Course Of Thermolysis Research Articles

Luminescent Europium(III) Compounds with Quinaldic Acid

Heteroligand luminescent europium(III) complexes with quinaldic acid and neutral ligands were prepared. The compounds obtained were characterized by elemental analysis, X-ray diffraction, thermal gravimetric analysis, and IR spectroscopy. The composition of the complexes was determined. In the course of thermolysis, the nitrogen-containing ligand molecule is eliminated in one step with exo- and endothermic effects. The compounds are thermally stable up to 260°С. The synthesized coordination compounds were introduced into low-density polyethylene to obtain luminescent polymer materials.

Two sides of thermal stability of energetic liquid: Vaporization and decomposition of 3-methylfuroxan

Analysis of thermal behavior of liquids is often accompanied by vaporization. In an extreme case, the calorimetric (DSC) experiment reveals the only endothermic evaporation instead of the more valuable thermal decomposition. 3-Methylfuroxan (MMF) is an energetic monosubstituted 1,2,5-oxadiazole N-oxide that shows the above behavior. We investigate the sample mass and confinement effects and show that the pressure DSC allows observing thermal decomposition of target compound at 2.0 MPa. Advanced model-fitting kinetic analysis reveals two global stages, the first of which is a competition between the noncatalytic reaction and autocatalytic one, whereas the second global stage is a second-order reaction. Analysis of MMF thermolysis in solution in dibutyl phthalate shows the activation energy for noncatalytic reaction to be 145.4 ± 1.7 kJ mol−1. To resolve the gas decomposition products in experiments at 0.1 MPa pressure, where the evaporation is abundant, a gas chromatography–mass spectrometry coupled with thermal analyzer was used. Among the gases that are consistent with a furoxan ring rupture by CC and NO bonds (HNCO, CH3CN), we detect CH3COCN that retains CC bond. The formation of geminal cyanonitro compound in the course of thermolysis is proposed to explain the composition of the gas reaction products. Overall, with the range of thermal analysis tools (DSC, PDSC, GC–MS/TGA, thermokinetic modeling) we performed a detailed analysis of thermal transformations of unexplored simple monosubstituted furoxan. The applied methodological approaches could be transferred to other molecular liquids.

Thermolysis of Petroleum Pitch from Different Sources

The thermolysis of isotropic pitch prepared from heavy pyrolytic tar and heavy catalytic-cracking gas-oil is investigated. The basic properties of the isotropic pitch are investigated in the course of thermolysis at different temperatures. Optimal temperatures for thermolysis so as to obtain fibrous pitch are established: 350°C for isotropic pitch from heavy pyrolytic tar; and 400°C for isotropic pitch from heavy catalytic-cracking gas-oil. In both cases, the duration of thermolysis is 4 h. Then the formation of mesophase begins. Its content in the pitch after 6 h is 10%.

Thermal stability of irradiated solutions of 2,2′-bipyridine-6,6′-dicarboxylic acid bis(N-ethyl-4-hexylanilide) in fluorinated sulfones

The effect exerted by irradiation with accelerated electrons on the thermolysis kinetics in two-phase systems consisting of 14 M aqueous HNO3 and FS-13 diluent or 0.1 M solution of 2,2′-bipyridine-6,6′-dicarboxylic acid bis(N-ethyl-4-hexylanilide) in FS-13 was determined. Samples were irradiated at an electron accelerator at a dose rate of 10 kGy h–1 to integral doses of 0.1, 0.5, and 1 MGy. The mixtures were heated in an autoclave at 170 and 200°С. A study of the heat and gas evolution processes occurring in the course of thermolysis of extraction mixtures irradiated to doses of 1 MGy showed that conditions for the development of autocatalytic oxidation are not created even in the systems kept for 2 weeks in contact with 14 M HNO3.

Formation of C1-C4 alkanes in the course of alkali activation of brown coal

The yield of gaseous products from brown coal and brown coal-KOH compound was studied in relation to the thermolysis temperature. The compositions of the gases formed in the presence of alkali and without it were compared. The alkali affects the course of thermolysis of the organic matter of coal and favors an increase in the fraction of hydrogen and alkanes in the thermolysis gases.

