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101.
Silica‐supported tin chloride [SiO2‐Sn(Cl)4‐n] has been prepared by mixing tin chloride with activated silica gel in toluene under refluxing conditions for one day. A range of primary, secondary, and tertiary alcohols as well as phenolic hydroxyl groups were converted into their corresponding trimethylsilyl ethers with hexamethyldisilazane in the presence of catalytic amounts of silica‐supported tin chloride at room temperature. An excellent chemoselective silylation of hydroxyl groups in the presence of other functional groups was also observed. This catalyst could be recycled and reused fifteen times without loss of efficiency. 相似文献
102.
Tunable N‐doped carbon nanospheres from sucrose as carbon source and Tris(2‐aminoethyl)amine (TAEA) as nitrogen source by a simple and easily reproducible method were prepared. It was demonstrated that the tunable N‐doping of carbon spheres could be realized by altering the ratio of TAEA in the raw materials. The content of doped nitrogen, surface area, pore volume and pore size of carbon nanospheres were increased with the increasing of TAEA amount in the hydrothermal process. Prepared N‐doped carbon nanospheres act as solid ligand for anchoring of Ag NPs which generated via chemical reduction of Ag ions. Benzylic alcohols and aldehydes were converted into the aryl nitriles by using Ag/N‐CS‐1 nanospheres as the catalyst and O2 as the oxidant, efficiently. This catalyst was stable and could use for 6 successful runs. 相似文献
103.
Kamyabi Mohammad Ali Hashemi Heris Mir Karim Jadali Salma 《Journal of Solid State Electrochemistry》2021,25(4):1283-1292
Journal of Solid State Electrochemistry - In this work, a polymer composite based on poly 4-aminothiophenol (p-ATP) is prepared via a facile electrochemical route and is used as an appropriate... 相似文献
104.
Nashmil Karimian Pegah Hashemi Abbas Afkhami Hasan Bagheri 《Current Opinion in Electrochemistry》2019
The present study reports the wireless technique that generates asymmetric reactivity on the surface of the conducting substrate without any direct electrical connection in the electrolyte solution by inducing external power. In recent years, bipolar electrochemical systems have received special attention that they are used for new kinds of electrochemical applications ranging from electrodeposition to electroanalytical chemistry. Bipolar electrochemistry is a unique technique because of the lack of direct electrical connection to the bipolar electrode. In this perspective article, we first illustrate the concept and history of the bipolar electrochemistry as well as their application based on the open and closed bipolar configuration in different fields. 相似文献
105.
This paper focuses on the magnetic, structural and thermal properties of mechanically alloyed Y2O3/α-Fe2O3 mixed powders and investigates the effects of the mechanical milling and heat treatment on the synthesis of yttrium iron garnet from the primary materials. The morphological and structural studies were carried out by scanning electron microscope and X-ray diffraction, respectively. The thermal activities were measured by differential thermal analysis. The magnetic properties were studied by vibrating sample magnetometer. The results showed that high-energy milling does not lead to the garnet formation and even does not decrease the temperature of the garnet formation. Furthermore, the orthoferrite phase can be achieved slightly during the milling process (up to 96 h) and completely by the heat treatment at lower temperatures (850 °C). 相似文献
106.
Seyed Hossein Hashemi 《印度化学会志》2022,99(6):100508
The first fundamental step in determining the physicochemical properties of an equilibrium system is to determine the activity coefficient of electrolyte and non-electrolyte ions. Based on understanding the importance of activity coefficient in thermodynamic systems in this study, in order to predict interfacial tension between oil and aqueous phases composed of ionic liquids and brine, a modified thermodynamic equation based on concentration and coefficient of activity of ionic liquids is defined. For this study, the Extended UNIQUAC model is desired and its adjustable parameters are optimized with Genetic + PSO algorithm. The modified model has practical features such as investigating the effect of concentrations of salts in the water of oil fields formation on the interfacial tension of the system, investigating the effect of concentrations of various organic compounds such as ionic liquids on the interfacial tension of the system and investigating the interaction energy between organic and inorganic ions. In this study, the optimization of the modified thermodynamic equation to predict the interfacial tension of solutions containing [C8Py][Cl], [C18Py][Cl], [C12mim][Cl] and [C18mim][Cl] with the presence of brine and distilled water is investigated. Also, the effect of ionic strength of the solution in 32 equilibrium systems on interfacial tension is investigated. According to the optimization results of this study, the design of a computer program can be considered to predict the interfacial tension with the presence of ionic liquids and salts. 相似文献
107.
108.
