The thermal and initiated thermal decomposition of biacetyl-d6

The thermal and methyl radical initiated decomposition of biacetyl-d₆ were investigated at conversions 5% over the temperature range of 387-412°C and 251–292°C, respectively. The deuterated sample contained 10.5% biacetyl-d₅. The reaction products were analyzed by mass spectrometry. The following data could be determined from product ratios: where E is in kcal/mol With reasonable assumptions and literature data Arrhenius parameters for elementary steps were derived and discussed in particular with respect to isotopic effects in H/D-abstraction reactions.     

Synthesis and thermal decomposition of haloalkoxy-sym-triazines

Reaction of [2-methylthio-6-dialkylamino-sym-triazin-4-yl]trimethylammonium chlorides with ethylene chlorohydrin gave 2-methylthio-4-(2-chloroethoxy)-6-dialkylamino-sym-triazines, which are converted to 2-methylthio-3-(2-chloroethyl)-4-oxo-6-dialkylamino-3,4-dihydro-symtriazines when they are heated to 115–120°C and to the corresponding tetrahydrothiazolo-symtriazine derivatives when they are heated at 180–190°C.See [1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1420–1423, October, 1977.     

Synthesis and thermal decomposition of haloalkoxy-sym-triazines

The reaction of 4,6-bis[alkyl(dialkyl)amino]- or (4-alkylamino-6-dialkylamino-sym-triazin-2-yl)trimethylammonium chlorides with ethylene chlorohydrin and the action of phosphorus pentachloride on 2--hydroxyethoxy-sym-triazines give 2--chloroethoxy derivatives of sym-triazine, which on heating are converted to imidazo[1,2-a]-sym-triazine derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 262–265, February, 1977.     

Preparation and thermal decomposition of halogenometallates

Five new derivatives of general formula [Ru(dipy)₃]MCl₄, whereM=Cu(II), Zn(II), Mn(II), Fe(II) and Co(II), and [Ru(dipy)₃][FeCl₄]₂ were synthesized, and their compositions and structures were confirmed by chemical analysis and electron absorptionüspectroscopy. The thermal decompositions of the compounds were studied by thermoanalytical methods. All these complexes decompose upon heating up to 1300 K, with simultaneous loss of organic fragments and structures were confirmed by chemical analysis and electron absorption spectroscopy.The exothermic effects. The residues after heating correspond to RuO₂ and the appropriate M oxides, contaminated in some cases by pure metal.

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Zusammenfassung Fünf neue Komplexverbindungen des Typs [Ru(dipy)₃](MCl₄] (dipy=2,2-Dipyridyl;M=Cu, Zn, Mn, Fe, Co) sowie [Ru(dipy₃](FeCl₄]₂ wurden dargestellt und ihre Zusammensetzung und Struktur durch chemische Analyse und Elektronenspektroskopie bestätigt. Ihre thermische Zersetzung wurde durch simultane TG-DTA untersucht. Alle Komplexverbindungen zersetzen sich beim Erhitzen bis auf 1300 K unter gleichzeitigem Verlust der organischen Komponente und des Cl an die Gasphase. Der thermische Abbau ist von starken exothermen Effekten begleitet. Die Rückstände nach dem Erhitzen enthalten RuO₂ und das jeweilige Metalloxid, in einigen Fällen durch Metall verunreinigt.

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[Ru(dipy)₃]MCl₄, M = , , , , [Ru(dipy)₃][FeCl₄]₂. , . 1300 . . , .

     

Synthesis of CeO2 by thermal decomposition of oxalate and kinetics of thermal decomposition of precursor

CeO₂ was synthesized by calcining Ce₂(C₂O₄)₃·8H₂O above 673 K in air. The precursor and its calcined products were characterized using thermogravimetry and differential scanning calorimetry, Fourier transform infrared spectra, X-ray powder diffraction, scanning electron microscopy, and UV–Vis absorption spectroscopy. The result showed that cubic CeO₂ was obtained when the precursor was calcined above 673 K in air for 2 h. The UV–Vis absorption spectroscopy studies showed that superfine CeO₂ behaved as an excellent UV-shielding material. The thermal decomposition of the precursor in air experienced two steps, which are: first, the dehydration of eight crystal water molecules, then the decomposition of Ce₂(C₂O₄)₃ into cubic CeO₂. The values of the activation energies associated with the thermal decomposition of Ce₂(C₂O₄)₃·8H₂O were determined based on the Starink equation.     

