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The reactions of humic acids in a pure form and in the composition of coal with sodium percarbonate occurring on solid-phase mechanochemical treatment were compared. Analysis for CHNO, IR spectroscopy, and potentiometric titration were used to study changes in the composition of humic acids mechanochemically treated after isolation from brown coal. The sorption properties in relation to heavy metal ions (Zn2+, Cu2+, and Cd2+) and their changes as a result of the treatment were studied. The results were correlated with data similar to those for humic acids in coal that underwent mechanochemical treatment. It was demonstrated that, at present, an increase in the yield of humic acids and the concentrations of phenolic and carboxyl groups in brown coal as a result of treatment with sodium percarbonate can be explained by the oxidation of fractions other than humic acids in the organic matter of brown coal. [ABSTRACT FROM AUTHOR]

Dipinodiazafluorenes are hybrid nopinane-annelated heterocycles whose molecules include a heterocyclic core of 4,5-diazafluorene fused with fragments of terpene hydrocarbon; they can selectively extract palladium (88−100%), gold (42−96%), and ruthenium (8−19%) by single extraction from acidic aqueous solutions (pH 1.2) containing complex mixtures of 3d elements and noble metals. [ABSTRACT FROM AUTHOR]

N,N′-Bis(2-hydroxyiminoalkyl)-α,α′-dinitrones are of interest for the synthesis of 1,1′-dihydroxy-2,2′-biimidazoles. Thermal decomposition of two these dinitrones was studied in helium atmosphere. Thermal decomposition of the studied dinitrones at temperature interval 20–500 °C consists of several steps, the first step accompanying with significant exothermic effect (700–1000 J g−1). The first step has been shown to be a two-stage process, and decomposition products have been determined using chromatography–mass spectrometry. Thermogravimetric curves were used for the kinetic studies. Kinetic parameters of decomposition are estimated within the approaches of non-isothermal kinetics ("model-free" kinetics and nonlinear regression methods), with the computer program Netzsch Thermokinetics 2. [ABSTRACT FROM AUTHOR]

Abstract: The solid-phase reaction of sodium percarbonate with brown coal was investigated. The results of determining the effect of a peroxide component of sodium percarbonate on an increase in the yield of humic acids as a result of the reaction are presented. It was found that the mechanism of radical oxidation makes a significant contribution to the course of the reaction. Changes in the structure of humic acids because of oxidation in the mechanochemical reaction of brown coal with sodium percarbonate were studied by IR spectroscopy and elemental analysis. An increase in the concentration of phenolic and carboxyl groups in the structure of humic acids from brown coal after the reaction was caused by the appearance of new groups as a result of oxidation and their release due to the destruction of stable complexes with metals. [ABSTRACT FROM AUTHOR]

We propose a method for the determination of boron in aliphatic and aromatic trifluoroborates (including perfluorinated ones), ethers, and organoboron compounds containing dioxoborolane fragments, pyridine, and pyrazole rings, and triple bonds. The substances were decomposed by the oxygen flask combustion method. Boron was determined on an Agilent 4100 microwave plasma-atomic emission spectrometer. A number of organic compounds were analyzed, and the mass fraction of boron was determined with an error less than ±0.3 abs. %. [ABSTRACT FROM AUTHOR]

The presented analysis methods (automatic and gravimetric) are used to determine the main composition of various organic functional materials such as paramagnetic chelating agents for the synthesis of molecular magnetics, polyfluoroaromatic compounds for the preparation of special latices, new antivirus and analgesic agents, photoinitiator compounds for cationic polymerization, fluorophores for organic light emitting diodes, and so on. Conditions for the quantitative formation of final products of the complete decomposition of the compound (CO, HO, N, SO) are shown: the application of special oxide catalytic compositions and also the use of selectively adsorbing reagents for the removal of compounds hindering the determination of organogenic elements. Their determination error does not exceed ±0.3 % abs. [ABSTRACT FROM AUTHOR]

Procedures for the extraction-spectrophotometric determination of selenium in organoselenium compounds using a new reagent, 1,2-diamino-3,4,5,6-tetrafluorobenzene (DAFB), and a known reagent, 2,3-diaminonaphthalene (DAN), are developed. Complexes of DAFB or DAN with selenium(IV) are extracted with toluene, and the absorbance of the extracts is measured. The optimal conditions for the determination were found, and the spectrophotometric characteristics were determined. The calibration curves are linear in the range of selenium concentrations of 1-10.6 mg/L (DAFB) and 1-9.1 mg/L (DAN). Nitrogen, chlorine, bromine, fluorine, and sulfur present in organoselenium compounds do not interfere with the determination of selenium. The relative error of determination does not exceed ±2%. [ABSTRACT FROM AUTHOR]

Infrared spectra of humic acids have been studied using the IR-EXPERT computer system and database developed in the Novosibirsk Institute of Organic Chemistry. The information on the closest spectral analogues, their structures, and most probable structural fragments present in humic acid samples from Siberian peats and soils has been obtained. [ABSTRACT FROM AUTHOR]

set of specially selected classic and automated elemental analysis techniques was used to determine with a required accuracy the composition (C, H, N, Cl, Br, F, Ti, Fe) of transition metal complexes employed in post-metallocene catalytic systems. The element determination was in error by ±0.3-0.5 abs.%. Molecular weights of the synthesized oligomeric ligands were measured within the accuracy of 0.2-2.6 rel.% using the vapor-phase osmometry. [ABSTRACT FROM AUTHOR]

Results of many years’ worth of studies on the determination of carbon, hydrogen, and nitrogen on automated CHNS analyzers were summarized. Catalytic oxide compositions were selected that allow for the analysis of synthetic and natural organic compounds and materials of any elemental composition and structure: polycyclic, condensed aromatic, heterocyclic, carbonaceous (graphites and carbons), organometallic, organoelement, etc. [ABSTRACT FROM AUTHOR]

Quantitative and qualitative changes in humic acids of meadow soddy soils, occurring under the action of various fertilizer systems, were studied by C and P NMR. [ABSTRACT FROM AUTHOR]

comparative study of elemental composition, thermal characteristics, and IR and NMR spectra of humic acids recovered from modern and fossilized soils was made. The results obtained allow reconstruction of trends in variation of the environmental conditions in the course of soil formation at lake depressions in the Khakassia over a period from 3400 to 850 years before present day. [ABSTRACT FROM AUTHOR]

Separation of a mixture of naphthalene derivatives by reversed-phase high-performance liquid chromatography with UV detection was studied. Chromatographic characteristics were calculated for nine compounds, including naphthalene. [ABSTRACT FROM AUTHOR]