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51.
52.
Manirul Islam Sanchita Mondal Mobarak Manir Anupam Singha Roy Paromita Mondal Dildar Hossain 《中国化学》2010,28(10):1810-1820
Polymer anchored Cu(II) Schiff base complexes have been prepared and characterized by using scanning electron microscope (SEM), elemental analysis, atomic absorption spectroscopy (AAS), thermogravimetric analysis (TGA), spectrometric methods like diffuse reflectance spectra of solid (DRS) and fourier transform infrared spectroscopy (FTIR). These catalysts show excellent catalytic activity in the O‐arylation reaction of aryl halides with phenol in acetonitrile using Cs2CO3 at 70°C under an open air condition to give diaryl ethers in high yields. The effects of various parameters such as solvent, catalyst from different copper salt and base on the reaction system have been studied. The reaction is applicable to a wide variety of substituted aryl halides and phenols with different steric and electronic properties. These catalysts are recovered by simple filtration and the reusability experiments show that these catalysts can be used five times without much loss in the catalytic activity. 相似文献
53.
The effect of CuSCN as a catalyst in atom‐transfer radical polymerization (ATRP) was investigated. CuSCN can successfully be used for the ATRP of MMA. Substituted bipyridines as well as imines can be used to stabilize the copper complex in solution. CuSCN induces faster polymerization compared to CuBr and CuCl when tosylchloride is used as the initiator. However, the polydispersity is larger than that obtained in the cases of CuCl and CuBr. 相似文献
54.
Poly(methyl methacrylate) (PMMA) was synthesized via atom transfer radical polymerization (ATRP). As a catalyst copper(I)thiocyanate (CuSCN) was used with N-n-pentyl-2-pyridylmethanimine as a ligand. Infrared spectroscopy and matrix assisted laser desorption ionization time-of-flight mass spectrometry were used to characterize the synthesized polymers. From this it was clear that at least to some extent thiocyanate was present as end groups of the PMMA chains. This observation is discussed in view of a phenomenon called halogen exchange, which has been reported before for bromine/chlorine exchange in ATRP. 相似文献
55.
Sk. Manirul Islam Sanchita Mondal Paromita Mondal Anupam Singha Roy Noor Salam Sumantra Paul Manir Mobarak 《Transition Metal Chemistry》2011,36(7):699-706
A polymer-anchored Pd(II) complex has been prepared and characterized using scanning electron microscopy, elemental analysis,
atomic absorption spectroscopy and FTIR. The catalyst shows excellent catalytic activity in the liquid-phase hydrogenation
of substituted nitrobenzenes at normal pressure of hydrogen gas at 25 °C in DMF medium. We have also studied the liquid-phase
hydrogenation of other organic substrates such as alkenes, alkynes, aromatic aldehydes, etc. The influences of various parameters
such as amount of catalyst, concentration of substrate, temperature and solvent have been studied. The catalyst can be used
five times without much loss in activity. 相似文献
56.
Sk.Manirul Islam Sanchita Mondal Paramita Mondal Anupam Singha Roy K. Tuhina Noor Salam Manir Mobarak 《Journal of organometallic chemistry》2012,696(26):4264-4274
A simple and industrially viable protocol for C–N and C–O coupling was reported here. The polymer supported heterogeneous copper catalyst was prepared from chloromethyl polystyrene using a simple procedure. O-Arylation of substituted phenols with various aryl halides was achieved using this copper catalyst in DMSO medium. This heterogeneous copper catalyst, also efficiently works for the N-arylation of N–H heterocycles with aryboronic acids in methanol. This catalyst was also effective in amination reaction of primary amines with aryl halides as well as arylboronic acids in DMSO medium. The effects of solvent, base and temperature for the O-Arylation and amination reactions were reported. Further, the catalyst can be easily recovered quantitatively by simple filtration and reused up to several times without sufficient loss of its catalytic activity. 相似文献
57.
Roy Sourav Singha Sarkar Sriparna Chakraborty Debashis 《Journal of inclusion phenomena and macrocyclic chemistry》2021,100(1-2):1-36
Journal of Inclusion Phenomena and Macrocyclic Chemistry - In the twenty-first century, one of the central focus of polymer research in academia and industries is directed towards the design of... 相似文献
58.
Vítor H. Fernandes Preeyanuch Honyam Teresa M. Quinteiro Boorapa Singha 《Semigroup Forum》2014,89(1):77-104
Let X be a finite or infinite chain and let \({\mathcal{O}}(X)\) be the monoid of all endomorphisms of X. In this paper, we describe the largest regular subsemigroup of \({\mathcal{O}}(X)\) and Green’s relations on \({\mathcal{O}}(X)\) . In fact, more generally, if Y is a nonempty subset of X and \({\mathcal{O}}(X,Y)\) is the subsemigroup of \({\mathcal{O}}(X)\) of all elements with range contained in Y, we characterize the largest regular subsemigroup of \({\mathcal{O}}(X,Y)\) and Green’s relations on \({\mathcal{O}}(X,Y)\) . Moreover, for finite chains, we determine when two semigroups of the type \({\mathcal {O}}(X,Y)\) are isomorphic and calculate their ranks. 相似文献
59.
A novel polystyrene-supported palladium(II) complex, an excellent and recyclable catalyst, was synthesized for Sonogashira reactions. The present complex shows high catalytic activity for Sonogashira cross-coupling reaction of aryl halides with phenylacetylene under phosphine-free and copper-free reaction conditions in aqueous (DMF–H2O) medium. The catalyst could be reused for at least six reaction cycles with almost unchanged catalytic properties.
60.
Ashish Kumar Singha Deb B. N. Mohanty P. Ilaiyaraja K. Sivasubramanian B. Venkatraman 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(2):1161-1169
Multi-walled carbon nanotubes (MWCNTs) were functionalized with diglycolamide (DGA) through chemical covalent route. The adsorption behavior of the DGA-functionalized-MWCNTs (DGA-MWCNTs) towards thorium from aqueous solution was studied under varying operating conditions of pH, concentration of thorium, DGA-MWCNTs dosages, contact time, and temperature. The effective range of pH for the removal of Th(IV) is 3.0–4.0. Kinetic data followed a pseudo-second-order model. The equilibrium data were correlated with the Langmuir, Freundlich, Dubinin-Radushkevich and Temkin models. The equilibrium data are best fitted with Langmuir model. The equilibrium Th(IV) sorption capacity was estimated to be 10.58 mg g?1 at 298 K. The standard enthalpy, entropy, and free energy of adsorption of the thorium with DGA-MWCNTs were calculated to be 8.952 kJ mol?1, 0.093 kJ mol?1 K?1 and -18.521 kJ mol?1 respectively at 298 K. The determined value of sticking probability (0.072) and observed kinetic and isotherm models reveal the chemical adsorption of thorium on DGA-MWCNTs. 相似文献