Studying of liquid thermolysis products of various types of immature kerogen in sedimentary lacustrine rocks from the valjevo-Mionica basin, Serbia, and the effect of Pt4+ and Ru3+ ions on their yield and the hydrocarbon composition

Liquid thermolysis products of various types of immature kerogen from sedimentary lacustrine rocks from the Valjevo-Mionica basin in Serbia were studied to evaluate the generation potential of kerogen contained in the organic matter (OM) of the rocks, determine the composition of the biomarkers and alkylaromatics in the liquid thermolysis products, and elucidate the effect of Pt4+ and Ru3+ ions (which were added in the form of inorganic salts) on the yield and hydrocarbon composition of the liquid thermolysis products. For this purpose, representative bitumen-free samples A and B of the sedimentary rocks were subjected to thermolysis under various conditions. Rock A contains high amount of immature organic matter, which is dominated by kerogen type I/II and was generated under strongly reduced sedimentation conditions at a high salinity. Sample B is poorer in immature OM than sample A, and the OM of the former contains kerogen type II/III and was generated predominantly in a reduced environment. The content of the liquid products and the concentrations of hydrocarbons obtained in the course of thermolysis of bitumen-free sample A and the typical oil distribution of the biomarkers and alkylaromatics in the thermolysis products confirm a high generation potential of OM in this rock. In all of our experiments on the thermolysis of bitumen-free sample B, the yield of liquid products and hydrocarbons is low. According to the kerogen type, the thermolysis of this rock generates much gases. The Pt4+ and Ru3+ ions (added in the form of simple inorganic salts) increased the yield of liquid (kerogen type I/II) and gaseous (kerogen type II/III) products. During the thermolysis of various type of immature kerogen in the lacustrine sedimentary rocks at a temperature of 400°C, the OM attained maturation corresponding to the early catagenesis level. Saturated biomarkers and alkylaomatics in the thermolysis products of both samples display typical oil distributions. The type of the source OM most strongly affects the composition of n-alkanes and alkylnaphthalenes. The metal ions used in this research served as catalysts for the methylation process during the thermolysis of immature kerogen, regardless of its type. The effect of the Pt4+ and Ru3+ ions on other transformations of the hydrocarbons, for example, the destruction of high-molecular n-alkanes to low-molecular ones and on isomerization reactions in molecules of polycyclic biomarkers and alkylaromatics to thermodynamically more stable isomers in the thermolysis products is controlled, first of all, by the type of the source OM.

Comparative characterization of the distribution of biomarker hydrocarbons in the chemical transformation products of oxygen-containing precursors of petroleum

The distribution of biomarker hydrocarbons in the thermolysis and thermocatalysis products of oxygen-containing compounds (possible petroleum hydrocarbon precursors) was studied by gas chromatography-mass spectrometry. It was found that n-alkylcyclohexanes and steranes were generated in the course of thermolysis along with expected hydrocarbons—n-alkanes and isoprenes, which resulted from the loss of a functional group. In this case, the molecular-weight distributions of n-alkanes and n-alkylcyclohexanes correlated well with each other. In the course of thermocatalysis, the homologous series of n-alkanes and n-alkylcyclohexanes were also generated; however, an n-alkylcyclohexane distribution maximum had an even number of carbon atoms in the molecule (C18). It was experimentally found that the sterane fragments of oxygen-containing compounds formed upon thermolysis were thermodynamically unstable; this was supported by the formation of biological C27–C29 5α, 14α, 17α, 20S, and 20R and 5β, 14α, 17α, and 20R (coprostane) steranes as a result of thermolysis. Unlike thermolysis, all of the four epimers of regular C27–C29 (5α, 14α, 17α, 20S, and 20R and 5α, 14β, 17β, 20S, and 20R) steranes were formed as a result of thermocatalysis. It was found that the relative distribution of biomarker hydrocarbons in the thermolysis products of various oxygen-containing compounds largely reflected the structure of the parent organic substance, as compared with that upon thermocatalysis in the presence of active aluminosilicate.

On the role and transformations of components of intumescent fire-retardant paint-and-varnish formulations in the course of thermolysis

Main components of fire-retardant intumescent paint-and-varnish formulations, such as pentaerythritol, melamine, and ammonium phosphate, were considered in detail. A comprehensive thermal study of these components was carried out, including thermogravimetric and differential thermal analyses. A mechanism of transformations of these substances in the course of thermal degradation is described.

Effect of Precipitation pH and Heat Treatment on the Properties of Hydrous Zirconium Dioxide

The effect of the precipitation pH and subsequent heat treatment is studied on the properties of hydrous zirconium dioxide precipitated by ammonia from nitrate solutions. Precipitation at pH ≤ 6 generates hydrous zirconium dioxide, which contains excess sorbate nitrate ions; the product precipitated at pH ≥ 7 contains excess ammonium ions. This distinction considerably affects the course of thermolysis and the morphology of products. The exotherm associated with the formation of the crystal structure of zirconia becomes more pronounced with rising precipitation pH. In addition, the samples prepared at pH ≥ 7 have a more developed surface. The morphologic and microstructural evolution of hydrous zirconium dioxide samples during thermolysis is described.

