Development of a spectrophotometric method for determination of ions Cu (II) C N- (2-hydroxybenzoyl) -N '- (p-tosil)hydrazine in ammonia media

A spectrophotometric method for the determination of Cu (II) ions with N- (2-hydroxybenzoyl) -N '- (p-tosyl) hydrazine (GBSH) in ammonia media has been developed. The optimal conditions for the formation of a complex compound are found: the wavelength of maximum light absorption; pH complexation; optimal time for color development; the amount of photometric reagent. Under optimal conditions of complexation of GBSG with Cu (Ⅱ) ions (λ = 401 nm, pH = 9.2, τ = 30 minutes, VGBSG = 3.75 ml), a calibration graph is constructed. The Bouguer-Lambert-Beer law is fulfilled in the range from 0.13 to 1.59 mg Cu (II) / 25 ml. The true molar light absorption coefficient of the complex compound of HBSG with Cu (Ⅱ) ions in the ammonia medium was 1480. The molar ratios in the solution of the complex compound were determined by the methods of saturation, shift of equilibria and conductometric titration - [Cu (Ⅱ)]: [HBSG] = 1: 1. According to Babko's method, the conditional constant of stability of the GBSG complex with Cu (Ⅱ) ions was calculated and it was 4.4 × 1010. The reproducibility and relative error of the developed photometric technique were determined by the method of mathematical statistics.

Configuration and isomeric composition of rubbers: determination by 1H and 13C NMR spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy is a convenient method for studying the structure and isomeric composition of diene rubbers. A simple and reproducible method is proposed for determining the content of both rubber and impurity compounds, which does not require additional sample preparation. Formulas for calculating the composition of industrial products and determining the initial substances are given, the applicability of the analysis method is confirmed. In the process of work, rubbers of various brands were analyzed, their configuration-isomeric composition was established. It was found that the integration ranges given in the literature earlier and the methods for processing 1H NMR spectra differ, the signals of the groups often overlap in the spectrum, which increases the calculation error. It is shown that the structure of the industrial products under study is established most accurately by carbon proton resonance spectroscopy, and the calculation based on the PMR spectra allows confirming the data obtained with sufficient accuracy.

EXTRACTION OF CHLORIDE AND THIOCYATE ACIDOCOMPLEXES OF METALS IN SALTING-OUT AGENT – MONOALKYLPOLYETHYLENE GLYCOL – WATER SYSTEMS

Distribution of iron (III), thallium (III, gallium, titanium (IV) chloride complexes in sodium chloride – synthanol DS-10 – water and ammonium sulfate – synthanol DS-10 – water systems, as well as iron (III), cobalt , nickel, cadmium and copper (II) thiocyanate complexes in the ammonium sulfate – synthanol DS-10 – water system investigated. It was found that the main influence on extraction is exerted by solution acidity and nature of the salting-out agent. The conditions for quantitative extraction of thallium (III) and gallium in the form of chloride complexes, as well as the conditions for maximum extraction of iron (III), zinc and cobalt thiocyanate complexes are established.

СОСТАВ, СТРУКТУРА И ЭЛЕКТРОХИМИЧЕСКАЯ АКТИВНОСТЬ СИЛИЦИДА ТИТАНА В РЕАКЦИИ ВЫДЕЛЕНИЯ ВОДОРОДА

The phase composition and structure of titanium silicide have been investigated by X-ray diffraction and X-ray spectral microanalysis methods. It has been found that the investigated silicide is a singlephase system consisting of a high-temperature TiSi2 modification with a rhombic face-centered lattice. The cathodic behavior of the TiSi2 electrode has been studied by the methods of polarization and capacitance measurements. It has been found that the cathodic potentiostatic curves of silicide in solutions of 0,5 M H2SO4; 0,5 M H2SO4 + 0,005 M NaF and1,0 M NaOHhave Tafel sections with slopes of 0,120; 0,097 and 0,109 V and they are characterized by the values of the hydrogen evolution overvoltage 0,90; 0,64 and 0,74 V (at i = 1 A/cm2), respectively. Titanium disilicide in sulfuric acid solution belongs to materials with a high overvoltage of hydrogen evolution, but in a fluoride-containing sulfuric acid solution and in an alkaline solution - to materials with a low overvoltage of hydrogen evolution. Based on measurements of the differential capacitance of the TiSi2 electrode (at f = 10 kHz), it has been concluded that a thin silicon dioxide film (Si + 2H2O → SiO2 + 4H+ + 4e–)is present on the surface of the silicide in the acidic fluoride-free electrolyte.

