The thermal decomposition of alkaline earth formates

The thermal decomposition of alkaline earth formates has been studied. Experiments with single crystals, compacts and powders of strontium formate demonstrate that the method of sample presentation can affect the rate of decomposition.For anhydrous calcuim, strontium and barium formates, isothermal kinetic runs show that the decompositions follow the Erofeev law, In(l-α) = ktⁿ; the measured activation energies were 199.4, 228 and 270 kJ/mol respectively.     

The thermal decomposition of alkali metal formates

The thermal decompositions of lithium, sodium, potassium, rubidium and caesium formates were investigated by a complex dynamic thermoanalytical method. The ratio of the products in reactions resulting in alkali metal carbonates and oxalates depended variously on the atmosphere used. Differences were found compared to isothermal investigations, in that the catalytic effects of bases could not be observed and the oxalate-conversion was lower. The formation of oxalate did not occur in the cases of lithium and caesium formates; the order for the other salts was sodium formate < potassium formate > rubidium formate.     

Composition of the thiophene-group component of the gaseous products of the thermal decomposition of Kashpir shales

Summary It was shown that the main bulk of the light fraction of the thiophenes-aromatics part of Kashpir shale-gas gasoline consists of the following a romatic hydrocarbons and thiophene compounds; benzene, toluene, m-xylene, thiophene, 2 methylthiophene 2.5-dimethylthiophene, and 2-ethyl-5-methylthiophene.     

The thermal decomposition of metal formates. II. Solid state thermal decomposition studies on magnesium formate dihydrate

Magnesium formate dihydrate has been synthesized by the action of formic acid on anhydrous magnesium oxide. This product analysed as Mg(COOH)₂ · 2H₂O. Its mode of thermal decomposition has been studied by thermal methods of analysis including simultaneous DTA/mass spectrometry. Nitrogen adsorption surface area of the solid products at various stages of its decomposition have been obtained. X-Ray diffraction and scanning electron micrographs have also been used to interpret the results. The decomposition of magnesium formate took place in three stages, which includes a phase change, at 265°C. The endotherm at 430°C changed to an exotherm in the presence of air; it corresponded to the decomposition of a new anhydrous phase of magnesium formate. The effect of the sample holder and changing atmospheres on the DSC analysis has been investigated. A scheme is presented for the thermal decomposition.     

Effect of fluorine-containing nano-sized multi-functional additives on thermal decomposition behavior and gaseous products of double-base propellants

Journal of Thermal Analysis and Calorimetry - To study the effect of fluorine-containing nano-sized multi-functional additives on the thermal decomposition behavior and gaseous products of...     

Influence of the cation on the formation of free hydrogen and formaldehyde in the thermal decomposition of formates

Three stages have been distinguished in the thermal decomposition of formates: It was found that in the first stage carbon dioxide is evolved, leaving structural elements of the respective cation hydride in the reaction system: \(HCO_2^ - \to H^ - + CO_2 \) The second stage depends on the character of the bond in the intermediately formed hydride: The third stage is connected with formaldehyde transformation into different organic compounds, depending on the character of the metal oxide formed in the thermal decomposition of the formate. This explains the formation of free hydrogen and organic compounds identified as thermal decomposition products of various formates.     

The thermal decomposition of the carbonate reaction products

The complex thermal analysis was used in the investigations of the carbonate reaction products in the residue after Al leaching from calcium aluminate-12CaO·7Al₂O₃ and Selfdisintegrated Powder. The conversion of Al was calculated basing on a content of Al in the pregnant solution as well as in a residue obtained from the kinetic investigations. The third method of measurements of a conversion of Al was presented and discussed. Results show, that the proposed method can be used for conversion estimations with 95% of confidence level as well as for the detection of carbonate products and is useful for an interpretation of the new approach for kinetic mechanism of Al leaching.     

Synthesis of germanium sols via thermal decomposition of gaseous germane

A new approach to the synthesis of colloidal Ge nanoparticles in high-boiling solvent via thermal decomposition of germane is presented. Obtained products were analyzed by XRD, XRF, TEM, absorption spectrophotometry, Raman IR and PL spectroscopy. Ge nanoparticles have mean sizes about 4–5 nm, are apparently amorphous and nonspherical.     

