Thermal decomposition of 1-substitutedC-iodotetrazoles in melt and solutions has been investigated. Thermal stabilities, kinetic and activation parameters, and compositions of products of thermolysis ofC-iodotetrazolcs depend on the substituent nature. The scheme of thermolysis ofC-iodotetrazoles has been suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 68–71, January, 1996. 相似文献
The iron(II) complex of the Schiff bases trans-N,N'-bis(salicylidene)-1,2-cyclohexanediamine (Salcn), manganese(II) and vanadyl complexes of the Schiff bases cis- andtrans-N,N'-bis(salicylidene)-1,2-cyclohexanediamine (Salcn) were prepared and characterized by IR spectroscopy, and elemental analysis.
These new complexes were submitted to thermal analysis (TG and DSC) under dynamic air atmosphere. The differences in the decomposition
profiles were related to the structure of isomers and decomposition intermediates were characterized according to their X-ray
diffraction pattern and by their infrared spectrum.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
Conclusions The contribution of the heterogeneous reaction to the rate of the gas phase decomposition of nitroethane, 1-nitropropane, and 2-nitropropane was determined by varying the ratio of the surface to the volume of the reaction vessel (S/V).The activation energies of the homogeneous decomposition of the enumerated compounds differ from the literature data.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1412–1416, July, 1971. 相似文献
The thermal decomposition of azoethane (AE) was studied by detailed product analysis in the temperature and pressure intervals 508–598 K and 2.7–13.3 kPa. Besides the hydrocarbon products, three characteristic and quantitatively important nitrogen-containing compounds were also determined: ethyl-2-butyldiimide, ethanal-diethylhydrazone, and tetraethyl-hydrazine. Apart from the predominant termination reactions of the ethyl radical with itself and with the μ2 radical, the decomposition is characterized by a very short chain reaction. The measurements led to determination of the following rate constants and rate constant ratios: for the following reactions: 相似文献
Journal of Thermal Analysis and Calorimetry - Cellulose has been pyrolysed in nitrogen at two heating rates, and the rates of formation of total gases, and the oxides of carbon, have been measured.... 相似文献
The volative products of thermal decomposition of deuterofullerite C60D19 were studied by mass spectrometry. It was found that D2, CD4, and C6D6 molecules are present in the gas phase above deuterofullerite heated to 773 K. Deuterocarbons appear in the gas phase already at 673 K. 相似文献
The thermal decompositions of dicitratoborates M1[B(C6H6O7)2]·nH2O (n=0–2, M1=Rb, K, Li, NH4) and M11[B(C6H6O7)2]2·8H2O (M11=Co, Ni, Mn, Cu, Zn, Cd) were investigated by means of TG, DTA and DTG methods. It was found that these thermal decompositions involve three successive stages: dehydration, the endothermal decomposition of the ligand, and oxidation of the residual organic component. The volatile products of decomposition in each stage were detected by means of gas chromatography. The method of TG-curve transformation into the curvedm/d T vs.m, wherem is the loss of weight at each moment of time, was used for a more detailed study of dehydration. The optimal conditions for TG-curve modification were found.
Zusammenfassung Die thermische Zersetzung von Dicitratboraten der allgemeinen Formeln M1[B(C6H6O7)2]·nH2O (n=0–2;M1=Rb, K, Li, NH4) und M11[B(C6H6O7)2]2·8H2O (M11=Co, Ni, Mn, Cu, Zn, Cd) wurden mittels TG, DTA und DTG untersucht. Es wurde gefunden, daß die thermische Zersetzung dieser Verbindungen in drei Schritten verläuft: Dehydratisierung, endotherme Zersetzung des Liganden und Oxydation des organischen Rückstandes. Die flüchtigen Zersetzungsprodukte eines jeden Stadiums wurden gaschromatographisch detektiert. Zur detailierten Untersuchung der Dehydratisierung wurden die TG-Kurven zu Kurven transformiert, in denendm/dT gegenm dargestellt ist, wobeim der Gewichtsverlust zu einer gegebenen Zeit ist. Die optimalen Bedingungen für die TG-Kurvenmodifikation wurden festgestellt.
