Thermal Decomposition (thermal + decomposition)

Distribution by Scientific Domains
Distribution within Chemistry

Terms modified by Thermal Decomposition

  • thermal decomposition kinetics
  • thermal decomposition temperature

  • Selected Abstracts


    Mixed-Anion and Mixed-Cation Borohydride KZn(BH4)Cl2: Synthesis, Structure and Thermal Decomposition

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2010
    Dorthe B. Ravnsbk
    Abstract KZn(BH4)Cl2, synthesized for the first time, contains a heteroleptic complex anion [Zn(BH4)Cl2],, extending the structural diversity of metal borohydrides. In-situ synchrotron powder diffraction, NMR and Raman spectroscopy were used to characterize KZn(BH4)Cl2 and to evaluate the mechanism for its thermal decomposition. The title compound decomposes at a significantly lower temperature than KBH4 and may be used for inspiration for the design of novel hydrogen storage materials. Combining different ligands in modified metal borohydrides is proposed as a way to adjust stability with respect to hydrogen desorption. [source]


    Syntheses and Characterization of Lead(II) N,N -Bis[1(2)H -tetrazol-5-yl]amine Compounds and Effects on Thermal Decomposition of Ammonium Perchlorate

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2009
    Weitao Wang
    Abstract Three new lead(II) N,N -bis[1(2)H -tetrazol-5-yl]amine (H2bta) compounds, [Pb(bta)(H2O)2]n (1), [Pb2(bta)2(bpy)2] (2), and [Pb2(bta)2(phen)2]2H2O (3), were synthesized. Single-crystal X-ray diffraction reveals that compound 1 has a 1D polymeric zigzag chain structure, whereas compounds 2 and 3 have binuclear structures. In addition, compounds 1,3 were explored as additives to promote the thermal decomposition of ammonium perchlorate by differential scanning calorimetry. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


    Facile Synthesis of Bastnaesite -Type LaF[CO3] and Its Thermal Decomposition to LaOF for Bulk and Eu3+ -Doped Samples

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2009
    Oliver Janka
    Abstract Rare-earth metal(III) oxide fluorides with the composition MOF (M = La,Lu) seem to offer promising host lattices for luminescence applications by doping these materials with trivalent lanthanoid cations. Unfortunately, there was no simple and practicable way to synthesize the compounds in phase-pure quality with classical solid-state chemistry reactions. However, by using the rare-earth metal(III) fluoride oxocarbonates, MF[CO3], as solution-born precursor materials that crystallize with a bastnaesite -type structure, easy access is now possible by mild thermal decomposition. Synthetic details, investigations on the phase purity and the presence of the oxocarbonate anion [CO3]2, proved by IR measurements as well as from X-ray powder diffraction data are given in this paper for the example of bulk LaF[CO3] and Eu3+ -doped samples. The latter (LaF[CO3]:Eu3+) shows a bright orange-red luminescence that is stronger than that of the product of its thermal decomposition: trimorphic LaOF:Eu3+.( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


    Nanocomposite Formation Through Thermal Decomposition of Mixed Samarium and Magnesium Citrate-Derived Gels Formed by Spray Pyrolysis

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2008
    Thorsten Enz
    Metal citrate gels of samarium and magnesium were used as precursors for the generation of hollow sphere particles by spray pyrolysis under mild thermal conditions. Six mixtures with different Sm/Mg ratios as well as pure Sm and Mg samples were prepared. As a result of the low synthesis temperature the particles consist of amorphous metal carboxylate networks. The texture of the shells is governed by microporosity yielding the major part of the total surface area. A detailed investigation of thermal decomposition, crystallization, and grain growth behavior was carried out under constant heating rate conditions. The decomposition products are nanocrystalline Sm2O3 and MgO and corresponding two-phase nanocomposites. The pure samarium carboxylate gel features considerably higher thermal stability compared with the one comprised of only magnesium. Accordingly the decomposition behavior of mixed samples is dependent on the Sm/Mg ratio. Furthermore it is shown that small amounts of MgO are able to slow down the kinetics of grain growth of Sm2O3 whereas high amounts are necessary to significantly reduce the final grain size at 1000C. [source]