Tahereh Khajvand Olia Alijanpour Mohammad Javad Chaichi Majid Vafaeezadeh Mohammad Mahmoodi Hashemi 《Analytical and bioanalytical chemistry》2015,407(20):6127-6136
The effects of six synthetic imidazolium-based ionic liquids (ILs) on the CuII-catalyzed chemiluminescence of lucigenin (Luc-CL) in the pH range 6.0–11 were investigated. Preliminary experiments found that the CL emission was strongly enhanced or inhibited in the presence of the ILs. The degree of enhancement or inhibition of the CL intensity in the presence of each IL was related to the molecular structure of the IL, the medium used, and the pH. The maximum enhancement of the CL intensity was observed at pH 9.0 (amplification factor?=?443). This decrease in the pH at which maximum CL enhancement occurred and the substantial signal amplification of the Luc-CL may be related to a strong interaction between CuII and the imidazolium ring of superior ILs at this pH. Additionally, the formation of IL microdomains in semi-aqueous media permitted more solubility of the product yielded by the Luc-CL reaction (N-methylacridone), which could increase the CL intensity. To obtain consistent data on the catalytic efficiency of CuII in the presence of various ILs as well as the corresponding CL emission intensities, fluorescence quantum yields (Φ F) of lucigenin were measured under the same conditions. Comparison of the data pointed to the mechanism that controls the properties of Luc-CL in the presence of the CuII/IL complexes. Based on the catalytic effect of the CuII/IL complex and the measurement of the enzymatically generated H2O2, a novel, simple, and sensitive CL method for determining glucose with a detection limit (LoD) of 6.5 μM was developed. Moreover, this method was satisfactorily applied to the determination of glucose in human serum and urine samples. 相似文献
109.
Payman Hashemi Sayyed Mohammad Hosseini Ali Kakanejadifard Gholamhassan Azimi Somayeh Zohrehvand 《中国化学会会志》2010,57(1):111-117
A dispersive liquid‐liquid microextraction (DLLME) technique was proposed for the enrichment and graphite furnace atomic absorption spectrometric (GFAAS) determination of Cu2+ in water samples. In this method a mixture of 480 μL acetone (disperser solvent) containing 26 μg S,S‐bis(2‐aminobenzyl)‐dithioglyoxime (BAT) ligand and 20 μL carbon tetrachloride (extraction solvent) was rapidly injected by a syringe into 5 mL aqueous sample containing copper ions (analyte). Thereby, a cloudy solution formed. After centrifugation, the fine droplets containing the extracted copper complex were sedimented at the bottom of the conical test tube. This phase was collected by a microsyring and after dilution by methanol, 20 μL of it was injected into the graphite tube of the instrument for analysis. Effects of some parameters on the extraction, such as extraction and disperser solvent type and volume, extraction time, salt concentration, pH and concentration of the chelating agent were optimized. The response surface method was used for optimization of the effective parameters on the extraction recovery. Under these conditions, an enrichment factor of 312 was obtained. The calibration graph was linear in the rage of 2–50 μ L−1 Cu2+ with a detection limit of 0.03 μg L−1 and a relative standard deviation (RSD) for five replicate measurements of 3.4% at 20 μg L−1 Cu2+. The method was successfully applied to the determination of Cu2+ in some spring water samples. 相似文献
110.
Kamal Alizadeh Somaieh Zohrevand Ali Reza Ghiasvand Payman Hashemi Mojtaba Shamsipur Hashem Sharghi Reza Khalifeh 《Mikrochimica acta》2010,168(1-2):115-121
A fast and reliable method was developed for the selective separation and preconcentration of Cu2+ ions using homogeneous liquid-liquid extraction using a novel benzo-substituted macrocyclic diamide, 5,6,7,8,9,10-hexahydro-2H-1,13,4,7,10-benzodioatriazacyclo-pentadecine-3,11(4 H,12 H)-dione, as a selective complexing agent. An aqueous solution of Zonyl FSA (FSA) was used as a phase-separation agent at pH 4.5. Electrothermal atomic absorption spectrometry was used for Cu2+ determination after preconcentration. The influences of pH, type and volume of the water-miscible organic solvent, concentration of FSA, concentration of the ligand and the effect of diverse ions were investigated. Factorial design and response surface methods were used for the optimization purposes. Under the optimum experimental conditions, 50 ng of Cu2+ in 5 mL aqueous sample could be extracted quantitatively into 76 µL of the sediment phase. The maximum preconcentration factor was 65. The calibration curve was linear in the concentration range 0.2 to 4.0 µg L?1. The detection limit and relative standard deviation were 4 ng L?1 and 4.6%, respectively. The method was successfully applied to the extraction and determination of Cu2+ in natural water samples. 相似文献