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961.
Habibi Khorassani SM Ebrahimi A Maghsoodlou MT Shahraki M Price D 《The Analyst》2011,136(8):1713-1721
In the present work, for the first time, investigation of the initial fast step of reaction between 1,1,1-trichloro-3-methyl-3-phospholene (TCMP) and methanol was studied under a dry inert atmosphere by a newly constructed CSF apparatus by means of a further development in the configuration of the previous stopped-flow spectrophotometer (SFS). Hence, it was necessary to make many changes to the stopped-flow apparatus: replacement of the spectrophotometer amplifier with a conductance amplifier and the use of a conductivity cell to replace the optical one. The conductivity cell was made of polyethylene capillary tube (1 mm internal diameter; i.d.) and its inside dimensions were 1 mm i.d. × 3 mm long. Two tube electrodes which are made of stainless steel (0.8 mm i.d. × 14 mm long) were fixed at opposite ends of the observation cell and their outer surfaces were connected to the conductivity bridge amplifier by the two lead wires. The mixer was a 3-way Teflon valve and the distance between the mixer and the end of the observation cell was 30 mm. For each run, at least 24 μL of solution was required for a typical trace with a dead time of about 5 ms. Because of the extreme sensitivity of TCMP to moisture, the stopped-flow (CSF) apparatus was used inside a glove bag under a dry nitrogen atmosphere. Kinetic parameters for pseudo first-order reaction involving k(obs) = 30 s(-1) at 22 °C and activation energy E(a) = 13.55 KJ mol(-1) were successfully calculated for the initial fast step of the reaction between TCMP and methanol at 22 °C. 相似文献
962.
High-speed and scalable nickel-catalyzed cross-coupling of arylboronic acids with aryl carbamates and sulfamates is achieved by using sealed-vessel microwave processing. 相似文献
963.
Hazem Ali Attia Karem Mahmoud Ewis Ibrahim Hamdy Abd Elmaksoud Mostafa A. M. Abdeen 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(13):2063-2070
The steady magnetohydrodynamic (MHD) flow of an incompressible viscous non-Newtonian power law fluid above an infinite rotating porous disk with heat transfer is studied. A uniform magnetic field is applied perpendicularly to the plane of the disk and a uniform injection or suction is applied through the surface of the disk. Numerical solutions of the nonlinear differential equations which govern the hydromagnetic and heat transfer are obtained. The effects of characteristics of the non-Newtonian fluid, the magnetic field parameter and the suction or injection velocity on the velocity and temperature distributions are considered. 相似文献
964.
Mostafa Kiamehr Firouz Matloubi MoghaddamVolodymyr Semeniuchenko Alexander VillingerPeter Langer Viktor O. Iaroshenko 《Tetrahedron》2012,68(47):9685-9693
The reaction of thiooxindoles with various 2- and 3-substituted pyridinium salts afforded a variety of functionalized thiazocinoindoles. The products have been prepared in good to excellent yields by regioselective dinucleophilic C/S-cyclocondensation of thiooxindoles with pyridinium salts. 相似文献
965.
Akbar Bagheri Mohammad Behbahani Mostafa M. Amini Omid Sadeghi Atieh Tootoonchi Zohreh Dahaghin 《Mikrochimica acta》2012,178(3-4):261-268
We present a study on the application of magnetic nanoparticles (MNPs) prepared from Fe3O4 and functionalized with pyridine as an adsorbent for the solid-phase extraction of trace quantities of Pd(II) ion. The pyridine group was immobilized on the surface of the MNPs by covalent bonding of isonicotinamide. The modified MNPs can be readily separated from an aqueous solution by applying an external magnetic field. Effects of pH, the amount of functionalized MNPs, extraction time, type and quantity of eluent, desorption time, break-through volume and interfering ions on the extraction efficiency were optimized. The amount of Pd(II) was then determined using FAAS. Under the optimized conditions, the detection limit and preconcentration factor are 0.15?μg?L-1 and 196, respectively, and the relative standard deviation (at 20?μgL?1; for n?=?10) is 3.7?%. The method had a linear analytical range from 1 to 80?μg?L-1 and was applied to determine Pd(II) in spiked tape water and soil. Figure
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966.
Minoo Dabiri Peyman Salehi Mahboobeh Bahramnejad Mostafa Baghbanzadeh 《Monatshefte für Chemie / Chemical Monthly》2012,55(23):109-112
Abstract
1-Methylimidazolium trifluoroacetate ([Hmim]TFA) is reported as a cost-effective catalyst for a simple and environmentally benign hetero-Michael reaction. [Hmim]TFA works both as reaction medium and catalyst. The reaction is applicable to various aromatic sulfur and nitrogen nucleophiles. This method has advantages such as high yields, short reaction time, and simple workup. The catalyst could be recycled several times without any loss of activity. 相似文献967.