The thermal decomposition of water

The reflected shock tube technique with multipass absorption spectrometric detection of OH‐radicals at 308 nm, corresponding to a total path length of 1.749 m, has been used to study the reaction H₂O + M → H + OH + M between 2196 and 2792 K using 0.3, 0.5, and 1% H₂O, diluted in Kr. As a result of the increased sensitivity for OH‐radical detection, the existing database for this reaction could be extended downward by ～500 K. Combining the present work with that of Homer and Hurle, the composite rate expression for water dissociation in either Ar or Kr bath gas is k_{1,Ar(or Kr)} = (2.43 ± 0.57) × 10^?10 exp(?47117 ± 633 K/T) cm³ molecule^?1 s^?1 over the T‐range of 2196–3290 K. Applying the Troe factorization method to data for both forward and reverse reactions, the rate behavior could be expressed to within <±18% over the T‐range, 300–3400 K, by the three‐parameter expression k_1,Ar = 1.007 × 10⁴ T^?3.322 exp(?60782 K/T) cm³ molecule^?1 s^?1 A large enhancement due to H₂O with H₂O collisional activation has been noted previously, and both absolute and relative data have been considered allowing us to suggest k₁, H₂ O = 1.671 × 10² T^?2.440 exp(?60475 K/T) cm³ molecule^?1 s^?1 for the rate constants with H₂O bath gas over the T‐range, 300–3400 K. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 211–219, 2006     

The thermal decomposition of biacetyl

The thermal decomposition of biacetyl has been studied at small percentage conversion over the temperature range 375-417°C. For these conditions, an almost quantitative mass balance was obtained by gas-chromatographic analysis. The following equation was obtained for the overall reaction Between 240° and 277°C, the decomposition of biacetyl initiated by methyl radicals has also been studied. As source of radicals, the thermolysis of azomethane was used. Moreover, the Arrhenius parameters of the following reactions were determined: where A is in sec^?1 for reaction (1) and in cm³mole^?1 sec^?1 for reactions (3) and (4); E is in kcal/mole. Evidence is provided that the displacement reaction (4) proceeds by a two step mechanism.     

The thermal decomposition of vermiculite

Vermiculite shows some promising potentials, both as ion-exchange material and thermal insulation. The thermal decomposition of vermiculite from Sokli, Finland, has been studied by various thermoanalytical methods, including high-temperature X-ray diffraction and high-pressure DTA. The major phases occurring during successive heating are: 15Å → 11.8Å → 10.1Å → 9.74Å → 9.3Å (all d₀₀₂ spacings). Reaction enthalpies and activation energies are given for most of the reactions. For the evaluation of kinetic parameters, high-temperature X-ray diffraction is suggested as a powerful tool, superior to most conventional methods.     

The thermal decomposition of n-hexane

The kinetics of the pyrolysis of n-hexane was studied in a conventional static reactor over a temperature range of 650–840 K. The overall reaction is essentially first order with the kinetic parameters A = 10^13.92 s^?1 and E_A = 260.3 kJ/mol. The distributions of the main products were analyzed by gas chromatography. A reaction model involving 240 elementary reactions was developed to describe the experimental rate data. The agreement of the model with experimental data was surprisingly good over a wide range of temperatures and pressures and up to medium extents of conversion. Methods for sensitivity studies based upon the quasi-stationary-state assumption (QSSA) were developed, and for a number of more detailed effects, such as self-inhibition, explanations could be given. It was also shown that the hexyl isomerization reactions influence strongly the product distribution. The outstanding capability of kinetic modeling with computer simulations in handling complex kinetic systems is demonstrated.     

The thermal decomposition of chlorodifluoromethane

The kinetics of pyrolysis of chlorodifluoromethane have been studied in a flow system between 670° and 750° using partial press of CF₂HCl between 17 mm and 200 mm Hg. The reaction obeys first order kinetics at low conversions, but is retarded by hydrogen chloride. The major features of the reaction are explained by the following mechanism:     

Preparation and thermal decomposition of indium hydroxide

Summary Indium hydroxides were prepared by the mixing of aqueous indium nitrate solution with sodium or ammonium hydroxide solutions under various conditions. The thermal decomposition of the resulting materials was examined by thermogravimetry, differential thermal analysis, X-ray diffraction study and infrared spectroscopy. It has been found that sodium hydroxide solution is more suitable than the addition of ammonium hydroxide solution to prepare indium hydroxide in well crystallization; the thermal decomposition of indium hydroxide, in which the composition is In(OH)₃·xH₂O where x￡2, proceeds according to the following process: In(OH)₃·xH₂O?cubic In(OH)₃?cubic In₂O₃     

Thermal stability and thermal decomposition of N-oxides

Kinetic manometric studies indicate that the first step in the thermal decomposition of a number of N-oxides is the formation of a cyclic activated complex. There is a correlation between the thermal stability of the compounds studied in the liquid phase and the charge on the oxygen atom of the N-oxide group calculated by the MPDP method. Autocatalysis of gas evolution from halogenopyridine N-oxides is explained by hydrogen halide autocatalysis. The limit of thermal stability for N-oxides is likely to be no greater than 270°C.Biisk Lyceum, Altai Region, Biisk 659302. Kazan' State Technological University, Kazan' 420015. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1573–1576, November, 1995. Original article submitted October 20, 1995.     