    Novel Phosphorus-Containing Poly(ether sulfone)s and Their Blends with an Epoxy Resin: Thermal Decomposition and Fire Retardancy

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2006
    Ulrike Braun
    Abstract Summary: The decomposition of novel phosphorus-containing poly(oxyphenylene-sulfonyl-phenylene-oxy-diphenyl phenylene phosphine oxide) (PSU_I), 2,5-dihydroxy-1-biphenylene-phosphine oxide based polysulfone (PSU_II), poly(sulfonyl-diphenylphenylene phosphonate) (PSU_P) and bisphenol A-based polysulfone (PSU) is studied. The influence of the chemical structure, charring and phosphorus release is discussed based on the mass loss, kinetics and products. The pyrolysis and fire behaviour of blends with epoxy resin (EP) are studied. For EP-PSU_II, phosphorus initiates water elimination and changes the decomposition pathway of EP. The fire behaviour of EP-PSU shows some improvements, whereas the heat release rate is crucially reduced for EP-PSU_II due to simultaneous char formation and flame inhibition. Decomposition model of PSU_II. [source]


    An Investigation on Thermal Decomposition of DNTF-CMDB Propellants

    PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2007
    Wei Zheng
    Abstract The thermal decomposition of DNTF-CMDB propellants was investigated by pressure differential scanning calorimetry (PDSC) and thermogravimetry (TG). The results show that there is only one decomposition peak on DSC curves, because the decomposition peak of DNTF cannot be separated from that of the NC/NG binder. The decomposition of DNTF can be obviously accelerated by the decomposition products of the NC/NG binder. The kinetic parameters of thermal decompositions for four DNTF-CMDB propellants at 6,MPa were obtained by the Kissinger method. It is found that the reaction rate decreases with increasing content of DNTF. [source]


    Thermal Decomposition of NTO: An Explanation of the High Activation Energy

    PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 4 2007
    Valery
    Abstract Burning rate characteristics of the low-sensitivity explosive 5-nitro-1,2,4-triazol-3-one (NTO) have been investigated in the pressure interval of 0.1,40,MPa. The temperature distribution in the combustion wave of NTO has been measured at pressures of 0.4,2.1,MPa. Based on burning rate and thermocouple measurements, rate constants of NTO decomposition in the molten layer at 370,425,C have been derived from a condensed-phase combustion model (k=8.08,1013,exp(,19420/T) s,1. NTO vapor pressure above the liquid (ln P=,9914.4/T+14.82) and solid phases (ln P=,12984.4/T+20.48) has been calculated. Decomposition rates of NTO at low temperatures have been defined more exactly and it has been shown that in the interval of 180,230,C the decomposition of solid NTO is described by the following expression: k=2.9,1012,exp(,20680/T). Taking into account the vapor pressure data obtained, the decomposition of NTO in the gas phase at 240,250,C has been studied. Decomposition rate constants in the gaseous phase have been found to be comparable with rate constants in the solid state. Therefore, a partial decomposition in the gas cannot substantially increase the total rate. High values of the activation energy for solid-state decomposition of NTO are not likely to be connected with a sub-melting effect, because decomposition occurs at temperatures well below the melting point. It has been suggested that the abnormally high activation energy in the interval of 230,270,C is a consequence of peculiarities of the NTO transitional process rather than strong bonds in the molecule. In this area, the NTO molecule undergoes isomerization into the aci -form, followed by C3-N2 heterocyclic bond rupture. Both processes depend on temperature, resulting in an abnormally high value of the observed activation energy. [source]


    Synthesis, Thermal Decomposition and Sensitivity Study of CsDNBF

    PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2007
    Shaozong Wang
    Abstract CsDNBF (cesium 7-hydroxy-4,6-dinitro-5,7-dihydrobenzofuroxanide) was synthesized from the sodium salt of DNBF and cesium nitrate. The thermal decomposition process has been investigated and the results show that the solid residues at 240,C are RCOOCs, CsNCO, RNO2 and CsNO3. The sensitivity results demonstrate that CsDNBF has better properties than KDNBF, which has been widely used. [source]


