Calculation of normal vibrations as applied to the study of properties of inorganic compounds

Using the Morse potential and spectroscopic constants it has been shown for diatomic molecules that the force constant of the bond (Kq) is proportional to its dissociation energy (D) so that Kq can be regarded as a measure of the bond strength. An analysis of K_MA of a series of complexes clearly indicates the correlation between the force constants K_MA and the MA bond length, thermodynamic constants of the MA bond dissociation, and reaction rates of the MA bond rupture.     

Formation of various types of intergranular bond during the compaction of ultra-high-molecular-weight polyethylene reactor powders

The results of mechanical testing of compacted ultra-high-molecular-weight PE reactor powder in air and in adsorption-active liquid environments, which dramatically reduce the interfacial surface energy, were analyzed. The intergranular character of brittle fracture of the samples in air and in decane made it possible to assess the contribution from cohesive intergranular bonds to the overall strength (～75%). It was shown that the formation of intergranular bonds depends on the intensity of molecular mobility in the polymer. The strength of the compacted material was found to be determined to a great extent by the deformation of the boundary layers in contacting grains. The formation of the intergranular layers can be accompanied by such a deep structural rearrangement in the nascent material that the structure of the intergranular layers upon the compaction of various reactor powders with different physical-and-mechanical characteristics becomes approximately the same.     

Formation of the pore structure in xerogel films based on ultra-high-molecular-weight polyethylene and multiwall carbon nanotubes

The fundamental aspect of the pore structure formation in composite films based on ultra-high-molecular-weight polyethylene and multiwall carbon nanotubes were studied by IR spectroscopy, mercury porosimetry, scanning electron microscopy, and differential scanning calorimetry in relation to the degree of filling.     

Solid state reactivity of organic compounds with inorganic compounds II.

Cobalt acetate reacts with aniline, 2-, 3- and 4-chloroanilinehydrobromides in the solid state to give the products CoBr₂. 2 amine in which the acetate is replaced by bromide and the amine gets attached to the metal in a concerted step. The products have been identified by elemental, spectral and thermoanalytical methods. The kinetics of these reactions have been studied by the mass loss method. The values of energy of activation are 142.0, 41.0, 77.0 and 71.4 kJ mol^?1. The greater reactivity of 2-chloro is due to ortho effect. An intermediate adduct (RNH₃)₂(Co(CH₃COO)₂Br₂) has also been characterized.     

Catalytic action of polyazopolyarenes in the liquid-phase oxidation of cumene

Conclusions A study was made of the kinetics of the oxidation of cumene in the presence of some polyazopolyarenes of the chrysoidine series.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 602–609, March, 1973.     

Cumyl hydroperoxide decomposition under the action of group II metal compounds

Cumyl hydroperoxide decomposition in chlorobenzene in the presence of magnesium, zinc, cadmium, or mercury 2-ethylhexanoate has been investigated. It has been established and kinetically proved that the decomposition reaction is preceded by the formation of a hydroperoxide-catalyst complex. Thermodynamic parameters of this complexation have been determined. The catalytic activity of the salts correlates with the ionization potentials of the metals.     

Multicentered self-immobilized ethylene polymerization catalysts based on functionalized titanium halide salicylaldiminate complexes for the synthesis of ultra-high-molecular-weight polyethylene

Specific features of ethylene polymerization using a new group of catalytic systems based on ten methylalumoxane-activated titanium halide salicylaldiminato complexes functionalized with ??-vinylalkoxy groups and containing tert-butyl substituents in the phenoxide moiety were studied. The catalytic activity of the new group of activated complexes is strongly affected by the position of the ??-vinylalkoxy functional group and by the number and position of substituents in the phenoxide moiety. These factors determine the ratio of the homogeneous and heterogeneous steps of the polymerization as a result of the catalyst self-immobilization onto the polymer formed, and also the molecular characteristics of the polymer obtained at 20, 40, and 60°C and ethylene pressure of 0.4 MPa. The possibility and conditions of preparing ultra-high-molecular-weight polyethylene with improved morphology were revealed.     

