Non-isothermal Decomposition Kinetics of K(AHDNE)

The thermal behavior and non-isothermal decomposition kinetics of 1-amino-1-hydrazino-2,2-dinitro- ethylene potassium salt[K(AHDNE)] were studied under the non-isothermal conditions by different scanning calorimeter(DSC) method. The thermal behavior of K(AHDNE) presents three exothermic decomposition processes. The kinetic equation of the first thermal decomposition reaction obtained is dα/dT=(10^19.63/β)3(1-α)[-ln(1-α)]^2/3exp(-1.862× 10⁵/RT). The self-accelerating decomposition temperature(T_SADT) and critical temperature of thermal explosion(T_b) of K(AHDNE) are 162.5 and 171.4 ℃, respectively. K(AHDNE) has higher thermal stability than AHDNE.     

1-氨基-1-肼基-2,2-二硝基乙烯（AHDNE）的非等温分解动力学，比热容和绝热至爆时间研究

利用DSC和TG/DTG法研究了1-氨基-1-肼基-2,2-二硝基乙烯（AHDNE）热分解行为及分解动力学,第一热分解过程的动力学方程为： ,其热爆炸临界温度为98.16 ºC。同时,利用微量热法测定了AHDNE的比热容,298.15K时的标准摩尔比热容为211.86 J•mol-1•K-1。计算得到了AHDNE的绝热至爆时间为59.21 s。AHDNE是不稳定的,其热稳定性远低于母体化合物FOX-7。     

Structural Characterization and Thermal Properties of 1-Amino-1-ethylamino-2,2-dinitroethylene

1-amino-1-ethylamino-2,2-dinitroethylene (AEFOX-7) was synthesized by the reaction of 1,1-diamino-2,2-dinitroethylene (FOX-7) and ethylamine aqueous solution at 92 oC. The the-oretical investigation on AEFOX-7 was carried out by B3LYP/6-311++G^**method. The IR frequencies and NMR chemical shifts were performed and compared with the experi-mental results. The thermal behavior of AEFOX-7 was studied with differential scanning calorimetry and thermal gravity-derivative thermogravimetry methods, and can be divided into a melting process and an exothermic decomposition process. The enthalpy, apparent activation energy and pre-exponential factor of the exothermic decomposition reaction were obtained as 374.88 kJ/mol, 169.7 kJ/mol, and 10^19.24 s^-1, respectively. The critical temper-ature of thermal explosion of AEFOX-7 is 145.2 oC. The specific heat capacity of AEFOX-7 was determined with micro-DSC method and theoretical calculation method, and the molar heat capacity is 214.50 J/(mol K) at 298.15 K. The adiabatic time-to-explosion of AEFOX-7 was calculated to be a certain value between 1.38-1.40 s. The thermal stability of AEFOX-7 is much lower than that of FOX-7.     

Thermal Behavior of 2‐(Dinitromethylene)‐1,3‐diazacyclopentane

A new compound, 2‐(dinitromethylene)‐1,3‐diazacyclopentane (DNDZ), was prepared by the reaction of 1,1‐diamino‐2,2‐dinitroethylene (FOX‐7) with 1,2‐diaminoethane in N‐methylpyrrolidone (NMP). Thermal decomposition of DNDZ was studied under non‐isothermal conditions by DSC, TG/DTG methods, and the enthalpy, apparent activation energy and pre‐exponential factor of the exothermic decomposition reaction were obtained as 317.13 kJ·mol^?1, 269.7 kJ·mol^?1 and 10^24.51 s^?1, respectively. The critical temperature of thermal explosion was 261.04°C. Specific heat capacity of DNDZ was determined with a micro‐DSC method and a theoretical calculation method, and the molar heat capacity was 205.41 J·mol^?1·K^?1 at 298.15 K. Adiabatic time‐to‐explosion was calculated to be a certain value between 263–289 s. DNDZ has higher thermal stability than FOX‐7.     