    Thermal Decomposition of Energetic Materials 84: Pyrolysis of 5-Substituted 1,3,5-Trinitrohexahydropyrimidines

    PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2003
    Brian
    Abstract Results of slow and fast pyrolysis were compared for 1,3,5-trinitrohexahydropyrimidine compounds in which the 5-position was substituted by H, CH3, NO2, CH2ONO2, and CH2N3. IR and Raman spectroscopy were used to identify and quantify all of the gaseous products. The decomposition process appears to be initiated by reactions at the 5-position of the ring. The gases produced are rather similar for all of the compounds, however the different functional groups impart their own signature on the concentrations of several products. [source]


    Thermal Decomposition of Energetic Materials 85: Cryogels of Nanoscale Hydrazinium Diperchlorate in Resorcinol-Formaldehyde

    PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2003
    Bryce
    Abstract The objective of this work was to try to desensitize an energetic material by using sol-gel processing and freeze drying to incorporate the energetic material into the fuel matrix on the nano (or at least submicron) particle size scale. Hydrazinium diperchlorate ([N2H6][ClO4]2 or HP2) and resorcinol-formaldehyde (RF) were chosen as the oxidizer and fuel, respectively. Solid loading up to 88% HP2 was achieved by using the sol gel-to-cryogel method. Various weight percentages of HP2 in RF were characterized by elemental analysis, scanning electron (SEM) and optical microscopy, T-jump/FTIR spectroscopy, DSC, and drop-weight impact. SEM indicated that 20,50,nm diameter HP2 plates aggregated into porous 400,800,nm size clusters. Below 80% HP2 the cryogels are less sensitive to impact than physical mixtures having the same ratios of HP2 and RF. The decomposition temperatures of the cryogels are higher than that of pure HP2, which is consistent with their lower impact sensitivity. The heat of decomposition as measured at a low heating rate increases with increasing percentage of HP2. The cryogels and physical mixtures release similar amounts of energy, but the cryogels exhibit mainly a single exotherm by DSC whereas the physical mixtures showed a two-step energy release. Flash pyrolysis revealed gaseous product ratios suggestive of more energy being released from the cryogels than the physical mixtures. Cryogels also burn faster by visual observation. [source]


    ChemInform Abstract: Thermal Decomposition of N-Alkylated-2-aminobenzophenones.

    CHEMINFORM, Issue 44 2009
    Evelyn Cuevas Creencia
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


    ChemInform Abstract: An ab initio Study of Possible Pathways in the Thermal Decomposition of NaAlH4

    CHEMINFORM, Issue 9 2009
    J. G. O. Ojwang
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


    ChemInform Abstract: Hexachloroplatinates of the Lanthanides: Syntheses and Thermal Decomposition of [M(NO3)2(H2O)6]2 [PtCl6]2H2O (M: La, Pr) and [M(NO3)(H2O)7] [PtCl6]4H2O (M: Gd, Dy).

    CHEMINFORM, Issue 17 2008
    Annika Arndt
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


    An Investigation of the Nd2O3,MoO3 Phase System: Thermal Decomposition of Nd2Mo4O15 and Formation of Nd6Mo10O39.

    CHEMINFORM, Issue 39 2006
    Rosemary S. Barker
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]


    Thermal Decomposition of Iron(VI) Oxides, K2FeO4 and BaFeO4, in an Inert Atmosphere.

    CHEMINFORM, Issue 32 2006
    Janos Madarasz
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]


    Synthesis and Thermal Decomposition of Ditetrazol-5-ylamine.

    CHEMINFORM, Issue 31 2006
    V. V. Nedel'ko
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]


    ChemInform Abstract: Thermal Decomposition of TeSeO4 and Te3SeO8 , Phase Relations in the Ternary System TeO2/SeO2/Bi2SeO5.

    CHEMINFORM, Issue 44 2001
    P. Schmidt
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


    ChemInform Abstract: Preparation of Nanosized Perovskite-Type LaMnO3 Powders Using the Thermal Decomposition of a Heteronuclear Complex LaMn(dhbaen)(OH)(NO3)(H2O)4.

