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41.
Theoretical calculations were performed on the [3+2] cycloaddition (32CA) reaction of nitrile oxide and N-vinylpyrrole. The regiochemistry of the reaction has been studied based on potential energy surface analysis and global and local reactivity indices of the reactants. The global electron density transfer (GEDT) calculations at the possible transition states revealed that this cycloaddition has a nearly non-polar character. The ELF topological analyses of the selected structures involved in the intrinsic reaction coordinate (IRC) of TS1a suggests that this 32CA reaction takes place through a two-stage one-step mechanism. 相似文献
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In this research, green synthesis of imidazo[1,2-a]pyridines in the presence of calix[n]arenes-SO3H as a Brønsted acid catalyst and surfactant is described. Using of calix[n]arenes in water provided a hydrophobic cavity that successfully carried out the synthesis reactions at short times with high yields. This catalyst system is recoverable with a simple extraction using an organic solvent and reusable for at least for 5 cycles without any losses of its activity. 相似文献
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ABSTRACTDFT and MP2 calculations were used to determine the nature of non-covalent tellurium–π interactions in R2Te???C6H6 (R = H, F, Cl, CH3) and C4H4Te???C6H6 systems. The results showed that the strength of Te···π interaction follows the order F2Te > Cl2Te > tellurophene > H2Te > Me2Te. Also, the F2X···π system complexes (X = Te or Se, π system = C6F6, C6(CH3)6, Cr(C6H6)2 and coronene) were studied for investigating the direction of charge flow in Te···π interaction. The obtained data expressed that the existence of electron withdrawing group on Te atom increases the strength of Te???π interaction while the fluorine atoms on benzene ring decrease it. The breakdown of ΔEint in the R2Te···C6H6 (R = H, F, Cl, CH3) and C4H4Te···C6H6 systems using two dispersion corrected DFT methods showed that when the R group on divalent tellurium atom is an electron withdrawing substituent, the contribution of ΔEelstat and ΔEorb in total interaction energy increases and the value of ΔEint is relatively large. The present data also showed that the intermolecular Te···π interactions are slightly stronger than corresponding Se···π interactions. 相似文献
44.
Novel species of soluble thermally stable poly(keto ether ether amide)s: preparation,characterization, and properties
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Elahe Sabbaghian Shahram Mehdipour‐Ataei Seyedmehrdad Jalilian Mahshid Esfahanizadeh Ali Mohammad Salehi Fardin Khodabakhshi Elham Jalalian 《先进技术聚合物》2015,26(1):1-9
A new diamine containing one keto and four ether groups was prepared through a three‐step reaction: first, hydroquinone was reacted with 1‐fluoro‐4‐nitrobenzene and 4‐(4‐nitrophenoxy) phenol was obtained. The next step was reduction of nitro group to amino group in which 4‐(4‐aminophenoxy) phenol was prepared. In the final step, the new diamine named as bis(4‐(4‐(4‐aminophenoxy)phenoxy)phenyl) methanone was synthesized through reaction of the later compound with 4,4′‐difluoro benzophenone. All prepared materials were fully characterized by spectroscopic methods and elemental analysis. Novel species of poly(keto ether ether amide)s were synthesized via polymerization reaction of the diamine with different diacid chlorides including terephthaloyl chloride, isophthaloyl chloride, and adipoyl chloride. All polyamides were characterized, and their properties such as thermal behavior, thermal stability, solubility, viscosity, water uptake, and crystallinity were investigated and compared together. The glass transition temperatures of the polymers were about 204–232°C, and their 10% weight losses were in the range of 396–448°C. Polymers showed high thermal stability and enhanced solubility that mainly resulted from incorporation of the diamine structure containing keto, ether, and aromatic units into polyamide backbones. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Colloidal suspensions containing magnetic nanoparticles placed in appropriate carrier liquids present strong magnetic dipoles. These suspensions, in general, exhibit normal liquid behaviour coupled with super paramagnetic properties. This leads to the possibility of remotely controlling the flow of such liquids with a moderate-strength external magnetic field. In this study, we numerically investigate the viability of controlling and steering a base-fluid with magnetic-sensitive nanoparticles into randomly structured fibrous porous media. Three dimensional flow simulations are performed using the lattice Boltzmann method. The simulation results for the flow front are presented, and the effect of the magnetic field strength on the rate of ferrofluid penetration is discussed. It is shown that the porosity of the porous medium and the size of the fibres have a strong effect on the ferrofluid penetration rate. 相似文献
47.