Analysis of the intensities of the longitudinal acoustic vibrations inn-alkanes and polyethylene

Summary Simple theoretical considerations indicate, that the integral intensity of the longitudinal acoustic modes (LAM) in the Raman spectrum ofn-alkanes should be independent of the chain length. The experiment in fact confirms this expectation. Using this property it becomes possible for polyethylene samples, to derive from the measured LAM-intensity the mass fraction of all-turns sequences contributing to this band. For solution crystallized samples this fraction coincides with the crystallinity, whereas in melt crystallized samples it generally turns out as smaller. The observed difference is likely to be due to the occurrence of local conformational defects (kinks, chain torsions) which interrupt the all-turns sequences within the crystallites. Temperature dependent experiments speak in favour of a defect creation for temperatures above 70°C.

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Zusammenfassung Mit Hilfe einfacher theoretischer Betrachtungen läßt sich zeigen, daß die integrale Intensität der longtudinal-akustischen (LA-) Schwingungen bein-Alkanen unabhängig von der Kettenlänge sein sollte, was durch Messungen tatsächlich als richtig bestätigt wird. Ausgehend von diesem Ergebnis ist es möglich, für teilkristallines Polyäthylen allein aus der Intensität der LA-Schwingung den Anteil der zugehörigen kristallinen all-turns Sequenzen zu bestimmen. Bei lösungskristallisierten Proben entspricht dieser Anteil genau der Kristallinität, bei schmelzkristallisierten Proben liegt er hingegen deutlich darunter. Ursache für diese Abweichung sind wahrscheinlich lokale Konformationsstörungen von Kinken und Torsionsfehlern, welche die all-turns Sequenzen im Kristall unterbrechen. Temperaturabhängige Experimente weisen deutlich auf ein Bestehen derartiger Defekte bei Temperaturen oberhalb von 70°C hin.

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Dedicated to Prof. Dr. G. Rehage on the occassion of his 60th birthday.

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With 7 figures and 4 tables     

Transformation of aromatic compounds under the action of the basidiomycetesPhanerochaete sanguinea andCoriolus villosus

The pathways of the transformation of some aromatic compounds by rhe basidiomycetesPhanerochaete sanguinea andCoriolus villosus have been studied. It has been shown that the degradation of these compounds has an oxidative nature and depends on the type of substituents in the benzene ring and the propane chain. A difference has been found in the mechanisms of the reactions of the two fungi that is a consequence of the different compositions of their enzyme complexes.     

DTA study of the reactions of non-metal fluorides with inorganic compounds

On the basis of the calculated Gibbs energy change for the standard state, the possibility of carbon tetrafluoride, silicon tetrafluoride, dichlorodifluoromethane and sulfur hexafluoride reacting with a number of elements and their compounds was evaluated. The reactions were studied by differential thermal analysis. Fluorination reactions of metals and oxides with dichlorodifluoride were investigated, and the temperature conditions of the syntheses were determined by measuring the temperature at the start of interaction (t _si.).The existence of a correlation betweent _si.) andH _formation ^o for the fluorinating agents was assumed, and a sequence of the fluorinating power of the non-metal fluorides was established. The perspectives of using non metal fluorides in the synthesis of inorganic fluorides are discussed.

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Zusammenfassung Auf Grund der berechneten Gibbsschen Energieänderungen des Standardzustandes wurde die Möglichkeit von Reaktionen zwischen Kohle und Silikontetrafluorid, Dichlordifluormethan, bzw. Schwefelhexafluorid, sowie einer Anzahl von Elementen und ihrer Verbindungen ausgewertet. Das tatsächliche Zustandekommen der Reaktionen wurde durch Differentialthermoanalyse untersucht. Fluorierungsreaktionen von Metallen und Oxiden mit Dichlordifluormethan, Silikontetrafluorid und Schwefelhexafluorid wurden untersucht und die Temperaturbedingungen der Synthesen durch Messungen der Temperatur am Anfang der Wechselwirkung (t _s.i) bestimmt.Unter Annahme der Existenz einer Korrelation zwischent(_s.i), undH _Bildung ^o der fluorierenden Substanzen wurde eine Sequenz des Fluorierungsvermögens der Nicht-Metallfluoride aufgestellt. Die Perspektive der Anwendung von Nicht-Metallfluoriden bei der Synthese anorganischer Fluoride wird erörtert.