    CHEMINFORM, Issue 34 2001
    Hiromichi Aono
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


    Cobalt Hydroxide Nanosheets and Their Thermal Decomposition to Cobalt Oxide Nanorings

    CHEMISTRY - AN ASIAN JOURNAL, Issue 4 2008
    Xiaohe Liu Dr.
    Abstract We demonstrate herein that single-crystalline ,-cobalt hydroxide (,-Co(OH)2) nanosheets can be successfully synthesized in large quantities by a facile hydrothermal synthetic method with aqueous cobalt nitrate as the cobalt source and triethylamine as both an alkaline and a complexing reagent. This synthetic method has good prospects for the future large-scale production of single-crystalline ,-Co(OH)2 nanosheets owing to its high yield, low cost, and simple reaction apparatus. Single-crystalline porous nanosheets and nanorings of cobalt oxide (Co3O4) were obtained by a thermal-decomposition method with single-crystalline ,-Co(OH)2 nanosheets as the precursor. A probable mechanism of formation of ,-Co(OH)2 nanosheets, porous Co3O4 nanosheets, and Co3O4 nanorings was proposed on the basis of the experimental results. [source]


    Synthesis, Crystal Structure, Thermal Decomposition and Sensitivity Properties of [Zn(AZT)4(H2O)2](PA)24H2O and [Zn(AZT)2(H2O)4](HTNR)24H2O

    CHINESE JOURNAL OF CHEMISTRY, Issue 11 2008
    Yan CUI
    Two new coordination compounds [Zn(AZT)4(H2O)2](PA)2 4H2O and [Zn(AZT)2(H2O)4]- (HTNR)24H2O have been prepared by using AZT (3-azido- 1,2,4-triazole) as ligands, PA, (picrate) or HTNR, (anion formed by the deprotonation of one of the two hydroxyl-groups of 2,4,6-trinitroresorcinol) as outer anions. The central zinc(II) ion is coordinated by four N atoms of four AZT molecules and two O atoms of two H2O molecules in [Zn(AZT)4(H2O)2](PA)24H2O. In [Zn(AZT)2(H2O)4](HTNR)2 4H2O, six coordination-atoms come from two N atoms of two AZT molecules and four O atoms of four H2O molecules. [source]


    Low-Temperature Heat Capacity and Thermal Decomposition of Crystalline [Ho(Thr)(H2O)5] Cl3

    CHINESE JOURNAL OF CHEMISTRY, Issue 8 2003
    Xiao-Zheng
    First page of article [source]


    Alkali Metal (Li+,Cs+) Salts with Hexafluorochromate(V), Hexafluorochromate(IV), Pentafluorochromate(IV), and Undecafluorodichromate(IV) Anions

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2008
    Zoran Mazej
    Abstract The compounds ACrF6 (A = Li,Cs) were prepared by photochemical reactions of AF/CrF3 mixtures in anhydrous HF with elemental F2 at ambient temperature. The crystal structures of compounds ACrF6 (A = K,Cs) are analogous to that of KOsF6, and NaCrF6 exhibits polymorphism. The trigonal phase (II) can be classified to have the well-known LiSbF6 type of structure, while the crystal structure of the orthorhombic modification (I) appears to be a new structure-type. Thermal decomposition of the ACrF6 salts produce ACrF5(A = Rb, Cs), ACrF5/A2CrF6 (A = K), or A2CrF6 (A = Li, Na). These compounds undergo partial solvolysis in anhydrous HF with precipitation of CrF4. From the remaining solutions of the [CrF6]2, anions and dissolved AF (A = Li,Cs), single crystals of ACrF5 (A = K,Cs), A2CrF62HF (A = Na, K), A2CrF64HF (A = Rb, Cs), Li2CrF6, and K3Cr2F112HF were grown, and their crystal structures determined. The main structural feature of the ACrF5 compounds is the infinite zig-zag [CrF5]nn, chain of distorted [CrF6] octahedra joined by cis vertices. The crystal structures of A2CrF62HF (A = Na, K) and A2CrF64HF (A = Rb, Cs) consist of distorted [CrF6]2, octahedra involved in moderate to strong hydrogen bonding with HF molecules, while two A+ cations compensate the negative charge of each octahedron. In Na2CrF62HF, two neighboring HF molecules are involved in moderate to strong hydrogen bonding with each other. (HF)2 dimers with a parallelogram structure are formed. The mutual interactions in the crystal structure of K2CrF62HF differ from those found in Na2CrF62HF. In the former, each HF molecule interacts with the [CrF6]2, anion and three K+ cations. A2CrF64HF compounds of Rb and Cs are isostructural. Their structures consist of A+ cations and [CrF6]2, anions involved in hydrogen bonding with two sets of HF molecules in the trans position. The crystal structure of K3Cr2F112HF reveals a rare case of the [M2F11]3, anion. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]


