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91.
Mohammad Ali Amrollahi Zohreh Kheilkordi 《Journal of the Iranian Chemical Society》2016,13(5):925-929
A convenient and direct approach has been developed for the preparation of bis(indole) derivatives by one-pot four-component condensing of indole, aldehydes and active methylene compounds in the presence of 12-tungstophosphoric acid in aqueous media under silent and ultrasound methods. The remarkable advantages are the simplicity of the experimental procedures, short reaction times and high yields with the green aspects by avoiding toxic catalysts and solvents. 相似文献
92.
Alizadeh Kaklar Zahra Ansari Mohammad Reza 《Journal of Thermal Analysis and Calorimetry》2019,135(3):1881-1890
Journal of Thermal Analysis and Calorimetry - Two-phase flow was simulated within the effervescent atomizer by the volume of fluid interface tracing model. Different gas-to-liquid mass ratios... 相似文献
93.
Mohammad Reza Kashefi Alasl Mahmoud Reza Sohrabi Mehran Davallo 《Journal of separation science》2019,42(9):1777-1785
In this work, a fast and simple magnetic dispersive solid phase extraction methodology was developed utilizing Ag@magnetite nanoparticles@graphene nanocomposite as an efficient magnetic nanosorbent for preconcentration and determine of five aromatic amines in water samples. The sorbent was characterized by diverse characterization techniques. After the extraction, high‐performance liquid chromatography with UV detection was utilized to analysis the aromatic amines. The effects of different factors on the extraction process were studied thoroughly via design of experiment and desirability function. Detection limits and linear dynamic ranges were obtained in the range of 0.10–0.20 and 0.3–300 μg/L, respectively. The relative standard deviations (n = 5) were in the range of 4.3–6.5%. Eventually, the method was employed for determination of target aromatic amines in various water samples. 相似文献
94.
Shadpour Mallakpour Mohammad Dinari 《Journal of Thermal Analysis and Calorimetry》2013,114(1):329-337
Considering the importance of the nanocomposites, the present work focuses on some new hybrid materials prepared by introducing reactive organoclay (OC) into the chiral poly(amide-imide) (PAI) matrix. At first, Cloisite Na+ was modified with protonated l-isoleucine amino acid. Then, PAI containing phenylalanine was synthesized via solution polycondensation of chiral diacid chloride with 4,4′-diaminodiphenylsulfone and was characterized with Fourier transform infrared (FTIR) and 1H NMR techniques. At last, PAI/OC nanocomposite films containing 2, 5, 10, and 15 % of OC were prepared via solution intercalation method. The effect of OC dispersion and the interaction between OC and polymer chains on the properties of nanocomposites were investigated using FTIR, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, tensile testing of thin films, and thermogravimetry analysis techniques. The thermal stability of hybrids such as the decomposition temperature and mass residue at 800 °C was improved. Mechanical data indicated improvement in the tensile strength of the nanocomposites with OC loading up to 10 wt%. The transparency of the hybrid films was investigated by means of UV–Vis spectra. 相似文献
95.
Mohammad Hossein Habibi Amir Hossein Habibi 《Journal of Thermal Analysis and Calorimetry》2013,113(2):843-847
Zinc ferrite nanocomposite was synthesized via thermal decomposition of zinc acetate and iron nitrate at three different temperatures (350, 450, and 550 °C). The influence of the thermal decomposition of precursors on the formation zinc ferrites was studied by differential thermal gravimetry and thermogravimetry (TG). The TG curve shows two steps for the thermal decomposition with mass loss of 17.3 % at 78 °C and 63.3 % at 315 °C. The prepared zinc ferrites nanocomposite was characterized by X-ray diffraction and scanning electron microscopy. The X-ray diffractograms of ZnFe2O4 shows that a crystalline phase, spinel system is formed. SEM micrograph of the zinc ferrite nanocomposite indicates the formation of uniformly spherical 48-nm nanograins. The properties of the zinc ferrite phase were strongly dependent on their calcinations temperature and molar ratio of precursors. 相似文献
96.
Mohammad Yazdanbakhsh Nahid Lotfian Haman Tavakkoli Roland Boese 《Central European Journal of Chemistry》2011,9(4):585-589
A novel oxo-centered trinuclear mixed-metal carboxylate complex with unsaturated bridging ligands [Fe2Cr(μ3-O)(C3H3O2)6(H2O)3]·NO3·4H2O has been synthesized and characterized by means of Elemental analyses, Infrared spectroscopy and Crystal structure analysis.
The compound crystallizes isotypically in the monoclinic space group type P21/c. In the compound, each M(III) cation is coordinated by six O atoms from four unsaturated carboxylate groups as bridging ligands, one water molecule as
the terminal ligand, and a μ3-oxygen atom in the center of an equilateral triangle. The infrared spectra show resolved bands arising from νasym(COO) and νsym(COO) vibration of bridging carboxylate ligands along with those of νasym(M2M′O) vibration in the complex. The difference between symmetrical and asymmetrical (COO) ligands indicate that the acrylate
bridge is present in the structure of complex.
相似文献
97.