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Résumé A partir des variations de l'énergie de Gibbs calculée à l'état standard, on a évalué la possibilité qu'il se produise une réaction entre le carbone et la fluorure de silicium, le dichlorodifluorométhane et l'hexafluorure de soufre ainsi que plusieurs éléments et leurs composés. Le déroulement effectif des réactions a été étudié par analyse thermique différentielle. Les réactions des métaux et oxydes avec le dichlorodifluorométhane, le tétrafluorure de silicium et l'hexafluorure de soufre ont été examinées et les températures où s'effectuent les synthêses ont été difinies en mesurant la température du début de réaction (t _s.i).En supposant l'existence d'une corrélation entret _s.i). etH _formation ^o pour les agents de fluoration, une séquence du potentiel fluorant des fluorures non-métalliques a été établie. La perspective de l'utilisation des fluorures non-métalliques pour la synthèse des fluorures inorganiques est discutée.

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Interactions of iodoperfluorobenzene compounds with gold nanoparticles

Understanding the interactions of small molecules with gold nanoparticles is important for controlling their surface chemistry and, hence, how they can be used in specific applications. The interaction of iodoperfluorobenzene compounds with gold nanoparticles was investigated by UV-Vis difference spectroscopy, surface enhanced Raman spectroscopy (SERS) and Synchrotron X-ray photoelectron spectroscopy (XPS). Results from UV-Vis difference spectroscopy demonstrated that iodoperfluorobenzene compounds undergo charge transfer complexation with gold nanoparticles. SERS of the small molecule-gold nanoparticle adducts provided further evidence for formation of charge transfer complexes, while Synchrotron X-ray photoelectron spectroscopy provided evidence of the binding mechanism. Demonstration of interactions of iodoperfluorobenzene compounds with gold nanoparticles further expands the molecular toolbox that is available for functionalising gold nanoparticles and has significant potential for expanding the scope for generation of hybrid halogen bonded materials.     

Recent progress in the synthesis of inorganic nanoparticles

Nanoparticles probably constitute the largest class of nanomaterials. Nanoparticles of several inorganic materials have been prepared by employing a variety of synthetic strategies. Besides synthesizing nanoparticles, there has been considerable effort to selectively prepare nanoparticles of different shapes. In view of the great interest in inorganic nanoparticles evinced in the last few years, we have prepared this perspective on the present status of the synthesis of inorganic nanoparticles. This article includes a brief discussion of methods followed by reports on the synthesis of nanoparticles of various classes of inorganic materials such as metals, alloys, oxides chalcogenides and pnictides. A brief section on core-shell nanoparticles is also included.     

Determination of phenolic compounds in wastewater by liquid-phase microextraction coupled with gas chromatography

Liquid-phase microextraction (LPME) coupled with gas chromatography-flame ionization detection is applied to the analysis of phenolic compounds (phenol, o-cresol, m-cresol, 2,4-dimethylphenol, 2,3- dimethylphenol, and 3,4-dimethylphenol) in water samples. Experimental parameters affecting the extraction efficiency (including extraction solvent and drop volume, stirring rate, extraction time, temperature, salt concentration, and pH) are investigated and optimized. The developed protocol yields a good linear calibration curve from 5 or 20 to 10000 microg/L for the target analytes. The limits of detection are in the range of 0.94 to 1.97 microg/L, and the relative standard deviation is below 9.37%. The established method is applied to determine the phenolic pollutants in real wastewater samples from a coking plant. The recoveries of the phenolic compounds studied are from 92% to 102%, suggesting the feasibility of the LPME method for the determination of the phenolic compounds in wastewater.