    Decomposition Cascades of Dicoordinate Copper(I) Chalcogenides

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 33 2007
    Heiko Jacobsen
    Abstract Cu,E, Si,E, and Cu,P bond energies of R3PCuESiR3 and CuESiR3 complexes (E = O, S, Se) have been investigated using PBE density-functional calculations, and including empirical corrections for dispersive interactions (DFT-D). The bond energies have been used to investigate likely pathways of molecular decomposition. The energy profile for thermal decomposition is to a large degree independent of the nature of the phosphane ligands and silyl groups. Oxides, sulfides, and selenides have qualitatively the same thermal decomposition profile. Thermal decomposition is not likely to produce copper chalcogenide units CuE, but elemental copper Cu instead. Consideration of intermolecular van der Waals attraction suggests that the linear geometry of system tBu3PCuOSiPh3 as found in the crystal is most likely due to crystal packing and intermolecular forces.( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]


    Structural Relationships in High-Nuclearity Heterobimetallic Bismuth-Oxo Clusters

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2005
    Michael Mehring
    Abstract The novel heterobimetallic sodium-bismuth-oxo clusters [Bi2Na4O(OSiMe3)8] (1), [Bi10Na5O7(OH)6(OSiMe3)15]1.5C7H8 (21.5C7H8), [Bi15Na3O18(OSiMe3)12]C7H8 (3C7H8) and [Bi14Na8O18(OSiMe3)14(THF)4]C6H6 (4C6H6) were prepared starting from BiCl3 and NaOSiMe3. Compound 1 crystallises in the trigonal space group Rc with the lattice constants a = 12.8844(3) and c = 54.6565(3) , compound 21.5C7H8 crystallises in the triclinic space group P with the lattice constants a = 15.0377(2) , b = 16.0373(2) , c = 27.8967(5) , , = 87.1321(6), , = 86.6530(7) and , = 63.6617(6), compound 3C7H8 crystallises in the monoclinic space group C2/c with the lattice constants a = 54.311(11), b = 19.846(4), c = 22.885(5) and , = 112.32(3), and compound 4C6H6 crystallises in the trigonal space group R with the lattice constants a = 15.9786(4) and c = 46.8329(17) . The formation of M,O,M bonds results from both partial hydrolysis followed by condensation as well as from elimination of Me3SiOSiMe3 from M,OSiMe3 groups. The hexanuclear metal-oxo silanolate 1 is more conveniently synthesised by the addition of NaOSiMe3 to a toluene solution of in situ-prepared [Bi(OSiMe3)3]. The metal-oxo(hydroxo) silanolates differ significantly in composition, but show similar building units. Thermal decomposition of the metal-oxo silanolates in the solid state gave heterogeneous decomposition products containing bismuth silicates. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]


    Thermal decomposition of cyclic organic peroxides in pure solvents and binary solvent mixtures

    INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 6 2010
    Maringeles Iglesias
    The thermal decomposition reaction of acetone cyclic triperoxide, acetone cyclic diperoxide, 4-heptanone cyclic diperoxide, and pinacolone cyclic diperoxide ca. 0.02 M was studied in pure solvents (acetone and 1-propanol) and in binary mixtures of acetone/1-propanol at 150C. The kinetics of each system was explored by gas chromatography (GC) at different solvent compositions. The reactions showed a behavior accordingly with a pseudo-first-order kinetic law up to at least 90% peroxide decomposition. The main organic products derived from these thermolysis reactions were detected by GC analysis. Among them, the corresponding ketones, methane, ethane, and propane were the main identified products. The rates of decomposition of pinacolone diperoxide in the pure solvents were practically independent of the solvent characteristics, so it was of no interest to analyze its kinetic behavior in binary solvent mixtures. In acetone/1-propanol mixtures, the solvation effect on the cyclic peroxides derived from 4-heptanone and acetone molecules was slightly dominated by specific interactions between 1-propanol and a diradical-activated complex initially formed. This species was preferentially solvated by 1-propanol instead of acetone. Specific interactions between the O atoms from the peroxidic bond and the H from the OH in 1-propanol can be taken into account. 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 347,353, 2010 [source]


