i) the decomposition of the peroxo group and (ii) the decomposition of the alkyl/aryl group followed by decomposition of the complete ligand. On the other hand, decomposition of the dioxo complexes follows only in a later step. All the peroxo complexes exhibit three i.r. active vibrational modes at ca. 860cm–1, 760cm–1 and 600cm–1, characteristic of the 2-coordinated peroxo group. The dioxo complexes are dominated by the presence of two sharp bands in the 900cm–1 region due to sym(O=M=O) and asym(O=M=O) modes. The (C=N) (ring) and (OH) shifts have also been measured in order to locate the coordination sites of the ligands. A broad band at ca. 400nm in the peroxovanadium(V) complexes, while the absorption at ca. 350nm in the peroxomolybdenum(VI) and tungsten(VI) complexes is assigned to the peroxo-metal charge transfer band. 相似文献
177.
M. R. Maurya S. J. J. Titinchi S. Chand I. M. Mishra 《Journal of molecular catalysis. A, Chemical》2002,180(1-2):201-209
Cr(III), Fe(III), Bi(III), Ni(II) and Zn(II) complexes of N,N′-bis(salicylidene)propane-1,3-diamine (H2salpn) encapsulated in Y-zeolite were prepared by flexible ligand method. These complexes were characterized by chemical and thermal analyses, FT-IR and electronic spectral studies and their XRD pattern. The encapsulated materials are active catalysts for the decomposition of hydrogen peroxide and for the oxidation of phenol using H2O2 as oxidant with good selectivity. 相似文献
178.
The stereoselective synthesis of spiroannulated cyclopentenones by the Pauson-Khand reactions on hexose and pentose derived enynes was achieved under carbon monoxide free conditions using a stoichiometric quantity of Co2(CO)8. The cobalt complex of the alkyne was cleaved using dimethoxyethane-acetonitrile at 85 °C to furnish spiroannulated cyclopentenones in 75-94% yields. 相似文献
179.
Summary Several new seven-coordinated dioxomolybdenum(VI) heterochelates, [MoO2(AA)(BBB)], where AA = bidentate ligand = ethylenediamine, 2-aminoethylpyridine,o-pheny-lenediamine,o-phenanthroline or 2,2-dipyridyl; BBB = tridentate ligand (the Schiff base derived from benzoylhydrazide and salicylaldehyde), have been synthesized and characterized by elemental analysis, molar conductance, molecular weight, i.r. spectra and magnetic susceptibility measurements. The principle of coordination number expansion of a six coordinate homochelate, [MoO2(H2O)(BBB)] was used to prepare the complexes, which are nonelectrolytes, monomers and diamagnetic. The i.r. spectral data reveal that they possess acis-MoO2 structure. The sym(OMoO) and asym(OMoO) shifts and the difference between sym(OMoO) and asym(OMoO) have been related to an increase in electron density at the molybdenum atom therein. 相似文献
180.
Bakers’ yeast efficiently catalyzes the unsymmetrical Hantzsch reaction through a four-component coupling of aldehydes, β-ketoesters, dimedone and ammonium acetate to form polyhydroquinoline derivatives in good to excellent yields. 相似文献