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Kermānshāh, Iran

Rafiee E.,Razi University | Rafiee E.,Kermanshah Oil Refining Company | Shahebrahimi S.,Razi University
Cuihua Xuebao/Chinese Journal of Catalysis | Year: 2012

Nano silica was prepared from rice husk with high surface area. X-ray diffraction (XRD) pattern showed that the amorphous form of silica was produced. Chemical composition of the nano silica was estimated by X-ray fluorescence spectroscopy and CHN analysis. The nano silica was used as a support for H 3PW 12O 40. The nano silica and nano silica supported H 3PW 12O 40 were characterized by inductively coupled plasma, XRD, transmission electron microscopy (TEM), N 2 adsorption-desorption, and Fourier transform infrared spectroscopy. TEM images of nano silica as well as the supported catalyst displayed average size of 6 and 7 nm, respectively. The catalyst showed excellent activity in some important organic reactions including Biginelli, Hantzsch, Mannich, and Claisen-Schmidt reactions with good reusability. Catalytic activity of this nano catalyst is an improvement over the commercially available silica that is used to support H 3PW 12O 40. Source

Rafiee E.,Razi University | Rafiee E.,Kermanshah Oil Refining Company | Eavani S.,Razi University
Green Chemistry | Year: 2011

A new type of magnetically-recoverable catalyst was synthesized by the immobilization of H 3PW 12O 40 on the surface of silica-encapsulated γ-Fe 2O 3 nanoparticles. This catalyst was characterized by transmission electron microscopy (TEM), a laser particle size analyzer, infrared spectroscopy (IR) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The results show that the particles are mostly spherical in shape and have an average size of approximately 94 nm. The characterization data derived from IR spectroscopy reveal that H 3PW 12O 40 on the support exists in the Keggin structure. The acidity of the catalyst was measured by a potentiometric titration with n-butylamine. To our surprise, this very strong solid acid catalyst showed an excellent distribution of acid sites, suggesting that the catalyst possesses a higher number of surface active sites compared to its homogeneous analogues. The activity of the catalyst was probed through one-pot three-component Mannich-type reactions of aldehydes, amines and ketones in water at room temperature. The excellent conversions show that the catalyst has strong and sufficient acidic sites, which are responsible for its catalytic performance. After the reaction, the catalyst/product separation could be easily achieved with an external magnetic field, and more than 95% of the catalyst could usually be recovered. The catalyst was reused at least five times without any loss of its high catalytic activity. © 2011 The Royal Society of Chemistry. Source

Gholivand M.-B.,Razi University | Jalalvand A.R.,Razi University | Jalalvand A.R.,Kermanshah Oil Refining Company | Goicoechea H.C.,National University of Santa | Omidi M.,Razi University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013

For the first time, interaction of nuclear fast red (NFR) with human serum albumin (HSA) was studied by experimental and computational approaches. Firstly, experimental measurements including fluorescence spectroscopy (F), UVvis spectrophotometry (UVvis), cyclic voltammetry (CV), differential pulse voltam-metry (DPV) and linear sweep voltammetry (LSV) were separately used to investigate the interaction of NFR with HSA and interesting thermodynamics information was obtained from these studies. Secondly, new information including electrochemical behavior of NFR-HSA complex species, relative concentrations of the various reacting species and effects of NFR on the sub-structure of HSA was obtained by applying multivariate curve resolution-alternating least squares (MCR-ALS). In this case, a row- and column-wise augmented matrix was built with DPV, LSV, F and UVvis sub-matrices and resolved by MCR-ALS. Surprisingly, by this method two NFR-HSA complex species with different stoichiometries and different electrochemical behaviors were found. Furthermore, by the use of the recorded voltammetric and spectroscopic data the binding constants of complex species were computed by EQUI-SPEC (a hard-modeling algorithm). Finally, the binding of NFR to HSA was modeled by molecular modeling and molecular dynamics (MD) simulations methods. Excellent agreement was found between experimental and computational results. Both experimental and computational results suggested that the NFR binds mainly to the sub-domain IIA of HSA. © 2013 Elsevier B.V. All rights reserved. Source

Rafiee E.,Razi University | Rafiee E.,Kermanshah Oil Refining Company | Eavani S.,Razi University | Nejad F.K.,Razi University | And 2 more authors.
Tetrahedron | Year: 2010

A series of insoluble salts of Keggin heteropoly compounds were prepared and used as catalysts for the Mannich-type reaction of benzaldehyde, aniline, and cyclohexanone in water. Among them, Cs2.5H0.5PW 12O40 showed excellent catalytic activity. Effects of surfactant, catalyst loading and temperature were studied to introduce the best reaction condition. The optimized reaction conditions were extended to Mannich reaction of various aldehydes, ketones, and amines in water. This rapid procedure afforded structurally divers β-amino ketones with major anti diastereoselectivity. Additionally, four new compounds were reported. The catalyst was recovered and reused for subsequent runs. © 2010 Elsevier Ltd. All rights reserved. Source

Rafiee E.,Razi University | Rafiee E.,Kermanshah Oil Refining Company | Khodayari M.,Razi University | Shahebrahimi S.,Razi University | And 2 more authors.
Journal of Molecular Catalysis A: Chemical | Year: 2011

Nano silica has been prepared from rice husk, which is an agricultural waste, with high surface area and in amorphous form. 12-Tungstophosphoric acid, H3PW12O40 (PW) has been supported on this silica to produce nano silica supported PW (NPW/SiO2) as a nano catalyst. Characterization of this catalyst has been investigated by TEM, FTIR, and ICP, also, acidic properties have been studied by potentiometric titration method. 40% NPW/SiO2 has been used as a high effective catalyst for benzylation of 1,3-dicarbonyl compounds with benzylic alcohols. The present methodology offers a clean, practical, simple, mild, environmentally friendly, green and time-saving method under solvent free condition. Also, the catalyst is a good candidate for large-scale in direct benzylation of 1,3-dicarbonyl compounds. © 2011 Elsevier B.V. All rights reserved. Source

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