Phosphorus pentoxide supported on silica gel (P2O5/SiO2) has been used as an efficient and reusable catalyst for the one‐pot pseudo four‐component synthesis of 2,4,5‐trisubstituted imidazoles from benzil or benzoin, aldehydes, and ammonium acetate. It was also used for four‐component preparation of 1,2,4,5‐tetrasubstituted imidazoles from benzil or benzoin, aldehydes, primary amine, and ammonium acetate under thermal solvent‐free conditions. The remarkable features of this new procedure are high conversions, cleaner reaction, simple experimental and work‐up procedures and also the catalyst can be easily separated from the reaction mixture and reused several times without any loss of its activity. 相似文献
98.
Mohammad Ghadermazi Marilyn M. Olmstead Jafar Attar Gharamaleki Shahideh Rostami 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(4):o134-o138
Two related proton‐transfer compounds, namely piperazine‐1,4‐diium 4‐oxo‐4H‐pyran‐2,6‐dicarboxylate monohydrate, C4H12N22+·C7H2O62−·H2O or (pipzH2)(cdo)·H2O, (I), and piperazine‐1,4‐diium bis(6‐carboxy‐4‐oxo‐4H‐pyran‐2‐carboxylate), C4H12N22+·2C7H3O6− or (pipzH2)(cdoH)2, (II), were obtained by the reaction of 4‐oxo‐4H‐pyran‐2,6‐dicarboxylic acid (chelidonic acid, cdoH2) and piperazine (pipz). In (I), both carboxyl H atoms of chelidonic acid have been transferred to piperazine to form the piperazine‐1,4‐diium ion. The structure is a monohydrate. All potential N—H donors are involved in N—H...O hydrogen bonds. The water molecule spans two anions via the 4‐oxo group of the pyranose ring and a carboxylate O atom. The hydrogen‐bonding motif is essentially two‐dimensional. The structure is a pseudomerohedral twin. In the asymmetric unit of (II), the anion consists of monodeprotonated chelidonic acid, while the piperazine‐1,4‐diium cation is located on an inversion centre. The single carboxyl H atom is disordered in two respects. Firstly, the disordered H atom is shared equally by both carboxylic acid groups. Secondly, the H atom is statistically disordered between two positions on either side of a centre of symmetry and is engaged in a very short hydrogen‐bonding interaction; the relevant O...O distances are 2.4549 (11) and 2.4395 (11) Å, and the O—H...O angles are 177 (6) and 177 (5)°, respectively. Further hydrogen bonding of the type N—H...O places the (pipzH2)2+ cations in pockets formed by the chains of (cdoH)− anions. In contrast with (I), the (pipzH2)2+ cations form hydrogen‐bonding arrays that are perpendicular to the anions, yielding a three‐dimensional hydrogen‐bonding motif. The structures of both (I) and (II) also feature π–π stacking interactions between aromatic rings. 相似文献
99.
We studied the chemical wave activity of the pyrocatechol‐acidic bromate system in the presence of ferroin‐loaded beads. The wave activity lasted for more than 24 h while meandering spirals continued for up to 10 h. Rigid and meandering spiral waves were investigated. We have analyzed the wave propagation speed and spiral tip trajectory versus the initial concentrations of all reagents as well as the age of the solution. Wave velocity depends on [H+] and [BrO] concentrations by the relationship v=k[H+]1/2[BrO]1/2, which is in agreement with other studies. This system is ideal to study wave activity and spiral waves as it does not produce precipitates under the studied conditions. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 198–203, 2011 相似文献
100.
Gholamreza Vaghar-Lahijani Mohammad Saber-Tehrani Parviz Aberoomand-Azar Mojtaba Soleimani 《Journal of Analytical Chemistry》2018,73(2):145-151
In this study, an effective method of ultrasound-assisted ionic liquid based dispersive liquid–liquid microextraction (UA?IL?DLLME) coupled with HPLC was applied for extraction and determination of two antidepressant drugs: venlafaxine hydrochloride and amitriptyline hydrochloride from human plasma samples. Three ionic liquids were studied: 1-butyl-3-methyl imidazolium hexafluorophosphate, 1-hexyl-3- methyl imidazolium hexa-fluoro-phosphate, and 1-octyl-3-methyl imidazolium hexafluorophosphate [C8MIM][PF6]. Various factors affect the stages and efficiency of extraction, some of which are pH of sample solution, type and volume of ionic liquid, the time of ultrasonication, centrifuging time and rate, and the ionic strength of solution. In this research, optimum conditions were obtained as 55 μL of [C8MIM][PF6] selected as ionic liquid, pH 11, 2% NaCl, 4 min ultrasonication and 5 min centrifuging at 3500 rpm. Under the optimized conditions, the linearity was obtained in the range of 0.2 to 250 μg/L. The limits of detection were 0.5 μg/L for venlafaxine and 0.8 μg/L for amitriptyline. Pre-concentration factors were 1.3 × 103 for venlafaxine and 1.2 × 103 for amitriptyline. The UA?IL?DLLME method coupled with HPLC was successfully used for the determination of venlafaxine and amitriptyline spiked into the real samples of human plasma. 相似文献