A facile synthesis of novel triazoloquinoxahnones and triazinoquinoxalinones

A series of 1-aryl-s-triazolo[4,3-a]quinoxalin-4-ones, 3 , were synthesized via the pyrolysis of the corresponding hydrazones, 6 . Thus, the cyclodehydrogenation occurred by refluxing them in an inert solvent (e.g. ethylene glycol) to give the triazoloquinoxalin-4-ones in a satisfactory yield. Using DMSO as a solvent for the above transformation afforded as a minor by-product an S-ylid. In contrast to earlier findings, annelation of a six-membered ring was successful and achieved through the pyrolysis of the pyruvate hydrazones derived of the quinoxalin-4-ones at ?230° to give the as-triazino[4,3-a]quinoxalin-5-ones, 4 . The reaction of 5 with acetylacetone afforded 3-(3′,5′-dimethylpyrazol-1-yl)-2(1H)-quinoxalinone, 10 . The structural assignments for the new compounds were based on their elemental analysis and spectroscopic data as well as an independent synthesis.     

Membranes obtained by preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene–perfluorovinyl ether)

Some properties of the membranes obtained by preirradiation grafting of acrylic acid onto poly(tetrafluoroethylene-perfluorovinyl ether) copolymer (PFA) films have been investigated. The dimensional change caused by grafting and swelling behavior, water uptake, electrical conductivity, and mechanical properties of the grafted films were found to increase as the grafting proceeds. The influence of the preparation conditions (such as preirradiation dose, monomer concentration, grafting temperature, and film thickness) on those properties was studied. These properties were found to be dependent mainly on the degree of grafting regardless of grafting conditions, except at higher monomer concentration (>40 wt %). The electric conductivity and mechanical properties for the membranes obtained at higher AAc concentrations were lower than those obtained at lower ones. Analysis by x-ray microscopy of the grafted films revealed that the grafting begins at the part close to the film surface and proceeds into the central part with progressive diffusion of monomer to give finally homogeneous distribution of the electrolytes in the whole bulk of the polymer. The membranes show good electrochemical and mechanical properties which make them acceptable for practical use as cation-exchange membranes.     

Novel ternary cobalt(II) and nickel(II) complexes of N-phthaloylglycinate. Synthesis, characterization and X-ray crystal structure

A new series of N-phthaloylglycineate (N-phthgly) ternary complexes of cobalt(II) and nickel(II) with imidazole (imi), N-methylimidazole (mimi) and 2,2′-bipyridyl (bipy) have been synthesized and characterized by elementary analyses, IR spectroscopy, thermogravimetric analysis. X-ray crystal structure analyses of the three complexes of [Co(mimi)₂(N-phthgly)₂] (1), [Co(bipy)(OH₂)₄](N-phthgly)₂ (2) and [Ni(imi)₂(N-phthgly)₂(OHCH₃)₂] (3) were also carried out. In complex (1), the Co(II) exists in a distorted tetrahedral enviroment, where two nitrogen atoms of two methylimidazole molecules and two oxygen atoms of the carboxylate group of two N-phthaloylglycinate molecules are coordinated. On the other hand, in complex (2) the cobalt atom coordinates a 2,2′-bipyridine molecule and four water oxygen atoms forming a distorted octahedral conformation. A molecule of N-phthaloylglycinate is connected by van der waals contact and H-bonds. For complex (3), the nickel atom is surrounded by four oxygens (two oxygens of two different N-phthaloylglycinate molecules and two of methanol ligand) in the basal plane of octahedron along with two imidazole nitrogen atoms at the apical positions. Strong intramolecular H-bond exists between the uncoordinated carboxylic oxygen of the N-phthaloylglycinate ligand and the O–H of the methanol group.     

Critical micelle concentrations for alkyltrimethylammonium bromides in water from 25 to 160°C

Critical micelle concentrations were determined by conductance measurements for decyl-, dodecyl-, tetradecyl- and hexadecyltrimethylammonium bromide in water at 25, 60, 95, 130, and 160°C. The results are discussed in terms of the equilibrium model and the nonlinear Poisson-Boltzmann model for micelle formation. The free energies of transferring a methylene group from water to the oil-like interior of the micelle are found to be –781 at 25°C, –796 at 60°C, –819 at 95°C, –815 at 130°C, and –787 at 160°C cal-mol^–1.     

Nonlinear instability of superposed magnetic fluids in the presence of an oblique magnetic field

The nonlinear evolution of interfacial waves separating two magnetic fluids subjected to an oblique magnetic field is studied in two dimensions, with the use of the method of multiple scales. It is shown that the evolution of the envelope is governed by two partial differential equations. These equations can be combined to yield two alternate Schrödinger equations with cubic nonlinearity; one of them leads to the determination of the cutoff wave number separating stable from unstable deformations while the other Schrödinger equation is used to analyze the stability of the system. The stability of the system is discussed both theoretically and computationally, and the stability diagrams are obtained. It is found in the linear theory that the oblique magnetic field has a stabilizing influence if 0 ₁ + ₂ < /2, or 3/2 < ₁ + ₂ 2 and a destabilizing influence if /2 < ₁ + ₂ < 3/2, where 0 _j , (j=1, 2) and , is the angle between the field and the horizontal axis.In the nonlinear theory, the stability analysis reveals that there exist different regions of stability and instability. It is reported that the oblique magnetic field plays a dual role in the stability criterion and the angles ₁ and ₂ play a distinctive role in this analysis besides the effect of the variation of the magnetic permeabilities.     