Studies on an ionic compound (3-ATz)+ (NTO)–: crystal structure, specific heat capacity, thermal behaviors and thermal safety

A new ionic compound (3-ATz)⁺ (NTO)^?C was synthesized by the reaction of 3-amino-1,2,4-triazole (3-ATz) with 3-nitro-1,2,4-triazol-5-one (NTO) in ethanol. The single crystals suitable for X-ray diffraction measurement were obtained by crystallization at room temperature. The crystal is monoclinic, space group p _2(1)/c with crystal parameters of a?=?0.6519(2)?nm, b?=?1.9075(7)?nm, c?=?0.6766(2)?nm, ???=?94.236(4)°, R ₁?=?0.0305 and wR ₂?=?0.0789. The thermal behaviors were studied, and the apparent activation energy and pre-exponential constant of the exothermic decomposition stage were obtained by Kissinger??s method and Ozawa??s method. The self-accelerating decomposition temperature is 505.40?K, and the critical temperature of the thermal explosion is obtained as 524.90?K. The specific heat capacity was determined with Micro-DSC method and the theoretical calculation method, and the standard molar specific heat capacity is 221.31?J?mol^?1?K^?1 at 298.15?K. The Gibbs free energy of activation, enthalpy of activation, and entropy of activation are 151.55?kJ?mol^?1, 214.52?kJ?mol^?1 and 122.44?J?mol^?1?K^?1. The adiabatic time-to-explosion of the compound was estimated to be a certain value between 5.0 and 5.2?s, and the detonation velocity (D) and pressure (P) were also estimated using the nitrogen equivalent equation according to the experimental density.     

Synthesis and properties of an energetic complex pentaamminecobalt (III) perchlorate,with 4-amino-1,2,4-triazole as ligand

Energetic metal complex, 4-amino-1,2,4-triazole-N¹(N²) pentaamminecobalt(III) perchlorate, was produced by the anation reaction of aqua pentaamminecobalt(III) perchlorate with 4-amino-1,2,4-triazole. The thermal decomposition of the metal complex and its mixtures with 1,1-diamino-2,2-dinitroethylene (FOX-7) was studied.     

Low-temperature heat capacity of L- and DL-phenylglycines

Heat capacity of crystalline L- and DL-phenylglycines was measured in the temperature range from 6 to 305?K. For L-phenylglycine, no anomalies in the C _p (T) dependence were observed. For DL-phenylglycine, however, an anomaly in the temperature range 50?C75?K with a maximum at about 60?K was registered. The enthalpy and the entropy changes corresponding to this anomaly were estimated as 20?J?mol^?1 and 0.33?J?K^?1 mol^?1, respectively. In the temperature range 205?C225?K, an unusually large dispersion of the experimental points and a small change in the slope of the C _p (T) curve were noticed. Thermodynamic functions for L- and DL-phenylglycines in the temperature range 0?C305?K were calculated. At 298.15?K, the values of heat capacity, entropy, and enthalpy are equal to 179.1, 195.3?J?K^?1 mol^?1, and 28590?J?mol^?1 for L-phenylglycine and 177.7, 196.3?J?K^?1 mol^?1 and 28570?J?mol^?1 for DL-phenylglycine. For both L- and DL-phenylglycine, the C _p (T) at very low temperatures does not follow the Debye law C ?C T ³ . The heat capacity C _p (T) is slightly higher for L-phenylglycine, than for the racemic DL-crystal, with the exception of the phase transition region. The difference is smaller than was observed previously for the L-/DL-cysteines, and considerably smaller, than that for L-/DL- serines.     

