Decoration of β-CD-ZrO on Fe3O4 magnetic nanoparticles as a magnetically,recoverable and reusable catalyst for the synthesis of 2,3-dihydro-1H-perimidines

Research on Chemical Intermediates - This study focuses on covalent grafting of ZrO to β-CD to prepare an organic–inorganic hybrid material. The synthesised product was successfully...     

Catalyst‐Free One‐Pot Synthesis of Ketene Imines under Ultrasound Irradiation

An efficient and simple procedure for the synthesis of ketene imines via a one‐pot three‐component reaction of cyclohexyl isocyanide, diethyl acetylenedicarboxylate, and 1,4‐dihydropyridines under ultrasonic irradiation is described. The remarkable advantages are the simplicity of the experimental procedures, high yields, and short reaction times.     

Analysis of concrete labyrinth shielding and radiation dose for APF plasma focus neutron source by FLUKA Monte Carlo code

In this paper Monte Carlo simulations have been performed for the attenuation of neutrons radiation produced by a 4 kJ plasma focus device through labyrinth shielding design with various thicknesses. At the test site that will be fired with deuterium and deuterium fusion (D–D) resulting in a yield of about 10⁹ fusion neutrons of 2.45 MeV. This poses a radiological hazard to scientists and personnel operating the device. The goal of this study is to evaluate various shielding options under consideration for the plasma focus operating with D–D fusion. Shields of varying neutrons-shielding effectiveness were investigated using concrete materials. The most effective shield between labyrinth structure allowed almost 9.52E+6 shots per year while keeping personnel under 20 mSv of dose. The most expensive shield that is used labyrinth shield with 75 cm concrete thickness on the walls allowed almost 9E+8 shot per year.     

Kinetic C(2)-H exchange study ofcis-[(en)2Co(N-MeIm)OPO3H2]2+ by NMR: Evidence for the acidity of C(2)-H proton

The complexcis-[(en)₂Co(N-MeIm)OPO₃H₂]Br₂ (en=ethylenediamine, Me=methyl, Im=imidazole) has been synthesized from [(en)₂Co(N-MeIm)Br]Br₂, anhydrous AgCIO₄, and H₃PO₄ (0.85%), and characterized by¹H and¹³C nuclear magnetic resonance spectroscopy. C_(2)-H exchange in this complex was studied over the pD range from 9.40 to 12.80 at 60 °C, wherecis-[(en)₂Co(N-MeIm)OPO₃D]⁺ andcis-[(en)₂Co(N-MeIm)OPO₃]⁰ are the kinetically important species. The kinetic data may be interpreted in terms of an intramolecular interaction of the −OPO₃²⁻ group and H-2 in the coordinated N-MeIm.     

Chemoselective synthesis of 1,1-diacetates from aldehydes in the presence of Al(HSO<Subscript>4</Subscript>)<Subscript>3</Subscript> under mild solvent-free conditions

A novel efficient procedure has been developed for the preparation of acylals in high yields by reaction of the corresponding aldehydes with acetic anhydride in the presence of Al(HSO₄)₃ as catalyst under mild (room temperature) solvent-free conditions. Published in Russian in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 6. pp. 855–857. The text was submitted by the authors in English.     

A convenient one-pot synthesis of 3-amino-2, 5-dihydropyridazine and pyrimidine derivatives in the presence of high surface area MgO as a highly effective heterogeneous base catalyst

A new and efficient method for the preparation of 3-amino-2,5-dihydropyridazines from three-component reactions of (phenyl-hydrazono)-propan-2-one, aldehydes, and malononitrile or ethyl cyanoacetate in the presence of magnesium oxide (MgO) as a highly effective heterogeneous base catalyst is presented. Also, the three-component reactions of aldehydes, amidine systems, and malononitrile or ethyl cyanoacetate for the formation of 4-amino-5-pyrimidine carbonitrile and pyrimidinone derivatives, respectively, are investigated. The salient features of these methods include high conversions, short reaction times, cleaner reaction profiles, and the use of inexpensive and readily available catalyst.     

Epoxidation of vinyl cyanides by calcium hypochlorite under catalyst- and solvent-free conditions

In this paper, epoxidation of a wide range of alkenes by calcium hypochlorite (Ca(OCl)₂) was investigated under catalyst- and solvent-free conditions. It was noticed that the highest yield was achieved with crushing, when the reaction was between vinyl cyanides and Ca(OCl)₂. The structure of the synthesized epoxides was confirmed by IR, ¹H and ¹³C NMR and elemental analysis. Short reaction times, the use of a simple experimental procedure, and reducing of energy consumption are other important advantages of our work that could be mentioned too.     

A green protocol for chemoselective O-acylation in the presence of zinc oxide as a heterogeneous, reusable and eco-friendly catalyst

The solvent-free acylation of alcohols and phenols with acyl chlorides using ZnO as a catalyst is described. The remarkable selectivity under mild and neutral conditions, and recyclability of the catalyst, are advantages.     

Preparation and characterization of Fe3O4@Cu-β-CD as a hybrid magnetic catalyst for the synthesis of dihydropyrano[2,3-c]pyrazoles in H2O

Research on Chemical Intermediates - Fe3O4@Cu-β-CD is a hybrid composite with high catalytic activity. Easy separation with an external magnet and recyclability are the advantages of this...