Radiation grafting from binary monomer mixtures. I. Vinyl ether of monoethanolamine and vinyl ether of ethyleneglycol

Gamma-radiation grafting of vinyl ether of monoethanolamine and vinyl ether of ethyleneglycol (VEEG) on polyethylene films has been studied from binary monomer mixtures. The effect of co-monomer composition and total exposure radiation dose on the grafting process is investigated. A combination of potentiometric and gravimetric techniques is applied to determine the grafting degree of each monomer in the final graft copolymer. The presence of more active monomer VEEG in the mixture was found to enhance the grafting of both monomers because the increasing of copolymerization rate which in turn increases the total grafting degree. The modification of the hydrophilic properties of the graft copolymer is studied by examining the grafted films for water- and copper (II) ions uptake.     

Catalytic kinetic determination of ultratrace amounts of ruthenium(III) based on the oxidation of hematoxylin by hydrogen peroxide

A new catalytic method was described for the determination of ruthenium(III) based on its catalytic effect on the oxidation of hematoxylin by hydrogen peroxide in weakly acidic medium. The reaction was followed spectrophotometrically by measuring the absorbance of hematoxylin at 440 nm. Under the optimum conditions, ruthenium(III) can be determined in the range 5–120 ng/ml with a relative standard deviation of 1.1%. The mean value of reaction rate constant was 0.012±0.04 min^–1 and the activation energy was 10.45 kJ/mol. The method was tested for the determination of ruthenium(III) in some synthetic mixtures.     

Thermal and electrical behaviour of nickel(II) and copper(II) complexes of 4-acetylamino-2-hydroxy-5-methylazobenzene

The thermal behaviour of the entitled nickel(II) and copper(II) complexes of ¯4-acetylamino-2-hydroxy-5-methyl azobenzene has been studied by means of differential thermal analysis (DTA), thermogravimetry (TG), X-ray powder diffraction, IR and electrical conductivity. A light has been thrown on the nature of interaction of the solvents of crystallization with the host complex. Some of the kinetic parameters are calculated and discussed.     

Enaminones in heterocyclic synthesis: Synthesis and chemical reactivity of 3‐anilino‐1‐substituted‐2‐propene‐1‐ one

The 3‐anilinoenones 3a,b were prepared from the corresponding 3‐dimemyl‐aminopropenones. The reactivity of 3a,b towards a variety of carbon and nitrogen nucleophiles as well as naphthoquinones is reported.     

Carbon‐based Nanosensors for Salicylate Determination in Pharmaceutical Preparations

Thiourea derivative‐based carbon paste electrode (TUD1‐CPE) was constructed as a potentiometric sensor for the determination of salicylate anion in pharmaceutical formulations, Aspocid® and Aspirin®. The optimized CPE contained 45.5 % graphite, 0.5 % reduced graphene oxide (rGO), 46.0 % nitrophenyl octyl ether (NPOE) plasticizer, 5.0 % TUD1 ionophore, and 3.0 % tridodecylmethyl ammonium chloride as additive. The incorporation of NPOE of high dielectric constant, and rGO in electrode caused better performance of the sensor; Nernstian response of 59.0 mV decade^?1 in the concentration range of 10^?1–10^?5 mole L^?1, a detection limit of 1×10^?5 mole L^?1 in a very short response time of 6 seconds. The prepared sensor showed high selectivity against similar anions (i. e. , benzoate, I^?, SCN^?). Selectivity was confirmed by calculating the formation constant (K_β) using sandwich membrane method, where K_β for TUD1‐salicylate is 10^0.43. Theoretical calculations at DFT‐B3LY/6‐31G** level of theory were performed to find interaction mechanism, Energies of HOMO and LUMO orbitals, non‐linear optical (NLO) properties (the electronic dipole moment (μ), first‐order hyperpolarizability (β), the hyper‐Rayleigh scattering (β_HRS) and the depolarization ratio (DR)), and other global properties; these calculations showed lower values of β and DR, higher value of β_HRS, and the shortest lengths of the four N?H bonds between TUD1 and salicylate which confirm their strong complexation and salicylate‐selectivity. Also, all the studied anion‐TUD1 exhibited relatively high NLO properties, and these results were considered as a preliminary study for investigating new types of NLO bearing materials. The sensors were applied successfully for the determination of salicylate anion in Aspocid® and Aspirin®.