The influence of reagents solvation on enthalpy change of glycine-ion protonation and silver(I) glycine-ion complexation in aqueous-dimethylsulfoxide solutions

The thermal decomposition process and non-isothermal decomposition kinetic of glyphosate were studied by the Differential thermal analysis (DTA) and Thermogravimetric analysis (TGA). The results showed that the thermal decomposition temperature of glyphosate was above 198?°C. And the decomposition process was divided into three stages: The zero stage is the decomposition of impurities, and the mass loss in the first and second stage may be methylene and carbonyl, respectively. The mechanism function and kinetic parameters of non-isothermal decomposition of glyphosate were obtained from the analysis of DTA?CTG curves by the methods of Kissinger, Flynn?CWall?COzawa, Distributed activation energy model, Doyle and ?atava-?esták, respectively. In the first stage, the kinetic equation of glyphosate decomposition obtained showed that the decomposition reaction is a Valensi equation of which is two-dimensional diffusion, 2D. Its activation energy and pre-exponential factor were obtained to be 201.10?kJ?mol^?1 and 1.15?×?10¹⁹?s^?1, respectively. In the second stage, the kinetic equation of glyphosate decomposition obtained showed that the decomposition reaction is a Avrami?CErofeev equation of which is nucleation and growth, and whose reaction order (n) is 4. Its activation energy and pre-exponential factor were obtained to be 251.11?kJ?mol^?1 and 1.48?×?10²¹?s^?1, respectively. Moreover, the results of thermodynamical analysis showed that enthalpy change of ??H ^??, entropy change of ??S ^?? and the change of Gibbs free energy of ??G ^?? were, respectively, 196.80?kJ?mol^?1,107.03?J?mol^?1?K^?1, and 141.77?kJ?mol^?1 in the first stage of the process of thermal decomposition; and 246.26?kJ?mol^?1,146.43?J?mol^?1?K^?1, and 160.82?kJ?mol^?1 in the second stage.     

Thermal decomposition and non-isothermal decomposition kinetics of carbamazepine

The thermal stability and kinetics of isothermal decomposition of carbamazepine were studied under isothermal conditions by thermogravimetry (TGA) and differential scanning calorimetry (DSC) at three heating rates. Particularly, transformation of crystal forms occurs at 153.75°C. The activation energy of this thermal decomposition process was calculated from the analysis of TG curves by Flynn-Wall-Ozawa, Doyle, distributed activation energy model, ?atava-?esták and Kissinger methods. There were two different stages of thermal decomposition process. For the first stage, E and logA [s^?1] were determined to be 42.51 kJ mol^?1 and 3.45, respectively. In the second stage, E and logA [s^?1] were 47.75 kJ mol^?1 and 3.80. The mechanism of thermal decomposition was Avrami-Erofeev (the reaction order, n = 1/3), with integral form G(α) = [?ln(1 ? α)]^1/3 (α = ～0.1–0.8) in the first stage and Avrami-Erofeev (the reaction order, n = 1) with integral form G(α) = ?ln(1 ? α) (α = ～0.9–0.99) in the second stage. Moreover, ΔH ^≠, ΔS ^≠, ΔG ^≠ values were 37.84 kJ mol^?1, ?192.41 J mol^?1 K^?1, 146.32 kJ mol^?1 and 42.68 kJ mol^?1, ?186.41 J mol^?1 K^?1, 156.26 kJ mol^?1 for the first and second stage, respectively.     

Non-isothermal decomposition kinetics of diosgenin

The thermal stability and kinetics of isothermal decomposition of diosgenin were studied by thermogravimetry (TG) and Differential Scanning Calorimeter (DSC). The activation energy of the thermal decomposition process was determined from the analysis of TG curves by the methods of Flynn-Wall-Ozawa, Doyle, ?atava-?esták and Kissinger, respectively. The mechanism of thermal decomposition was determined to be Avrami-Erofeev equation (n = 1/3, n is the reaction order) with integral form G(α) = [?ln(1 ? α)]^1/3 (α = 0.10–0.80). E _a and logA [s^?1] were determined to be 44.10 kJ mol^?1 and 3.12, respectively. Moreover, the thermodynamics properties of ΔH ^≠, ΔS ^≠, and ΔG ^≠ of this reaction were 38.18 kJ mol^?1, ?199.76 J mol^?1 K^?1, and 164.36 kJ mol^?1 in the stage of thermal decomposition.     