Determination of gaseous products of thermal degradation of thiram

Journal of Thermal Analysis and Calorimetry - Thiram is one of the commonly used carbamate pesticides. Unfortunately, the thermal degradation and combustion of that substance can lead to emission...     

Radical products of thermal decomposition of polydiphenylenesulfophthalide

The investigation of the vacuum thermal decomposition of polydiphenylenesulfophthalide at 100–530 °C showed that there are at least four main types of paramagnetic species (PMSs). The ESR spectrum of type I PMSs (120–250 °C) has a signal (g = 2.0028; ΔH ～1 mT) with a poorly resolved hyperfine structure (HFS) and an even number of lines. The electronic spectrum of these particles shows an absorption band at ～410 nm. These particles were assigned to “low-temperature” triarylmethyl-type radicals (TAMTR), which are apparently generated from dioxothioxanthene defect structures of the polymer. Type II PMSs (250–360 °C) give a smooth symmetrical ESR singlet (g = 2.0028; ΔH ～1 mT) and two absorption bands in the electronic spectrum at ～410 nm (strong band) and ～710 nm (weak band). Based on the results of calculations of electronic spectra for a series of model structures at the TD-DFT B3LYP/6-311G(d,p) level of theory, these PMSs were assigned to “high-temperature” TAMTR, which have a fluorenyl structure and are formed through the opening of the sulfophthalide ring. The maximum concentration of TAMTR II (～10²⁰ spin g^?1) is achieved at 320 °C. At T > 320 °C, type II radicals decay and type III radicals are generated. The latter are condensed aromatic species presumably having a phenalene structure. In the temperature range of 350–450 °C, the ESR line width and shape remain mainly unchanged, which attests to the retention of the dominant structure of the radicals. An increase in the thermal decomposition temperature to ～450 °C or above leads to a decrease in the ESR line width and a change in its shape from the Gaussian to Lorentzian type. This fact is an evidence of type IV paramagnetic species corresponding to even higher condensed aromatic structures.     

Radical products of the thermal decomposition of ionol hydroperoxide

It has been shown that the thermal decomposition of 4-hydroperoxy-4-methyl-2, 6-ditert-butylcyclohexadien-2, 5-one is accompanied by the rupture of the C-O bond in the COOH group, with the formation of 2, 6-ditert-butyl-4-methylphenoxyl radicals. On the basis of the electronic paramagnetic resonance spectra, it has been found that transfer of hydrogen occurs from the diphenylamine molecule and those of sterically hindered phenols to the radicals of 2, 6-ditert-butyl-4-methylphenoxyl radicals formed by the decomposition of the hydroperoxide.     

A spin-trap ESR study of the decomposition of alkyl formates

Conclusions By using nitroso compound ESR spin traps it has been shown that the alkyl formates break down into radicals under irradiation at 2537 Å and 25°C, and this regardless of whether or not the system contains added tert-butyl peroxide. The mechanism of breakdown varies with the alkyl-formate structure, Under our conditions of irradiation, the product radicals were as follows: OOCH₃ from methyl formate; OOCH₂CH₃ and HCOOHCH₃ from ethyl formate; OOC(CH₃)₃ and (CH₃)₃ from tert-butyl formate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 542–545, March, 1977.     

The products of the thermal decomposition of CH3CHO

We have used a heated 2 cm × 1 mm SiC microtubular (μtubular) reactor to decompose acetaldehyde: CH(3)CHO + Δ → products. Thermal decomposition is followed at pressures of 75-150 Torr and at temperatures up to 1675 K, conditions that correspond to residence times of roughly 50-100 μs in the μtubular reactor. The acetaldehyde decomposition products are identified by two independent techniques: vacuum ultraviolet photoionization mass spectroscopy (PIMS) and infrared (IR) absorption spectroscopy after isolation in a cryogenic matrix. Besides CH(3)CHO, we have studied three isotopologues, CH(3)CDO, CD(3)CHO, and CD(3)CDO. We have identified the thermal decomposition products CH(3) (PIMS), CO (IR, PIMS), H (PIMS), H(2) (PIMS), CH(2)CO (IR, PIMS), CH(2)=CHOH (IR, PIMS), H(2)O (IR, PIMS), and HC≡CH (IR, PIMS). Plausible evidence has been found to support the idea that there are at least three different thermal decomposition pathways for CH(3)CHO; namely, radical decomposition: CH(3)CHO + Δ → CH(3) + [HCO] → CH(3) + H + CO; elimination: CH(3)CHO + Δ → H(2) + CH(2)=C=O; isomerization∕elimination: CH(3)CHO + Δ → [CH(2)=CH-OH] → HC≡CH + H(2)O. An interesting result is that both PIMS and IR spectroscopy show compelling evidence for the participation of vinylidene, CH(2)=C:, as an intermediate in the decomposition of vinyl alcohol: CH(2)=CH-OH + Δ → [CH(2)=C:] + H(2)O → HC≡CH + H(2)O.     