Baghbanzadeh M Skapin SD Orel ZC Kappe CO 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(18):5724-5731
A rapid, microwave-assisted hydrothermal method has been developed to access ultrafine ZnO hexagonal microrods of about 3-4 μm in length and 200-300 nm in width by using a 1:5 zinc nitrate/urea precursor system. The size and morphology of these ZnO materials can be influenced by subtle changes in precursor concentration, solvent system, and reaction temperature. Optimized conditions involve the use of a 1:3 water/ethylene glycol solvent system and 10 min microwave heating at 150 °C in a dedicated single-mode microwave reactor with internal temperature control. Carefully executed control experiments ensuring identical heating and cooling profiles, stirring rates, and reactor geometries have demonstrated that for these preparations of ZnO microrods no differences between conventional and microwave dielectric heating are observed. The resulting ZnO microrods exhibited the same crystal phase, primary crystallite size, shape, and size distribution regardless of the heating mode. Similar results were obtained for the ultrafast preparation of ZnO nanoparticles with diameters of approximately 20 nm, synthesized by means of a nonaqueous sol-gel process at 200 °C from a Zn(acac)(2) (acac=acetylacetonate) precursor in benzyl alcohol. The specific role of microwave irradiation in enhancing these nanomaterial syntheses can thus be attributed to a purely thermal effect as a result of higher reaction temperatures, more rapid heating, and a better control of process parameters. 相似文献
968.
Ali Hossein Kianfar Mostafa Kazemi Boudani Mahmoud Roushani Mojtaba Shamsipur 《Journal of the Iranian Chemical Society》2012,9(4):449-453
The new [UO2L(CH3OH)] [where L?=?bis(salicylaldehyde)2,6-diiminopyridine (L1), bis(5-methoxysalicylaldehyde)2,6-diiminopyridine (L2), bis(5-bromosalicylaldehyde)2,6-diiminopyridine (L3), bis(5-nitrosalicylaldehyde)2,6-diiminopyridine (L4)] complexes were synthesized and characterized by IR, UV?Cvis and elemental analysis. Methanol solvent is coordinated to uranyl complexes. The electrochemical properties of the uranyl complexes were investigated by cyclic voltammetry in DMF solvent. Thermogravimetry and differential thermoanalysis of the uranyl complexes were carried out in the range of 20?C700?°C. The UO2L4 complex was decomposed in two and the others were decomposed in three stages. Up to 85?°C, the coordinated solvent was released then the Schiff base ligands were decomposed in one or two steps. Decomposition of synthesized complexes is related to the Schiff base characteristics. The thermal decomposition reaction is first order for the studied complexes. 相似文献
969.
J Matos LK Ono F Behafarid JR Croy S Mostafa AT DeLaRiva AK Datye AI Frenkel B Roldan Cuenya 《Physical chemistry chemical physics : PCCP》2012,14(32):11457-11467
The thermal stability of inverse micelle prepared Pt nanoparticles (NPs) supported on nanocrystalline γ-Al(2)O(3) was monitored in situ under different chemical environments (H(2), O(2), H(2)O) via extended X-ray absorption fine-structure spectroscopy (EXAFS) and ex situ via scanning transmission electron microscopy (STEM). Drastic differences in the stability of identically synthesized NP samples were observed upon exposure to two different pre-treatments. In particular, exposure to O(2) at 400 °C before high temperature annealing in H(2) (800 °C) was found to result in the stabilization of the inverse micelle prepared Pt NPs, reaching a maximum overall size after moderate coarsening of ~1 nm. Interestingly, when an analogous sample was pre-treated in H(2) at ~400 °C, a final size of ~5 nm was reached at 800 °C. The beneficial role of oxygen in the stabilization of small Pt NPs was also observed in situ during annealing treatments in O(2) at 450 °C for several hours. In particular, while NPs of 0.5 ± 0.1 nm initial average size did not display any significant sintering (0.6 ± 0.2 nm final size), an analogous thermal treatment in hydrogen leads to NP coarsening (1.2 ± 0.3 nm). The same sample pre-dosed and annealed in an atmosphere containing water only displayed moderate sintering (0.8 ± 0.3 nm). Our data suggest that PtO(x) species, possibly modifying the NP/support interface, play a role in the stabilization of small Pt NPs. Our study reveals the enhanced thermal stability of inverse micelle prepared Pt NPs and the importance of the sample pre-treatment and annealing environment in the minimization of undesired sintering processes affecting the catalytic performance of nanosized particles. 相似文献
970.
Mohsen Rostamizadeh Malek Taher Maghsoodlou Sayyed Mostafa Habibi‐Khorassani Nourallah Hazeri Faramarz Rostami Charati Mohammad Amin Kazemian Brian W. Skelton Mohamed Makha 《Heteroatom Chemistry》2011,22(6):715-722
The reaction between dialkyl acetylenedicarboxylates and NH heterocyclic compounds in the presence of triethyl phosphite leads to stable phosphorus ylide derivatives in good yields. The X‐ray crystallographic data and theoretical study show that there is a resonance between two bonds of C19P1 and C191O191 in phosphorus ylide 4d . This compound crystallizes in the orthorhombic system, space group (Pca21), with unit cell parameters a = 17.3699(3) Å, b = 13.5500(2) Å, c = 18.4627(3) Å, α = 90°, β = 90°, γ = 90°, Z = 8, and V = 4345.4(12) Å3. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:715–722, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20739 相似文献