PTSA catalyzed simple and green synthesis of benzothiazole derivatives in water

Abstract  

p-Toluenesulfonic acid (10 mol%) was found to be an effective and efficient catalyst for the synthesis of 2-substituted benzothiazoles from aromatic aldehydes and 2-aminothiophenol in moderate to excellent yields in water. This method provides a simple and efficient protocol in terms of mild reaction conditions, clean reaction profiles, small quantity of catalyst, and simple workup procedure.     

Effects of external electromagnetic field on binodal curve of (water + propionic acid + dichloromethane) ternary system

The effects of an external electromagnetic field on the binodal curve of the (water + propionic acid + dichloromethane) ternary system was investigated at 91.3 kPa and T = (294.15 and 284.15) K. The experimental binodal curve values for the ternary system were obtained by the cloud point method using a new setup with a flat capacitor. The effects of variation of frequencies and amplitude of voltages of the applied external electromagnetic field on the binodal curve results have been evaluated. The results obtained indicate that the heterogeneous two-phase area increases with increasing frequency of the applied external electromagnetic field. At constant frequency, a similar effect has been found by increasing the amplitude of the voltage of the applied external electromagnetic field. The comparison between the results obtained for this work with those reported in previous work indicates that the treatment efficiency in liquid–liquid extraction process of (water + propionic acid + dichloromethane) ternary system can be governed by the applied external electromagnetic field.     

Synthesis and characterization of nickel(II) complexes with three potentially hexadentate Schiff-base ligands and polyamines: X-ray crystal structure determination of one nickel(II) complex

Three new potentially hexadentate N₄O₂ Schiff-base ligands (H₂L¹, H₂L² and H₂L³) were prepared from the reaction of the polyamines N,N′-bis(2-aminophenyl)-1,2-ethanediamine (L¹), N,N′-bis(2-aminophenyl)-1,3-propanediamine (L²) and N,N′-bis(2-aminophenyl)-1,4-butanediamine (L³), respectively with salicylaldehyde. Reaction of the Schiff bases with Ni(II) salts in the presence of N(Et)₃ gave the neutral complexes [NiL⁴], [NiL⁵] and [NiL⁶]. Ni(II) complexes of the polyamines were also prepared. One of complexes [Ni(L¹)(MeCN)₂](ClO₄)₂·MeCN has been characterized through X-ray diffraction methods.     

A green and highly efficient alkylation of thiols in water

An environmentally benign and efficient process for the preparation of thioethers was developed by simple and practical reactions of alkyl halides and thiols in water in the presence of K₂CO₃ or Et₃N in very high yields. The reaction of aryl, alkyl, aliphatic and hindered thiols with various alkyl halides gave the corresponding products with significant advantages such as high conversions, short reaction time, mild reaction conditions, and low cost, simple workup with good to quantitative yields.     

Synthesis of Monodisperse Lanthanum Hydroxide Nanoparticles and Nanorods by Sonochemical Method

In this work, monodisperse nanoparticles and nanorods of lanthanum hydroxide was synthesized from the reaction of lanthanum(III) nitrate and sodium hydroxide by sonochemical method. The effect of some of the parameters such as feeding rate of precursors, different solvents of reaction, time of sonication, and various surfactants on the particle size and morphology of products was studied. The as-prepared products were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy.     

Investigation the effects of shear rate on stationary droplets coalescence by lattice Boltzmann

Coalescence is the process by which two or more droplets merge to form a single droplet. It can take place in many processes, ranging from meteorology to astrophysics. When two stationary droplets are suspended in a bulk vapor, if the gap between the droplets has been smaller than a critical value, the two droplets will coalesce. In this paper, single component, two phase flow is modeled under shear flow using a free energy lattice Boltzmann approach and the coalescence of stationary droplets are investigated for different cases of radius and shear rate. The results show that there is a critical gap between droplets and for the values larger than that they will not coalesce. Also in the case of constant thermophysical properties, this critical gap is a function of droplet radius and shear rate.     

Asymptotic normality of recursive estimators under strong mixing conditions

The main purpose of this paper is to estimate the regression function by using a recursive nonparametric kernel approach. We derive the asymptotic normality for a general class of recursive kernel estimate of the regression function, under strong mixing conditions. Our purpose is to extend the work of Roussas and Tran (Ann Stat 20:98–120, 1992) concerning the Devroye–Wagner estimate.     

Synthesis and characterization of two new fluorescent macrocycles: A novel fluorescent chemosensor for zinc ion

Two new macrocyclic systems (L¹, L²) containing two emissive naphthalene were synthesized and characterized. The macrocycles were studied by ¹H NMR, ¹³C NMR, COSY, HMQC, DEPT, microanalysis and mass spectroscopy. The influence of metal cations Na⁺, Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Hg²⁺ on the spectroscopic properties of the macrocyclic systems in acetonitrile/DMF 9:1 (v/v) mixtures were investigated by means of absorption and emission spectrophotometry. The macrocycle L¹ was found to be as an effective fluorescence sensor for Zn²⁺ ions. Zn²⁺ and Cd²⁺ ions show the most effects on the fluorescence intensity of L².     

New formulation and relaxation to solve a concave-cost network flow problem

In this paper we study a minimum cost, multicommodity network flow problem in which the total cost is piecewise linear, concave of the total flow along the arcs. Specifically, the problem can be defined as follows. Given a directed network, a set of pairs of communicating nodes and a set of available capacity ranges and their corresponding variable and fixed cost components for each arc, the problem is to select for each arc a range and identify a path for each commodity between its source and destination nodes so as to minimize the total costs. We also extend the problem to the case of piecewise nonlinear, concave cost function. New mathematical programming formulations of the problems are presented. Efficient solution procedures based on Lagrangean relaxations of the problems are developed. Extensive computational results across a variety of networks are reported. These results indicate that the solution procedures are effective for a wide range of traffic loads and different cost structures. They also show that this work represents an improvement over previous work made by other authors. This improvement is the result of the introduction of the new formulations of the problems and their relaxations.     

Second-harmonic generation from monolayer Langmuir–Blodgett films of various push–pull pyridine and terpyridine metal complexes

The new ligands (E)-4-[2-(4-(N-methyl-N-hexadecylaminophenyl)ethenyl]pyridine (L¹) and 4′-(C₆H₄-p-N(Me)(hexadecyl))-2,2′:6′,2″-terpyridine (L²) were prepared along with their complexes [cis-Ir(CO)₂ClL¹], [fac-Os(CO)₃Cl₂L¹], [ZnCl₂L²] and [IrCl₃L²]. Whereas these complexes show a large second-order nonlinear optical (NLO) response at the molecular level, similar to that of related organic alkylated salts as evidenced by the Electric Field Induced Second-Harmonic (EFISH) generation technique, their Langmuir–Blodgett (LB) film susceptibility is lower than that of the salts.