Study of the radical products of the thermal decomposition of nitrocellulose

The thermal transformations of nitrocellulose are accompanied by the formation of RN0₂ ^– radicals and allyl radicals. A mechanism for the formation of these radicals was proposed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2641–2644, November, 1989.     

Influence of the nature of organic components in dinuclear copper(II) pivalates on the composition of thermal decomposition products

Tetrabridged dinuclear complexes ((2-NH₂)C₅H₄N)₂Cu₂(μ₂-OOCCMe₃)₄ (2·С₆Н₆) and ((3-NH₂)C₅H₄N)₂Cu₂(μ₂-OOCCMe₃)₄ (3) and the cocrystallization product ((4-NMe₂)C₅H₄N)₂Cu(η²–OOCCMe₃)₂·2((4-NMe₂)C₅H₄N)₂Cu₂(μ₂-OOCCMe₃)₄ (4) were synthesized by the reaction of the polymer [Cu(OOCCMe₃)₂]_n (1) with aminopyridine ligands (L) of different nature (Cu: L = 1:1) in С₆Н₆. The solid-state thermal decomposition of these compounds was studied by differential scanning calorimetry and thermogravimetry, and their electrochemical behavior was investigated by cyclic voltammetry. All newly synthesized complexes were studied by X-ray diffraction, the magnetic properties of the complexes were investigated, and ESR measurements were performed.     

Molecular structures of mononitroanilines and their thermal decomposition products

The molecular structures of 2-nitro, 3-nitro, and 4-nitroaniline and their internal rotational isomers were calculated by anab-initio method using HF/6-31G* basis set. The geometries were influenced by the nitro group's position. The perturbation of the amino group on the nitro group was observed in a 2-nitroaniline isomer having a molecular structure distinct from that of the other two isomers. Among them, 4-nitroaniline is the most stable one. Internal rotation tests of either the nitro or amino group of 3-nitro and 4-nitroaniline indicate that no significant deformations of the phenyl ring occurred after internal rotation; however, the internal rotational isomers of 2-nitroaniline differed from its original structure. Relatively easier internal rotation of the nitro group than the amino group and different C-NO₂ and C-NH₂ bonds indicate the bond-breaking message of nitroanilines. As products of explosives induced by thermal or shock are of interest, five products of 2-nitroaniline were selected to assess their geometries and energies. The above calculations revealed that these products are thermodynamically unfavorable.     

The combustion—coulometric determination of sulphur in gaseous and liquid organic products

A combustion—coulometric procedure is described for the determination of sulphur in gaseous and liquid organic materials with a final boiling point below 550°C. Modifications to the original Dohrmann procedure concerning combustion, titration and removal of interfering compounds have resulted in a more stable and sensitive system capable of detecting 0.15 ng of sulphur. Concentrations of sulphur down to 0.03 mg kg^-1 can be determined within a few minutes.     

Kinetics of the thermal decomposition of α-polynitroalkyl sulfides and α-polynitroalkyl sulfones in the gaseous phase

Conclusions A study has been made of the gas-phase decomposition of eight-polynitroalkyl Sulfides and-polynitroalkyl sulfones. Decomposition parameters have been estimated and a mechanism involving rupture of the C-NO₂ bond has been established. Substitution of a S atom in the position to the NO₂ group lowers the C-NO₂ bond energy by R10 kcal/mole.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 310–312, February, 1977.