Non isothermal decomposition of synthetically prepared hydromagnesite phase with two different morphologies (2-D micro sheets
and nests) was studied in dynamic nitrogen atmosphere by thermogravimetric analysis, differential thermogravimetric analysis,
and differential scanning calorimetric techniques. Two different kinetic models, i.e. the Friedman isoconversion and the Flynn–Wall
methods were employed for the analysis of thermal decomposition. The apparent activation energy (Ea) of the hydromagnesite phases having 2-D micro sheet and nest morphology were calculated and compared. The activation energy
of nest morphology was found to be relatively higher than 2-D micro sheets. The higher activation energy for the relatively
close packed ‘nest’ morphology is attributed to the difficulty of thermal transport in the core. 相似文献
Thermal decomposition of natural pyrite (cubic, FeS2) has been investigated using X-ray diffraction and57Fe Mössbauer spectroscopy. X-ray diffraction analysis of pyrite ore from different sources showed the presence of associated minerals, such as quartz, szomolnokite, stilbite or stellerite, micas and hematite. Hematite, maghemite and pyrrhotite were detected as thermal decomposition products of natural pyrite. The phase composition of the thermal decomposition products depends on the temperature, time of heating and starting size of pyrite crystals. Hematite is the end product of the thermal decomposition of natural pyrite. 相似文献
The thermal decomposition of dicyanofuroxane (DCFO) proceeds through cleavage of the O-N(O) and C-C bonds of the furoxane ring with formation of dicyanogen N-oxide. The autocatalytic reactions of this N-oxide with DCFO lead to a pentamer, most likely, with 1,2,4-oxadiazole structure.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1916–1918, August, 1991. 相似文献
The thermal decomposition of benzotrifuroxane proceeds through cleavage of the C-C and O-N(O) bonds of the furoxane ring with formation of dinitriloxodifuroxanyl.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1914–1915, August, 1991. 相似文献
The mineral stichtite was synthesised and its thermal decomposition measured using thermogravimetry coupled to an evolved
gas mass spectrometer. Mass loss steps were observed at 52, 294, 550 and 670°C attributed to dehydration, dehydroxylation
and loss of carbonate. The loss of carbonate occurred at higher temperatures than dehydroxylation. 相似文献
The decomposition of C2H6 in Ar was studied by laser-absorption and laser-schlieren measurements of the reaction rate behind incident shock waves with 1300 < T < 2500°K and 1.1 < ρ < 4.4 × 10?6 mol/cm3. The experimental profiles were parameterized by suitable measures of reaction progress. Computer simulations using a 14-reaction mechanism were used to compare assumptions about rate constant expressions with the experimental parameters and to investigate the sensitivity of computed parameters to these assumptions. A rate constant expression k(cm3/mol˙sec) = 2 × 10111T?25.26 exp(?80 320/T) was found for the primary dissociation step C2H6 + M ? CH3 + CH3 + M under the conditions studied; no difference in rate was discernable between M ? Ar and M ? C2H6. Rate constant expressions found to be suitable for the remaining reactions of the mechanism, to some of which the computed parameters were sensitive, were in accord with previous proposals. Our results and results from earlier investigations of the primary decomposition reaction, in both forward and reverse directions, were extrapolated, using RRK methods, to obtain low-pressure limiting rate constants and found to be concordant. 相似文献
The thermal stability of polypyrrole
(PPy) samples has been studied by thermogravimetry/mass spectrometry and pyrolysis-gas
chromatography/mass spectrometry in inert atmospheres. PPy has been prepared
by chemical oxidative polymerization using ferric sulfate as an oxidant and
anionic surfactants, such as dodecylbenzenesulfonic acid and sodium dodecylbenzenesulfonate
as co-dopants. For comparison we have studied polypyrrole (PPy-SO4)
prepared without any additive. It was found that the presence of anionic surfactants
improved the thermal stability of PPy. The decomposition of PPy doped with
ferric sulfate and anionic surfactants occurs at relatively high temperature
indicating that chemical interactions exist between the polymer and the surfactants. 相似文献
The thermal decomposition of theophylline, theobromine, caffeine, diprophylline and aminophylline were evaluated by calorimetrical,
thermoanalytical and computational methods. Calorimetrical studies have been performed with aid of a heat flux Mettler Toledo
DSC system. 10 mg samples were encapsulated in a 40 μL flat-bottomed aluminium pans. Measurements in the temperature range
form 20 to 400°C were carried out at a heating rate of 10 and 20°C min−1 under an air stream. It has been established that the values of melting points, heat of transitions and enthalpy for methylxanthines
under study varied with the increasing of heating rate.
