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41.
42.
Törnkvist A Nilsson S Amirkhani A Nyholm LM Nyholm L 《Journal of mass spectrometry : JMS》2004,39(2):216-222
The electrospray ionization (ESI) voltage is shown to interfere with liquid chromatographic separations performed with packed porous graphitic carbon (PGC) capillary columns. This interference is ascribed to the presence of an electric field over the conductive column in the absence of an earth point between the column and the ESI emitter. The current evolved alters the chromatographic behavior of the catecholamine metabolite 3-O-methyl-DOPA significantly, as both peak splitting and a dramatic decrease in the retention time were observed. Furthermore, the response from the mass spectrometer was decreased by 33% at the same time. A related compound, tyrosine, exhibited decreased retention times but no peak splitting, whereas no shifts in the retention times (or peak splitting) were seen for the less retained dopamine and noradrenaline. When the current through the PGC column was eliminated by the use of an earth point between the column and the ESI emitter, the chromatographic behavior of the column was found to return slowly to normal after hours of equilibration with 60 : 40 (v/v) methanol-ammonium formate buffer of pH 2.9. The behavior of the PGC column with and without the earth point was found to be highly reproducible during a period of 1 month. We propose that the effect of the ESI voltage on the chromatographic behavior of the PGC column is due to associated redox reactions affecting both the PGC particles and the analytes. It is concluded that (for analytical reasons), care should be taken to ensure that no current is flowing through the chromatographic system when interfacing PGC columns, and conducting parts in general, to ESI mass spectrometry. 相似文献
43.
Ramin Ghorbani-Vaghei Ardeshir Khazaei 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1169-1173
N-Bromobis(p-toluenesulfonyl)amine (NBBTA) is a novel and efficient reagent for the conversion of oximes to their corresponding carbonyl compounds in good yields under mild conditions. 相似文献
44.
Morteza Shiri Mohammad Ali Zolfigol Ardeshir Khazaei Toktam Faal-Rastegar Hendrik G. Kruger 《Journal of the Iranian Chemical Society》2014,11(1):85-90
Multicomponent condensation of ethyl 3-formylindole 2-carboxylate, amines, isocyanide and (S)-N-boc-alanine or (S)-N-boc-serine is described. This Ugi four-component condensation (Ugi-4CC) reaction yielded a series of novel dipeptides containing an indolyl moiety. These compounds exhibit potential biological activity. 相似文献
45.
新型磺酸功能化吡啶盐酸盐离子液体催化剂用于六氢喹啉合成(英文) 总被引:1,自引:0,他引:1
Ardeshir Khazaei Mohammad Ali Zolfigol Ahmad Reza Moosavi-Zare Javad Afsar Abdolkarim Zare Vahid Khakyzadeh Mohammad Hassan Beyzavi 《催化学报》2013,34(10):1936-1944
Sulfonic acid functionalized pyridinium chloride [pyridine-SO3 H]Cl has been synthesized as a novel Brnsted acidic ionic liquid and characterized on the basis of its FT-IR,1H and 13C NMR,MS,ther-mogravimetry,and derivative thermogravimetry data.The material has also been used as a highly efficient,homogeneous,and reusable catalyst for the preparation of hexahydroquinolines according to the one-pot multi-component condensation of arylaldehydes,dimedone(5,5-dimethylcyclohexane-1,3-dione),β-ketoesters,and ammonium acetate under solvent-free conditions. 相似文献
46.