Cesium chromate,Cs2CrO4: heat capacity and thermodynamic properties from 5 to 350 K

The heat capacity of a sample of Cs₂CrO₄ was determined in the temperature range 5 to 350 K by aneroid adiabatic calorimetry. The heat capacity at constant pressure C_p^o(298.15 K), the entropy S^o(298.15 K), the enthalpy {H^o(298.15 K) - H^o(0)} and the function $\text{? {G}{}^{\mathrm{o}}\text{(298.15}\text{K}\text{) - H}{}^{\mathrm{o}}\text{(0)}}\text{298.15}\text{K}$ were found to be (146.06 ± 0.15) J K^?1 mol^?1, (228.59 ± 0.23) J K^?1 mol^?1, (30161 ± 30) J mol^?1, and (127.43 ± 0.13) J K^?1 mol^?1, respectively. The heat capacity C_p^o(298.15 K) and entropy S^o(298.15 K) and entropy S^o(298.15 K) of Rb₂CrO₄ are estimated to be (146.0 ± 1.0) J K^?1 mol^?1 and (217.6 ± 3.0) J K^?1 mol^?1, respectively.     

Kinetics of non-isothermal decomposition of cinnamic acid

The thermal stability and kinetics of decomposition of cinnamic acid were investigated by thermogravimetry and differential scanning calorimetry at four heating rates. The activation energies of this process were calculated from analysis of TG curves by methods of Flynn-Wall-Ozawa, Doyle, Distributed Activation Energy Model, ?atava-?esták and Kissinger, respectively. There are only one stage of thermal decomposition process in TG and two endothermic peaks in DSC. For this decomposition process of cinnamic acid, E and logA[s^?1] were determined to be 81.74 kJ mol^?1 and 8.67, respectively. The mechanism was Mampel Power law (the reaction order, n = 1), with integral form G(α) = α (α = 0.1–0.9). Moreover, thermodynamic properties of ΔH ^≠, ΔS ^≠, ΔG ^≠ were 77.96 kJ mol^?1, ?90.71 J mol^?1 K^?1, 119.41 kJ mol^?1.     

Thermochemical investigation of natural antlerite

Thermal and thermochemical investigations of natural hydroxyl-bearing copper sulfate Cu₃SO₄(OH)₄??antlerite have been carried out. The stages of its thermal decomposition have been studied employing the Fourier-transform IR spectroscopy. The enthalpy of formation of antlerite from the elements ??_f H _m ^o (298.15?K)?=?(?1750?±?10)?kJ?mol^?1 has been determined by the method of oxide melt solution calorimetry. Using value of S _m ^o (298.15?K), equal to (263.46?±?0.47)?J?K^?1?mol^?1, obtained earlier by the method of adiabatic calorimetry, the Gibbs energy value of ??_f G _m ^o (298.15?K)?=?(?1467?±?10)?kJ?mol^?1 has been calculated.     

Low-temperature heat capacity and standard enthalpy of formation of neodymium glycine perchlorate complex [Nd2(Gly)6(H2O)4](ClO4)6·5H2O

Rare-earth perchlorate complex coordinated with glycine [Nd₂(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O was synthesized and its structure was characterized by using thermogravimetric analysis (TG), differential thermal analysis (DTA), chemical analysis and elementary analysis. Its purity was 99.90%. Heat capacity measurement was carried out with a high-precision fully-automatic adiabatic calorimeter over the temperature range from 78 to 369 K. A solid-solid phase transformation peak was observed at 256.97 K, with the enthalpy and entropy of the phase transformation process are 4.438 kJ mol⁻¹ and 17.270 J K⁻¹ mol⁻¹, respectively. There is a big dehydrated peak appears at 330 K, its decomposition temperature, decomposition enthalpy and entropy are 320.606 K, 41.364 kJ mol⁻¹ and 129.018 J K⁻¹ mol⁻¹, respectively. The polynomial equations of heat capacity of this compound in different temperature ranges have been fitted. The standard enthalpy of formation was determined to be −8023.002 kJ mol⁻¹ with isoperibol reaction calorimeter at 298.15 K.     