Thermoanalytical studies have been followed by using of a derivatograph. 50, 100 and 200 mg samples of the studied compounds
were heated in a static air atmosphere at a heating rate of 3, 5, 10 and 15°C min−1 up to the final temperature of 800°C. By DTA, TG and DTG methods the influence of heating rate and sample size on thermal
destruction of the studied methylxanthines has been determined. For chemometric evaluation of thermoanalytical results the
principal component analysis (PCA) was applied. This method revealed that first of all the heating rate influences on the
results of thermal decomposition. The most advantageous results can be obtained taking into account sample masses and heating
rates located in the central part of the two-dimensional PCA graph. As a result, similar data could be obtained for 100 mg
samples heated at 10°C·min−1 and for 200 mg samples heated at 5°C min−1. 相似文献
Struvite (NH4MgPO4·6H2O) is a mineral often found in urinary tracts and kidneys. Thermal decomposition using slow low heating shows that the 'kidney'
stone can be decomposed at temperatures below 40°C. At this temperature both ammonia and water are evolved. If more rapid
heating is employed the decomposition occurs at around 80°C. The implication of this work rests with the use of low slow heat
for the decomposition of the kidney stones.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
The thermal decomposition of ulexite, NaCa[B5O6(OH)6] · 5H2O, monocrystals was investigated by thermal, X-ray, IR and optical microscopy methods at normal and elevated temperatures.It was found that the thermal decomposition has an intraframework character and proceeds in a few separate stages: 1) release of part of the molecular water coordinating the Ca and Na cations; this leads to a rearrangement of the ulexite structure; 2) release of the remaining molecular water and some part the OH groups, which causes breakdown of the ulexite structure, with the simultaneous crystallization of CaO · B2O3 and 2CaO·B2O3; 3) the slow release of the remaining OH groups up to 600°C, which causes decomposition of the borate rings and the crystallization of NaB3O5 and NaCaBO3.
Zusammenfassung Mittels thermischer, röntgenographischer, IR- und optisch mikroskopischer Verfahren wurde bei Normal- und bei hohen Temperaturen die thermische Zersetzung von Ulexiteinkristallen NaCa[BsO6(OH)6]·5H2O untersucht.Die Untersuchungen zeigten, daß die thermische Zersetzung von Ulexit einen Innergittercharakter trägt und in einigen separaten Schritten verläuft: 1) Freisetzung desjenigen molekularen Wassers, welches Ca und Na Kationen koordiniert; hierdurch geschieht eine Wiederherstellung der Ulexit-struktur, 2) Freisetzung des verbleibenden Kristallwassers und einem Teil der OH-Gruppen, wodurch eine Zersetzung der Ulexit-struktur unter gleichzeitiger Kristallisation von CaO · B2O3 und 2CaO · B2O3 erfolgt, 3) langsame Freisetzung der verbleibenden OH-Gruppen bis 600°C, was eine Spaltung der Boratringe und die Kristallisation von NaB3O5 und NaCaBO3 zur Folge hat.