Thermolysis of RAFT‐Synthesized Poly(methyl methacrylate).

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Thermolysis of RAFT-Synthesized Poly(Methyl Methacrylate)

Thermolysis provides a simple and efficient way of eliminating thiocarbonylthio groups from RAFT-synthesized polymers. The course of thermolysis of poly(methyl methacrylate) (PMMA) prepared with dithiobenzoate and trithiocarbonate RAFT agents was followed by thermogravimetric analysis (TGA), 1H NMR spectroscopy, and gel permeation chromatography (GPC). The weight loss profile observed depends strongly on the RAFT agent used during polymer synthesis. PMMA with a methyl trithiocarbonate end group undergoes loss of that end group at ~180°C, at least in part, by a mechanism believed to involve homolysis of the C–CS2SCH3 bond and subsequent depropagation. In contrast, PMMA with a dithiobenzoate end appears more stable. Only the end group is lost at ~180°C and the dominant mechanism is proposed to be a concerted elimination process analogous to that involved in the Chugaev reaction.

Development of the specific surface areas of natural coal in the course of thermolysis in the presence of potassium hydroxide

The development of the surface of natural coal from Donets field in the course of thermolysis with KOH was studied. The dependences of the specific surface area of coal containing 90% carbon on the activation time, temperature (400–800°C), and KOH/coal ratio (0.75–4.5 g g−1) were determined. The effect exerted on the development of the porous coal structure by low-temperature (20±2°C) oxidative modification causing formation of oxygen functional groups and reorganization of the coal three-dimensional structure was studied.

Analysis and prediction of the Arrhenius parameters of low-temperature thermolysis of nitramines by means of the [formula omitted] spectroscopy

The paper presents 15 N NMR chemical shifts δ of 24 nitramines out of which 1-nitro-1-azaethylene, 1,3-dinitro-1,3-diazacyclobutane and 1,3,5,7,9-pentanitro-1,3,5,7,9-pentaazacyclodecane have not been synthesized yet. The relationships between the Arrhenius parameters E a and log A of the low-temperature thermolysis under conditions of Russian manometric method and δ values of nitrogen atoms in nitro groups are specified for substances studied. The δ values correspond to nitro groups in nitramino groupings which are the first to undergo thermolysis. On the basis of the relationships specified the E a and log A values are predicted for 13 compounds from the nitramines studied, the parameters of homolytic course of thermolysis are differentiated from those of bimolecular or another heterolytic thermal decomposition, some aspects of the thermolysis of nitramines, particularly with geometrical constraints and/or with strongly-withdrawing groups in their molecules, are interpreted and evaluation of effect of solid–liquid phase transition on the kinetics of initial stage of HMX thermolysis are made.

Tantalum(V) alkoxides : Electrochemical synthesis, mass-spectral investigation and oxoalkoxocomplexes

Ta(OR) 5 (R = Me( 1), Et( 2), Bu n( 3)) and Ta 2O(OPr i) 8·Pr iOH ( 4) were obtained by the anodic oxidation of metallic tantalum in absolute alcohols in the presence of LiCl (electroconductive additive). Ta(OPr i) 5 ( 5) was isolated by distillation in the course of thermolysis of 4 under reduced pressure. Ta(OC 2H 4OMe) 5 ( 6) was obtained by reaction of 5 with 2-methoxyethanol. Compounds 1 and 5 are isostructural with the corresponding [Nb(OR) 5] 2 (R = Me,Pr'); their molecules involve two [M0 61 octrahedra sharing a common edge. Recrystallization of 1 from McOH at < 20°C resulted in the isolation of a monosolvate Ta(OMe) 5·MeOH. The solubility of Ta(OMe) 5 in . was studied in the temperature range of −80°C to 50°C. The dinuclear molecule 4 has one, μ-O(oxo) and one μ-OR group, ROH is in an axial position. Compound 4 is the first example of a stable oxoalkoxide (in solution and gas phase) with as few as two metal nuclei, in contrast to most M x O x (OR) z , which are usually of higher nuclearity. Crystalline Ta709(OPr i) 17 ( 7) was obtained by the uncontrolled hydrolysis of 4 and 5. Its molecule is a heptanuclear metal oxoalkoxide of a new type containing a metal core consisting of tetrahedra [Ta 4] with a common vertex. In the mass spectra of 1–3 and 5, along with the ions obtained on fragmentation of Ta(OR) 5, fragments of Ta 20(OR) 8 (R = Me, Et, Bu, Pr') molecules were recorded, the latter are formed as a result of elimination of R 2O from Ta(OR) 5.

