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81.
Bita SoleymanifardMajid M. Heravi Morteza Shiri Mohammad Ali ZolfigolMohammad Rafiee Hendrik G. KrugerTricia Naicker Farzaneh Rasekhmanesh 《Tetrahedron letters》2012,53(28):3546-3549
Arylidenepyruvic acids (APAs) have been successfully employed in an Ugi-four component condensation reaction which yielded polyfunctional amides. Condensation of various APAs, aldehydes, amines, and isocyanides at room temperature in 96% ethanol as a green solvent proceeded in good yields. The extension of the reaction to diamines, formaldehyde, and isocyanides to form more complex molecules is also reported. These novel products may have potential in various pharmaceutical applications. 相似文献
82.
Khalafi L Rafiee M Sedaghat S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):661-665
The kinetic of the nitrous acid reactions with quercetin and catechin has been studied using spectrophotometric method in aqueous solution. The results show that these antioxidants participate in oxidation reactions with nitrous acid which is derived from protonation of nitrite ion in mild acidic conditions. Corresponding o-quinones as relatively stable products were detected by spectrophotometric techniques. pH dependence of the reactions has been examined and the rate constants of reactions were obtained by non-linear fitting of kinetic profiles. The effect of β-cyclodextrin on the oxidation pathway was another object of this study. It is shown that β-cyclodextrin has an inhibitory effect on the oxidation reaction. The rate constants of oxidation reactions for complexed forms and their stability constants were obtained based on changes in the reaction rates as a function of β-cyclodextrin concentration. 相似文献
83.
Amin Zarei Leila Khazdooz Abdol R. Hajipour Fatemeh Rafiee Ghobad Azizi Fatemeh Abrishami 《Tetrahedron letters》2012,53(4):406-408
An efficient and straightforward procedure for the Suzuki–Miyaura cross-coupling reaction was studied by using aryldiazonium silica sulfates and sodium tetraphenylborate in the presence of a catalytic amount of Pd(OAc)2. These reactions were carried out in water at room temperature without using additional ligands. 相似文献
84.
Masoud Nasr-Esfahani Zahra Rafiee Hassan Kashi 《Journal of the Iranian Chemical Society》2016,13(8):1449-1461
Tungstophosphoric acid nanoparticles supported on polyamic acid (TPA NPs/PAA) was prepared and employed as a catalyst for the facile selective synthesis of 1,8-dioxo-decahydroacridines and some bulky bis(1,8-dioxo-decahydroacridine)s via one-pot condensation of 5,5-dimethyl-1,3-cyclohexanedione and various aldehydes with aniline or ammonium acetate in ethanol–water solution. This catalyst was characterized by FT-IR, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), energy-dispersive X-ray analysis (EDAX), and inductively coupled plasma optical emission spectrometry (ICP-OES). The catalyst showed high thermal stability and good reusability. The products were isolated in high purity and the catalyst was easily separated in a simple workup and recycled several times without noticeable loss of activity under the described reaction conditions. The reaction is characterized by short reaction time, high efficiency, and mild reaction conditions. 相似文献
85.
In this study, the synthesis of sulfonic acid supported on ferrite–silica superparamagnetic nanoparticles (Fe3O4@SiO2@SO3H) as a nanocatalyst with large density of acidic groups is suggested. This nanocatalyst was prepared in three steps: preparation of colloidal iron oxide magnetic nanoparticles (Fe3O4 MNPs), coating of silica on Fe3O4 MNPs (Fe3O4@SiO2) and incorporation of sulfonic acid as a functional group on the surface of Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2@SO3H). The properties of the prepared magnetic nanoparticles were characterized using transmission electron microscopy, infrared spectroscopy, vibrating sample magnetometry, X‐ray diffraction and thermogravimetric analysis. Finally, the applicability of the synthesized magnetic nanoparticles was tested as a heterogeneous solid acid nanocatalyst for one‐pot synthesis of diindolyloxindole derivatives in aqueous medium. Oxindole derivatives were produced by the coupling of indole and isatin compounds with good to high yields (60–98%). Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
86.
The activity of [Pd{C6H4(CH2N(CH2Ph)2)}(μ‐Br)]2 complex was investigated in cross‐coupling reactions of triethoxy(phenyl)silane with various aryl halides under microwave irradiation. This complex is an efficient and stable catalyst for the synthesis of substituted biphenyls that is non‐sensitive to air and moisture. The combination of dimeric complex as homogenous catalyst, microwave irradiation, DMF as microwave‐active polar solvent and TBAF as microwave‐active additive led to excellent yields in short reaction times. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
87.
88.
Lida?KhalafiEmail author Mohammad?Rafiee Farzaneh?Yadaei 《Research on Chemical Intermediates》2011,37(8):1047-1055
The reaction of electrochemically generated o-benzoquinones from oxidation of quercetin and catechin as Michael acceptors with cyanide ion as nucleophile has been studied
using cyclic voltammetry. The reaction mechanism is believed to be EC; including oxidation of catechol moiety of these antioxidants
followed by Michael addition of cyanide ion. The observed homogeneous rate constants (k
obs) for reactions were estimated by comparing the experimental voltammetric responses with the digitally simulated results based
on the proposed mechanism. The effects of pH and nucleophile concentration on voltammetric behavior and the rate constants
of chemical reactions were also described. 相似文献
89.
Mohammad A. Rafiee Fazel Yavari Javad Rafiee Nikhil Koratkar 《Journal of nanoparticle research》2011,13(2):733-737
In this study, we characterized the mechanical properties of fullerence (C60) epoxy nanocomposites at various weight fractions of fullerene additives in the epoxy matrix. The mechanical properties measured
were the Young’s modulus, ultimate tensile strength, fracture toughness, fracture energy, and the material’s resistance to
fatigue crack propagation. All of the above properties of the epoxy polymer were significantly enhanced by the fullerene additives
at relatively low nanofiller loading fractions (~0.1 to 1% of the epoxy matrix weight). By contrast, other forms of nanoparticle
fillers such as silica, alumina, and titania nanoparticles require up to an order of magnitude higher weight fraction to achieve
comparable enhancement in properties. 相似文献
90.
A highly porous silica-supported tungstophosphoric acid (PW) nanocluster was prepared for use in solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs). The PWs represent a class of discrete transition metal-oxide nanoclusters and their structures resemble discrete fragments of metal-oxide structures of definite size and shape. Transition metal-oxide nanoclusters display large structural diversity, and their monodisperse sizes can be tuned from several Ångstroms up to 10 nm. The highly porous silica-supported tungstophosphoric acid nanocluster material is found to be capable of efficiently extracting PAHs from aqueous sample solutions. The nanomaterial was immobilized on a stainless steel wire for fabrication of the SPME fiber. Following thermal desorption, the PAHs were quantified by GC-MS. Analytical merits include limits of detection that range from 0.02 to 0.1 pg mL?1 and a dynamic range as wide as from 0.001 to 100 ng mL?1. Under optimum conditions, the repeatability for one fiber (n?=?3), expressed as the relative standard deviation, is between 4.3 % and 8.6 %. The method is simple, rapid, and inexpensive. The thermal stability of the fiber and the high relative recovery make this method superior to conventional methods of extraction.
The highly porous silica-supported tungstophosphoric acid nanocluster material is found to be capable of efficiently extracting PAHs from aqueous sample solutions. The prepared nanomaterial was immobilized onto a stainless steel wire for fabrication of the SPME fiber. Following thermal desorption, the PAHs were quantified by GC-MS. 相似文献