Ardeshir Khazaei Ebrahim Mehdipour Soleiman Yadegari 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):437-441
POLY [N-(4-PYRIDINIUM DICHROMATE)-P-STYRENE SULPHONAMIDE] is readily prepared. It is a stable, mild, and efficient oxidizing reagent that can be used for oxidation of different alcohols to their corresponding carbonyl compounds in approtic solvents. This polymer can be synthesized from the reaction between poly [N-(4-pyridyl)-p-styrene sulphonamide] and CrO 3 in a minimum amount of water. The latter polymer was prepared by free radical polymerization of [N-(4-pyridyl)-p-styrene sulphonamide] by using azobis(isobutyronitrile) (AIBN) as an initiator. N-(4-pyridyl)-p-styrene sulphonamide was synthesized from commercial 4-vinyl benzene sulphonic acid sodium salt and 4-amino pyridine. POLY [N-(4-PYRIDINIUM DICHROMATE)-P-STYRENE SULPHONAMIDE] can oxidize both aliphatic and aromatic alcohols in good yields at a temperature of 38°C and in CH 2 Cl 2 as solvent. One advantage in using this reagent is the mild condition of the reaction system. The synthesized compounds including polymeric reagent and carbonyl compounds were identified by HNMR and IR spectroscopy. 相似文献
47.
Oximes are converted to the parent carbonyl compounds in good yields when treated with 1,3‐dichloro‐5,5‐dimethylhydantoin (DCDMH) ( 1 ). An optimized procedure has been developed; the simple work‐up minimizes loss of product and oximes have been selectively oxidized in the presence of alcohols and alkenes. 相似文献
48.
Nano‐TiO2 as an Efficient Catalyst for Tandem Knoevenagel–Michael‐Cyclocondensation Reaction of Dimedone with Aromatic Aldehydes and Ammonium Acetate or Aromatic Amines under Solvent‐free Conditions
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Ardeshir Khazaei Ahmad Reza Moosavi‐Zare Zahra Mohammadi Vahid Khakyzadeh Javad Afsar 《中国化学会会志》2016,63(2):165-170
TiO2 nanoparticles in anatase and rutile forms was characterized and studied by several techniques including X‐ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and successfully applied as an efficient and heterogeneous catalyst in the synthesis of 1,8‐dioxo‐decahydroacridines via the one‐pot multi‐component condensation reaction of dimedone with aromatic aldehydes and ammonium acetate or aromatic amines under mild and solvent‐free conditions. 相似文献
49.
Condensation of Aryl Aldehydes, 2‐naphthol,and Thioacetamide Catalyzed by N‐halo Reagents in Neutral Media
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Ardeshir Khazaei Fatemeh Abbasi Ahmad Reza Moosavi‐Zare Marzieh Khazaei M. Hassan Beyzavi 《中国化学会会志》2015,62(10):850-854
A new three‐component, highly efficient and solvent‐free approach for the synthesis of known and new 1‐thioamido‐alkyl‐2‐naphthol derivatives was investigated. This was achieved via a one‐pot condensation by reacting aryl aldehydes, 2‐naphthol, and thioacetamide in the presence of catalytic amount of 1,3,5‐trichloro‐1,3,5‐triazinane‐2,4,6‐trione (TCCA) and 1,3‐dichloro‐5,5‐dimethylhydantoin (DCDMH). Mechanistically, the in situ generation of Cl+ ion from TCCA and DCDMH is proposed to catalyse the reactions in neutral media. In the presented work, most of the products have been reported for the first time. 相似文献
50.
Reza Rashidi Meybodi Ardeshir Karami Mohammadi Firooz Bakhtiari-Nejad 《Communications in Nonlinear Science & Numerical Simulation》2012,17(1):454-471
This paper presents the effect of rotor mass on the nonlinear dynamic behavior of a rigid rotor-bearing system excited by mass unbalance. Aerodynamic four-lobe journal bearing is used to support a rigid rotor. A finite element method is employed to solve the Reynolds equation in static and dynamical states and the dynamical equations are solved using Runge-Kutta method. To analyze the behavior of the rotor center in the horizontal and vertical directions under different operating conditions, the dynamic trajectory, the power spectra, the Poincare maps and the bifurcation diagrams are used. From this study, results show how the complex dynamic behavior of this type of system comprising periodic, KT-periodic and quasi-periodic responses of the rotor center varies with changes in rotor mass values by considering two bearing aspect ratios. Results of this study contribute a better understanding of the nonlinear dynamics of an aerodynamic four-lobe journal bearing system. 相似文献