Sayed Mehdi Ghoreishi Mohsen Behpour Mahshid Golestaneh 《International journal of environmental analytical chemistry》2013,93(12):1403-1416
In this paper, a simple, convenient and sensitive electrochemical method has been developed for the determination of C.I. Direct Red 80. A gold nanoparticle modified carbon paste electrode was fabricated and used for study and sensitive determination of Direct Red 80 by cyclic voltammetry and differential pulse voltammetry. The overall analysis involved a two-step procedure: an accumulation step under open-circuit conditions, followed by voltammetric measurements of Direct Red 80 in a 0.1?M phosphate buffer solution at pH?=?3.0. The experimental conditions, such as the medium, pH and accumulation time, were optimised. The oxidation peak current was proportional to the concentration of Direct Red 80 from 5.0?×?10?8 to 5.0?×?10?7?M and 5.0?×?10?7 to 3.0?×?10?6?M, and the detection limit was 1.15?×?10?8?M (S/N?=?3). The proposed method was used to detect Direct Red 80 in natural water and sewage with good accuracy. 相似文献
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Rahim Hekmatshoar Sanaz Souri Mahshid Rahimifard Farnoosh Faridbod 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2827-2833
Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dimethyl acetylenedicarboxylate(DMAD) by substituted phenols lead to vinyl triphenylphosphonium salts, which undergo aromatic electrophilic substitution reaction with a phenolate conjugate base to produce 4-carboxymethyl coumarins in fairly highly yields. 相似文献
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Issa Yavari Mahshid Nikpoor-Nezhati Shoaleh Dehghan 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):485-494
Ab initio molecular orbital calculation at HF/6-31G*, HF/6-31G**, HF/6-311G**, HF/6-311++G**, RMP2-FC/6-31G*, and B3LYP/6-31G* levels of theory for geometry optimization and MP4(SDQ)/6-31G* for a single-point total energy calculation are reported for phosphinine and 13 isophosphinines 7-19 . Isomers 7-11 with an allenic system are calculated to be 8-18 kcal mol m 1 more stable than structures 12-17 with an acetylenic moiety. The calculated energy difference (66.19 kcal mol m 1 ) between phosphinine and the most stable isophosphinine (1-phospha-1,2,4-cyclohexatriene, 10 ) is smaller than the difference (78.96 kcal mol m 1 ) between benzene and the most stable isobenzene (cyclohexa-1,2,4-triene, 2 ). The isophosphinines 18 and 19 , with a butatriene moiety, are calculated to be the least stable isomers. 相似文献
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Mahshid Sattari Gholam Hossein Rounaghi Behjat Deiminiat Massoumeh Mohajeri 《Russian Journal of General Chemistry》2014,84(3):571-577
The stability constant (log K f) and the thermodynamic parameters (free energies, enthalpies, and entropies) of the complexation of Co2+ cation with 15-crown-5 (15C5) in acetonitrile-methanol (AN/MeOH), acetonitrile-nitrobenzene (AN/NB), acetonitrile-dichloromethane (AN/DCM) and acetonitrile-1,2-dichloroethane (AN/DCE) binary solvent solutions were calculated from the experimental conductance data at different temperatures. The complexation behavior of the crown ether used in these media was discussed in view of the estimated parameters. In all solvent systems, 15-crown-5 formed a 1: 1 complex with Co2+ cation. The stability order of (Co-15C5)2+ complex in the binary mixed solvents at 25°C was found to be: AN/NB > AN/DCM ≈ AN/DCE > AN/MeOH. In most cases, a non-linear relationship was observed for changes of log K f of (Co-15C5)2+ complex versus the composition of the binary mixed solvent systems. The experimental results show that the standard thermodynamic parameters of the complexation process change with the nature and composition of the binary solvent solutions. 相似文献