Synthesis and thermal decomposition of cobalt-containing oligosilanes

Oligo(phenylcobaltcarbonylsilane) was prepared from oligo(phenylsilane) and dicobalt octacarbonyl. The reaction proceeds with elimination of H₂ and CO and insertion of cobalt carbonyl fragments into the silicone backbone of oligosilane. Oligosilane containing cobalt carbonyl groups in side organic substituents was obtained from oligolmethyl(phenylethynyl)Isilane and CO₂(CO)₈. The reaction of 1,2-bis(phenylethyny1)tetramethyldisilane with Co₂(CO)₈ proceeds with the sequential attachment of cobalt carbonyl fragments to ethynyl groups to form disilane derivatives [²-CCPhCo₂(CO)₆] Thermal decomposition of cobalt-containing oligosilanes affords a mixture of paramagnets and ferromagnets.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 10, pp. 2561–2567, October, 1996.     

Structure and thermal decomposition of ammonium metatungstate

The structure and morphology of ammonium metatungstate (AMT), (NH₄)₆[H₂W₁₂O₄₀]?4H₂O, and its thermal decomposition in air and nitrogen atmospheres were investigated by SEM, FTIR, XRD, and TG/DTA-MS. The cell parameters of the AMT sample were determined and refined with a full profile fit. The thermal decomposition of AMT involved several steps in inert atmosphere: (i) release of crystal water between 25 and 200 °C resulting in dehydrated AMT, (ii) formation of an amorphous phase between 200 and 380 °C, (iii) from which hexagonal WO₃ formed between 380 and 500 °C, and (iv) which then transformed into the more stable m-WO₃ between 500 and 600 °C. As a difference in air, the as-formed NH₃ ignited with an exothermic heat effect, and nitrous oxides formed as combustion products. The thermal behavior of AMT was similar to ammonium paratungstate (APT), (NH₄)₁₀[H₂W₁₂O₄₂]?4H₂O, the only main difference being the lack of dry NH₃ evolution between 170 and 240 °C in the case of AMT.     

Kinetics of thermal decomposition of dinitramide

Kinetic regularities of thermal decomposition of dinitramide in aqueous and sulfuric acid solutions were studied in a wide temperature range. The rate of the thermal decomposition of dinitramide was established to be determined by the rates of decomposition of different forms of dinitramide as the acidity of the medium increases: first, N(NO₂)⁻ anions, then HN(NO₂)₂ molecules, and finally, protonated H₂N(NO₂)₂ ⁺ cations. The temperature dependences of the rate constants of the decomposition of N(NO₂)⁻ (k _an) and HN(NO₂)₂ (k′_ac) and the equilibrium constant of dissociation of HN(NO₂)₂ (K _a) were determined:k _an=1.7·10¹⁷ exp(−20.5·10³/T), s⁻¹,k′_ac=7.9·10¹⁶ exp(−16.1·10³/T), s⁻¹, andK _a=1.4·10 exp(−2.6·10³/T). The temperature dependences of the decomposition rate constant of H₂N(NO₂)₂ ⁺ (k _d) and the equilibrium constant of the dissociation of H₂N(NO₂)₂ ⁺ (K _d) were estimated:k _d=10¹² exp(−7.9·10³/T), s⁻¹ andK _d=1.1 exp(6.4·10³/T). The kinetic and thermodynamic constants obtained make it possible to calculate the decomposition rate of dinitramide solutions in a wide range of temperatures and acidities of the medium. In this series of articles, we report the results of studies of the thermal decomposition of dinitramide performed in 1974–1978 and not published previously. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2129–2133, December, 1997.     

Mechanism of thermal decomposition of hydrogenphosphities

Evolution of hydrogen during thermal decomposition of some M^IIHPO₃ (M= Mg, Ca, Zn, Sr, Cd, Ba) phosphities under nitrogen atmosphere was investigated. Step mechanism of thermal decomposition has been proposed.

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Zusammenfassung Es wurde die Wasserstoffentwicklung während der thermischen Zersetzung einiger Phosphite M^II)HPO₃ (mitM=Mg, Ca, Zn, Sr, Cd, Ba) in einer Stickstoffatmosphäre untersucht. Es wurde ein schematischer Mechanismus für die thermische Zersetzungsreaktion gegeben.

     

Kinetics of thermal decomposition of hexanitrohexaazaisowurtzitane

Thermal decomposition of hexanitrohexaazaisowurtzitane (HNIW) in the solid state and in solution was studied by thermogravimetry, manometry, optical microscopy, and IR spectroscopy. The kinetics of the reaction in the solid state is described by the first-order equation of autocatalysis. The rate constants and activation parameters of HNIW thermal decomposition in the solid state and solution were determined. The content of N₂ amounts to approximately half of the gaseous products of HNIW thermolysis. The thermolysis of HNIW and its burning are accompanied by the formation of a condensed residue. During these processes, five of six nitro groups of the HNIW molecule are removed, and one NO₂ group remains in the residue, which contains amino groups and no C−H bonds. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 815–821, May, 2000.