5-Phenyl-1,3,4-thiadiazole and 5-phenyl-1,2,4-triazoline-3-thione as products of dehydrogenation of cyclic tautomeric forms of benzaldehyde thiosemicarbazone

5-Pkenyl-1,3,4-thiadiazole and 5-phenyl-1,4-triazoline-3-thione are produced from heterocyclic tautomeric forms of benzaldehyde thiosemicarbazone in the gas phase under conditions existing in a mass spectrometer, and also in the solid phase in the course of thermolysis.

Structure of cobalt hydroxoaluminate and catalytic properties of the products of its reduction

The structure of synthesized cobalt hydroxoaluminate (CHA) and course of thermolysis and reduction were investigated by XPA (including high-temperature x-ray diffraction), thermal chromatography, DTA, DTG, IR, and UV spectroscopy. It was shown that the activity the products of reduction activation of CHA in synthesis of hydrocarbons from CO and H2 is a function of the temperature of reduction and synthesis. It was concluded that hydrocarbons are synthesized on Co/CoAl2O4. The production of CHA are active in the same reduction temperature range as the previously studied cobalt cement catalysts.

Thermal degradation of glycosides, II. Thermal effect on acetates of typical triterpenoid and steroid glycosides

AbstractThe termal effect on acetates of triterpenoid and steroid glycosides was examined. Contrary to the case of free glycosides, on heating the acetates of typical triterpenoid and steroid glycosides (including cardiac glycosides) on a melting point apparatus the cleavage reactions of sugar–aglycone and sugar–sugar linkage did not take place, and no aglycones or prosapogenins were obtained. However, two interesting and useful reactions did occur in the course of thermolysis of cardiac glycoside acetates. By taking into account the thermal effect on the glycoside acetates, and their FD mass spectra, an important suggestion on the mechanism of FD mass fragmentation of the glycosidic linkage was obtained.

Azides. Part V. A kinetic study of the formation of N-(p-toluenesulphonyl)-1H-azepine by thermolysis of p-toluenesulphonylazide in benzene under nitrogen pressure

The course of thermolysis of p-toluenesulphonylazide (A) in benzene at 160 °C and 40.1 atm of nitrogen pressure was followed by analysis of the reactants and products in the reaction mixture by hplc. The rate measurements indicate that the reaction follows first-order kinetics with respect to the formation of N-(p-toluenesulphonyl)-1H-azepine (B) and p-toluencsulphonamide (D). The concentration–time profile is consistent with the formation of p-toluenesulphonylanilide (C) from the azepine (B). The rate constants indicate that the azepine (B) decomposes to the anilide (C) at the same rate at which it is formed.

Non-isothermal differential thermal analysis in the study of the initial state of the thermal decomposition of polynitroaromatic compounds in the condensed state

The activation energies, E, of the decomposition of picramide and its N-methyl-, N-ethyl-, N-n-propyl- and N-n-butyl-derivatives are determined by means of non-isothermal DTA, in its simple form, as well as by the Piloyan method. A relationship is found between the E values of the above-mentioned compounds and the published values of the moments of inertia of the corresponding n-alkyl groups. Taking into account data published previously, which were obtained by application of the Piloyan method in the DTA of polynitroaromates, it is concluded that by suitable selection of DTA measurement conditions, it is possible to record the early part of the exothermal decomposition of the above-mentioned compounds were no autocatalytic influence exists. Attention is also paid to the thermostability of the polynitroaromates due to their contact with the construction materials employed in the course of thermolysis.

Synthesis, Reactions and Catalytic Properties of Stable Alkoxocopper, Phenoxocopper and Related Copper Complexes Containing Triphenylphosphine Ligands

Abstract A variety of new alkoxocopper and phenoxocopper(I) complexes containing triphenylphosphine ligands have been prepared by the reactions of methylbis(triphenylphosphine)copper(I) etherate (I) with the corresponding alcohols and phenols. The isolated complexes were characterized by elemental analysis, IR and NMR spectroscopy and chemical reactions. The reactions of the alkoxocopper and phenoxocopper complexes with alkyl halides and acyl halides or carboxylic anhydrides yield ethers and carboxylic esters, respectively. The stoichiometric exchange reactions of the alkoxo group in the alkoxocopper complexes with carboxylic esters proceed smoothly and the alkoxocopper complexes were found to act as excellent catalysts for the transesterifications between carboxylic esters and alcohols. The exchange reactions take place also between the alkoxocopper complexes and phenols or thiols producing phenoxocopper or alkylthiocopper complexes with the liberation of alcohols. Amides and nitromethane react with the alkoxocopper complexes releasing alcohols to give N-bonded amidocopper and O-bonded acinitrocopper complexes, respectively. The thermolysis of the alkoxocopper complexes in various solvents were studied and the mechanism and the factors influencing the course of thermolysis discussed.