Reaction of 4-Aryl-3-thiosemicarbazides with Phenylisothiocyanate: A Facile Synthesis of Thiazole,Pyrazole and Pyrimidine Derivatives

The reaction of 4-aryl-3-thiosemicarbazides 1a-d with phenylisothiocyanate gave the intermediate potasium salts 2a-d . The latter afforded 3a-d, 13a-d and 19 upon the reaction with phenacyl bromide, monochloroacetic acid and ethyl bromocyanoacetate respectively.     

Reaction of ethyl 2‐diazo‐4,5,6,7‐tetrahydrobenzo[b]thiophene‐3‐carboxylate with 3‐iminobutyronitrile: synthesis of pyridazines,thiophenes, and their fused derivatives

Reaction of ethyl 2‐diazo‐4,5,6,7‐tetrahydrobenzo[b]thiophene‐3‐carboxylate 1 with 3‐iminobutyronitrile 2 gave the hydrazone derivative 3 . The reactivity of the latter product toward a variety of chemical reagents as well as the biological activity of the newly synthesized products were studied. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:403–412, 2000     

Reactions of Benzoyl Isothiocyanate with Active Methylene Reagents: A Novel Synthesis of Thiophene,Thiazoline and Thieno[2,3-d]Pyrimidine Derivatives

Various derivatives of thiophene, thiazoline and thienopyrimidine have been synthesized via the reaction of active methylene reagents (la-j) with benzoyl isothiocyanate in the presence of potassium hydroxide, followed by the subsequent treatment of the potassium salt intermediates 2a-j with phenacyl bromide or ethyl chloroacetate. The stability of the formed adducts 3 and 12 or their selective cyclization depends on both the nature of the active methylene reagent and the α-halocarbonyl compounds.     

Using fractional-order integrator to control chaos in single-input chaotic systems

This paper deals with a fractional calculus based control strategy for chaos suppression in the 3D chaotic systems. It is assumed that the structure of the controlled chaotic system has only one control input. In the proposed strategy, the controller has three tuneable parameters and the control input is constructed as fractional-order integration of a linear combination of linearized model states. The tuning procedure is based on the stability theorems in the incommensurate fractional-order systems. To evaluate the performance of the proposed controller, the design method is applied to suppress chaotic oscillations in a 3D chaotic oscillator and in the Chen chaotic system.     

Simultaneous Determination of Nickel(II) and Copper(II) by Second‐Derivative Spectrophotometric Method in Micellar Media

A second‐derivative spectrophotometric method based on zero‐crossing over technique is developed in simultaneous determination of copper(II) and nickel(II) ions. Methylthymol blue (MTB) as a chromogenic reagent and cetyltrimethylammonium bromide as a surfactant were used, and measurements were carried out in buffered solution at pH 6 and at a temperature of 25 °C. The amplitude of derivative spectra was measured at wavelengths of 631.9 and 587.7 nm for the simultaneous determination of Ni²⁺ and Cu²⁺, respectively. Linearity was obtained in the range of 0.5–5.0 μg mL^?1 for both ions in the presence of 0.0–5.0 μg mL^?1 of the other ion as an interfering ion. IUPAC detection limits for Cu²⁺ and Ni²⁺ ions were obtained at 0.48 and 0.43 μg mL^?1, respectively. The proposed procedure has been applied successfully for the simultaneous determination of copper and nickel in synthetic binary mixtures and real samples.     

A robust synthesis and characterization of superparamagnetic CoFe2O4 nanoparticles as an efficient and reusable catalyst for green synthesis of some heterocyclic rings

A robust synthesis for magnetic CoFe₂O₄ nanoparticles via a hydrothermal technique was investigated. The prepared magnetic nanoparticles were characterized using powder X‐ray diffraction, scanning, transmission and high‐resolution transmission electron microscopies, energy‐dispersive X‐ray and infrared spectroscopies, thermogravimetric analysis and vibrating sample magnetometry. Based on the obtained data, the prepared powder was composed of ultrafine particles in nanometer size range with highly homogeneous spherical shape and elemental composition. Moreover, the prepared magnetic CoFe₂O₄ nanoparticles were used as an efficient catalyst for green synthesis of tetrahydropyridines and pyrrole derivatives in excellent yields, with easy work‐up and purification of products by non‐chromatographic methods. The catalyst can be recovered for subsequent reactions and reused without any appreciable loss of activity. Copyright © 2016 John Wiley & Sons, Ltd.     

Comonotonic stochastic processes and generalized mean-square stochastic integral with applications

The concept of monotonic stochastic processes was introduced by Skowroński [Aequationes mathematicae 44 (1992) 249–258]. In this paper, we intro     

Interfacial and Thermodynamic Properties of Formation of Water‐in‐Oil Microemulsions with Surfactants (SDS and CTAB) and Cosurfactants (n‐Alkanols C5–C9)

The interfacial and thermodynamic properties of water‐in‐oil microemulsion systems consisting of water, isopropyl myristate, n‐alkanol, and surfactant have been investigated using the method of dilution. The surfactants used were hexadecyl trimethylammonium bromide and sodium dodecylsulfate, and the cosurfactants were n‐alkanols with varying chain length from (C₅–C₉). The distribution of cosurfactant (n‐alkanol) between the interface of water and oil regions at the threshold level of stability as well as the energetics of the transfer of the cosurfactant from the oil to the interfacial region have been examined as a function of varying cosurfactant chain length (C₄–C₉) and temperature. The structural parameters (including dimension, population density and effective water pool radius) of the dispersed water droplets in the oil phase have also been evaluated and correlated with alkanol chain length.