γ-Al2O3-Supported 12-Tungstosilicic Acid as an Efficient Heterogeneous Catalyst for the Synthesis of α-Aminonitrile

The multicomponent Strecker reaction using trimethylsilyle cyanide was performed in very short reaction times, and α-aminonitriles were prepared in excellent yields in the presence of a catalytic amount of alumina-supported tungstosilicic acid.     

Numerical investigation of various nanofluid heat transfers in microchannel under the effect of partial magnetic field: lattice Boltzmann approach

Journal of Thermal Analysis and Calorimetry - In the present paper, the effect of the external partial magnetic field is studied on the flow and heat transfer of various nanofluids in a...     

Unmodified Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanostructure promoted with external magnetic field: safe,magnetically recoverable,and efficient nanocatalyst for N- and C-alkylation reactions in green conditions

Transition metal compounds have emerged as suitable catalysts for organic reactions. Magnetic compounds as soft Lewis acids can be used as catalysts for organic reactions. In this report, the Fe₃O₄ nanostructures were obtained from Fe²⁺ and Fe³⁺-salts, under an external magnetic field (EMF) without any protective agent. The X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy tools were used to characterize these magnetic compounds. The two-dimensional (2-D, it showed nanometric size in the two dimensions, nanorod structure) Fe₃O₄ compound showed high catalytic activity and stability in N- and C-alkylation reactions. A diverse range of N- and C-alkylation products were obtained in moderate to high yield under green and mild conditions in air. Also the N- and C-alkylation products can be obtained with different selectivity and yield by exposure reactions with EMF. Results of alkylation reactions showed that the presence of Fe(II) and Fe(III) species on the surface of magnetic catalysts (phase structure of magnetic compounds) are essential as very cheap active sites. Also, morphology of magnetic catalysts had influence on their catalytic performances. After the reaction, the catalyst/product(s) separation could be easily achieved with an external magnet and more than 95% of catalyst could be recovered. The catalyst was reused at least four times without any loss of its high catalytic activity for N- and C-alkylation reactions.     

P NMR study of the stoichiometry, stability and thermodynamics of new complexation between uranyl (II) nitrate and N-methyliminobis(methylenephosphonic acid) in two binary D2O-DMSO-d6 solvent mixtures

The complexation reaction between uranyl (II) nitrate, and N-methyliminobis(methylenephosphonic acid) (MIDPH) was investigated in two different binary solvent mixtures of D₂O-DMSO-d₆ at various temperatures using ³¹P NMR spectroscopy. The exchange between the free ligand and the 1:1 complexed ligand was slow on the NMR timescale and two ³¹P NMR signals were observed. The formation constant of the resulting complex was evaluated from integration of the two ³¹P NMR signals. The values of thermodynamic parameters of the resulting complex (ΔH, ΔS and ΔG) were determined from the temperature dependence of the formation constants. In the two solvent mixtures studied, the resulting complex is enthalpy stabilized but entropy destabilized.     

Cs_xH_(3-x)PW_(12)O_(40) heteropoly salts catalyzed quinoline synthesis via Friedl(a|¨)nder reaction

Various type of cesium partially substituted phosphotungstate,Cs_xH_3-xPW₁₂O₄₀（x = 1.0,2.0 and 2.5）,were synthesized and their catalytic activities were investigated in the synthesis of quinoline.It was shown that catalytic activities of these catalysts correlated to surface acidity and total number of acidic sites.Finally,a series of quinoline derivatives were synthesized with Cs_2.5H_0.5PW₁₂O₄₀ via the Friedlander reaction in high to excellent yields and the plausible mechanism was proposed.Simple experiment,catalyst reusability,short reaction time and preclusion of toxic solvent are the advantages of this method.     

A new insight on hydrogen bond donor property of bridged B–H–B protons in the interaction of diborane with some hydrogen bond acceptor molecules

Structural Chemistry - Ab initio calculations at the MP2/6-311++G(d,p) computational level were used to analyze the interactions between a molecule of B2H6 with some small molecules which often...