Reaction paths of BCl3?+?CH4?+?H2 in the chemical vapor deposition process

The reaction paths in the chemical vapor deposition preparation of boron carbides with BCl₃?CCH₄?CH₂ precursors were investigated theoretically in detail with a total number of 82 intermediates (IM) and 118 transition states (TS). The geometries of the species were optimized with B3PW91/6-311G(d,p) method and the TS as well as their linked IM were confirmed with the frequency and the intrinsic reaction coordinates analyses at the same theoretical level. The energy barriers and the reaction energies were determined with the accurate model chemistry method G3(MP2) after a diagnosis of the non-dynamic electronic correlations. The heat capacities and entropies were obtained with statistical thermodynamics. The Gibbs free energies at 298.15?K for all of the reaction steps were reported and the data at any temperature can be developed with the classical thermodynamics by using the fitted (as a function of temperature) heat capacities. All the possible elementary reactions, including both direct decomposition and the radical attacking dissociations for each reaction step were examined. It was found that there are nine reaction steps in the lowest reaction pathway to produce the final boron carbide and five steps to produce boron. The highest energy barrier in the lowest reaction pathway is 238.6?kJ?mol^?1 at 298.15?K and 346.0?kJ?mol^?1 at 1,200?K for producing BC, and is 294.7?kJ?mol^?1 at 298.15?K and 314.2?kJ?mol^?1 at 1,200?K for producing B.     

Preparation and characterization of nitrogen-rich bis-1-methylimidazole1H,1′H-5,5′-bistetrazole-1,1′-diolate energetic salt

A new nitrogen-rich energetic salt of bis-1-methylimidazole 1H,1′H-5,5′-bistetrazole-1,1′-diolate salt, (1-M)₂BTO, was synthesized and characterized (FT-IR, ¹H NMR, ¹³C NMR, elemental analysis, and X-ray single-crystal diffraction). Results indicated that (1-M)₂BTO crystallizes in the triclinic space group P-1. The thermal decomposition behavior of (1-M)₂BTO was determined by differential scanning calorimetry (DSC) and thermogravimetric tandem infrared spectroscopy. The decomposition peak temperature of (1-M)₂BTO was 530 K, which suggested that the salt is strong heat resistance. The apparent activation energies were 130.56 kJ mol^?1 (Kissinger’s method) and 132.50 kJ mol^?1 (Ozawa’s method), respectively. The enthalpy of formation for the salt was calculated as 917.3 kJ mol^?1. The detonation velocity and detonation pressure of (1-M)₂BTO were 7448 m s^?1 and 20.7 GPa, respectively, using the Kamlet-Jacobs equation. Furthermore, the sensitivity test results showed that its impact sensitivity is greater than 50 J and friction sensitivity is 180 N, indicating that it has a lower sensitivity.

     

Non-isothermal Decomposition Kinetics, Specific Heat Capac-ity and Adiabatic Time-to-explosion of a High Energy Material: 4,6-Bis(5-amino-3-nitro-1,2,4-triazol-1-yl)-5-nitropyrimidine

The thermal behavior of 4,6‐bis‐(5‐amino‐3‐nitro‐1,2,4‐triazol‐1‐yl)‐5‐nitropyrimidine (BANTNP) was studied under a non‐isothermal condition by DSC, PDSC and TG/DTG methods. The kinetic parameters (E_a and A) of the exothermic decomposition reaction are 304.52 kJ·mol^?1 and 10^24.47 s^?1 at 0.1 MPa, 272.52 kJ·mol^?1 and 10^21.76 s^?1 at 5.0 MPa, respectively. The kinetic equation at 0.1 MPa can be expressed as: dα/dT=10^25.3(1?α)^3/4exp(?3.8044×10⁴/T)/β The critical temperature of thermal explosion is 588.28 K. The specific heat capacity of BANTNP was determined with a Micro‐DSC method, and the standard molar specific heat capacity is 397.54 J·mol^?1·K^?1 at 298.15 K. The adiabatic time‐to‐explosion of BANTNP was calculated to be 11.75 s.     