Pyridylimine palladium(II) complexes: one-pot synthesis and monoamine oxidase inhibition

An efficient one-pot synthesis of the cis-pyridylimine palladium (II) complexes is reported. The compo- sition and structure were proved by NMR, IR, X-ray, and elemental analysis. The monoamine oxidase inhibition activity of synthesized complexes, including six complexes previously unknown, were inves- tigated on native mouse brains. Some of the synthesized compounds: cis-dichlorido-2,6-dimethyl-N- ((pyridin-2-yl)methylene)anilinepalladium(II), cis-dichlorido-4-nitro-N-((pyridin-2-yl)methylene)- anilinepalladium(II), and cis-dibromido-2,6-di(propan-2-yl)-N-((pyridin-2-yl)methylene)aniline- palladium(II) inhibited monoamine oxidase with moderate activity (IC50: 13.09–17.66 μМ). None of the studied compounds showed cytotoxic activity against HEK-293 cell line (human kidney embryonic cells). Acute systemic toxicity assay, that is conducted by intraperitoneal injection of cis-dichlorido-4- nitro-N-((pyridin-2-yl)methylene)anilinepalladium(II) indicated low toxicity (LD50> 5000 mg / kg) for outbred stocks mice. Bioavailability was assessed by logP’s measurement.

On the extrema on the potential dependence of the charge transfer resistance in the hydrogen evolution reaction

The shape of the charge transfer resistance Rct versus overpotentialh curves for the hydrogen evolution reaction (Volmer – Heyrovsky mechanism, Langmuir isotherm for adsorbed hydrogen) was analyzed. It was shown that, depending on the kinetic parameters of reaction steps, three cases are possible: (i) there are no extrema on these curves; (ii) there is one maximum; (iii) there are a minimum and a maximum. Some ways for obtaining kinetic parameters from the curves with extrema are discussed. It was shown that the rate constants and transfer coefficients of all steps can be determined from logRct–h curve alone if there are a minimum and maximum of Rct in cathodic region. In the absence of the extrema, the amount of kinetic information gained from logRct–h plots is considerably reduced.

Preparation of metallic cobalt powders by thermolysis of cobalt (II) acetate, oxalate and formate

The thermal decomposition of cobalt (II) formate, acetate, and oxalate was studied by synchronous thermal analysis. It is established that in all cases the final product is metallic cobalt. Thermogravi- metric analysis combined with differential scanning calorimetry and mass spectroscopy made it possi- ble to establish thermolysis schemes and gaseous products of salt decomposition. The conditions for obtaining powdered metallic cobalt from carboxylic acid salts are determined. It was determined by electron microscopy that the particle size and structure of metal powders depend on the type of initial salt.

PRECIPITATION OF La (III), Sm (III) AND Tb (III) IONS BY ANIONOGENIC SURFACTANT ALKYBENZENESULFONIC ACID

The process of precipitation of La3+, Sm3+ and Tb3+ ions by anionic surfactant alkylbenzenesulfonic acid at various concentrations and ratios of components has been studied. The influence of the medium acidity and mixing time on the precipitation is considered. The resulting precipitates of rare earth elements ions with alkylbenzenesulfonic acid were studied by thermogravimetric, elemental and chemical analysis, and their composition was established. The conditional solubility products of the formed precipitates have been calculated. The optimal conditions for the precipitation of lanthanum (III), samarium (III) and terbium (III) ions with alkylbenzenesulfonic acid from aqueous solutions have been established.

Passivation of chromium disilicide in acidic media

The anodic behavior of CrSi2 electrode in 0,5 M H2SO4, 0,5 M HClO4, 0,5 M HNO3 and 0,5 M HCl solutions has been studied by the methods of polarization, capacitance, and impedance measurements. It has been concluded that in the process of anodic oxidation at potentials from corrosion E to transpassivation E inclusive, an oxide film is formed on the surface of chromium disilicide in the studied media, which is close in composition to SiO2 (with a small content of chromium oxides). The presence of this film on the silicide surface determines its high chemical resistance in the studied solutions. The thickness of the oxide film on CrSi2 has been calculated depending on the potential and composition of the electrolyte. The growth constant of the oxide film has been determined.

Extraction of macro quantities of scandium (III) in antipyrine-benzoic acid-water segregate system without the use of organic solvents

The optimal conditions of separation of aqueous system containing antipyrine, benzoic acid, hydrochloric or nitric acids, inorganic salting-out agents, and water at 85 ° C have been determined. The resulting organic phase contains the antipyrinium benzoate salt, which is a phase former. It is shown that the concentration of hydrochloric and nitric acids in the range of 0,01–0,20 mol/l promotes the stratification of the system, and above 0.4 mol l leads to homogenization. The conditions for the quantitative or maximum extraction of macroquantities of scandium (III) in the studied systems were found and their extraction capacity was determined. Inorganic salting-out agents provide separation even in the presence of 0,5 mol/l hydrochloric or nitric acid, while the degree of extraction of scandium (III) ions is significantly increased.