Equilibrium sublimation and thermodynamic properties of SnSe and SnSe2

Knudsen effusion studies of the sublimation of polycrystalline SnSe and SnSe₂, prepared by annealing and chemical vapor transport reactions, respectively, have been carried out using vacuum microbalance techniques in the temperature ranges 736–967 K and 608–760 K, respectively. From experimental mass-loss data for the sublimation reaction SnSe(s) = SnSe(g), the recommended values for the heat of formation and absolute entropy of SnSe(s) were calculated to be ΔH°_298,f = ?86.4 ± 9.9 kJ · mol^?1 and S°₂₉₈ = 89.0 ± 7.1 J · K^?1 · mol^?1. From mass-loss data for the decomposition reaction \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm SnSe}_{\rm 2} ({\rm s)} = {\rm SnSe(s)} + \frac{1}{{\rm x}}{\rm Se}_{\rm x} ({\rm g) (x} = 2 - 8) $\end{document}, the recommended values for the heat of formation and absolute entropy of SnSe₂(s) were determined to be ΔH°_298,f = ?118.1 ± 15.1 kJ · mol^?1 and S°₂₉₈ = 111.8 ± 11.8 J · K^?1 mol^?1.     

Hermetic thermal behaviors and specific heat capacities of bis(aminofurazano)furazan and bis(nitrofurazano)furazan

Thermal behaviors of bis(aminofurazano)furazan (BAFF) and bis(nitrofurazano)furazan (BNFF) were studied by the differential scanning calorimetry (DSC) method with a special hermetic high-pressure crucible and compared to that with a common standard Al crucible. The exothermic decomposition processes of the two compounds were completely revealed. The extrapolated onset temperature, peak temperature and enthalpy of exothermic decomposition at the heating rate of 10 °C min^?1 are 290.2, 313.4 °C and ??2174 J g^?1 for BAFF, and 265.8, 305.0 °C and ??2351 J g^?1 for BNFF, respectively. The apparent activation energies of the decomposition process for the two compounds are 115.7 and 131.7 kJ mol^?1, respectively. The self-accelerating decomposition temperatures and critical temperatures of thermal explosion are 247.5 and 368.7 °C for BAFF, and 249.6 and 268.1 °C for BAFF, respectively. Both BAFF and BNFF present high thermal stability. The specific heat capacities for the two compounds were determined with the micro-DSC method, and the specific heat capacities and molar heat capacities at 298.15 K are 1.0921 J g^?1 K^?1 and 257.9 J mol^?1 K^?1 for BAFF, and 1.0419 J g^?1 K^?1 and 308.5 J mol^?1 K^?1 for BNFF, respectively.     

Thermochemical properties for n‐propyl,iso‐propyl,and tert‐butyl nitroalkanes,alkyl nitrites,and their carbon‐centered radicals

Density functional theory (DFT) based calculations are performed on a series of alkyl nitrites and nitroalkanes representing large‐scale primary, secondary, and tertiary nitro compounds and their radicals resulting from the loss of their skeletal hydrogen atoms. Geometries, vibration frequencies, and thermochemical properties [S°(T) and C°_p(T) (10 K ? T ? 5000 K)] are calculated at the B3LYP/6‐31G(d,p) DFT level. Δ_fH°₂₉₈ values are from B3LYP/6‐31G(d,p), B3LYP/6‐31+G(2d,2p), and the composite CBS‐QB3 levels. Potential energy barriers for the internal rotations have been computed at the B3LYP/6‐31G(d,p) level of theory, and the lower barrier contributions are incorporated into entropy and heat capacity data. The standard enthalpies of formation at 298 K are evaluated using isodesmic reaction schemes with several work reactions for each species. Recommended values derived from the most stable conformers of respective nitro‐ and nitrite isomers include ?30.57 and ?28.44 kcal mol^?1 for n‐propane‐, ?33.89 and ?32.32 kcal mol^?1 for iso‐propane‐, ?42.78 and ?41.36 kcal mol^?1 for tert‐butane‐nitro compounds and nitrites, respectively. Entropy and heat capacity values are also reported for the lower homologues: nitromethane, nitroethane, and corresponding nitrites. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 181–199, 2010