    Thermal decomposition of tert -butyl peroxide in a gas chromatographic reactor: A comparison of kinetic approaches

    INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 7 2004
    Peter J. Skrdla
    The thermal decomposition of tert -butyl peroxide is investigated utilizing both the column and the injection port of a commercial gas chromatograph (GC) as chemical reactors. Using the injector liner as the reactor, the chromatographic peak areas of the reactant, measured at various injector temperatures, are used in the determination of the activation energy of the decomposition (Ea). With the column serving as the reactor, both the reactant peak areas and the product peak shapes are similarly utilized for this purpose. Values of Ea obtained using different mathematical treatments for each of the three approaches are found to range from 115 to 164 kJ/mol. Of these methods, the column reactor approach utilizing peak area measurements (referred to as PACR, for "peak area, column reactor") is found to be far superior in terms of its speed, robustness, and its accuracy in determining Ea. The PACR method's effectiveness can be largely attributed to the mathematical treatment that is described in the approach. 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 386,393, 2004 [source]


    Kinetics and thermodynamic parameters of the thermal decomposition of imipramine hydrochloride and trimipramine maleate

    INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 4 2003
    Rafie H. Abu-Eittah
    Thermal decomposition of imipramine hydrochloride and trimipramine maleate has been investigated isothermally and nonisothermally. The kinetic parameters, namely the activation energy Ea and the Arrhenius preexponential term A, were calculated. Applying the theory of activated complex to the process of decomposition one calculated ,S,, ,H,, and ,G, for the reaction. The values of Ea as well as the thermodynamic functions did not vary significantly with temperature of the reaction whereas the preexponential term showed a significant dependence on the reaction temperature. Both imipramine hydrochloride and trimipramine maleate showed two main steps of decomposition. Each step proved to be a first-order reaction. The rate constant was calculated for each step, and the results were analyzed statistically. 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 166,179, 2003 [source]


    Kinetics of the thermal decomposition of bis(trifluoromethyl) peroxydicarbonate, CF3OC(O)OOC(O)OCF3

    INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 1 2003
    Maximiliano A. Burgos Paci
    Thermal decomposition of bis(trifluoromethyl) peroxydicarbonate has been studied. The mechanism of decomposition is a simple bond fission, homogeneous first-order process when the reaction is carried out in the presence of inert gases such as N2 or CO. An activation energy of 28.5 kcal mol,1 was determined for the temperature range of 50,90C. Decomposition is accelerated by nitric oxide because of a chemical attack on the peroxide forming substances different from those formed with N2 or CO. An interpretation on the influence of the substituents in different peroxides on the OO bond is given. 2002 Wiley Periodicals, Inc. Int J Chem Kinet 35: 15,19, 2003 [source]


    Preparation and characterization of poly(dimethyldiallylammonium chloride) with high molar mass using high purity industrial monomer

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2010
    Xu Jia
    Abstract A preparation method for high molar mass poly(dimethyldiallylammonium chloride) (PDMDAAC) is reported in this article. PDMDAAC was prepared by using the high purity industrial grade dimethyldiallylammonium chloride (DMDAAC) monomer from one-step method and ammonium persulphate (APS) as the initiator. The initiator was added all at once and the reaction temperature was increased stepwise to complete the polymerization gradually. The effects of several polymerization condition variables on the intrinsic viscosity value ([,]) and monomer conversion rate (Conv.) of product PDMDAAC were investigated, respectively. The variables included: T1 (42.0 to 52.0C), T2 (47.5 to 57.5C), T3 (55.0 to 75.0C), m(DMDAAC) (60.0 to 70.0%), m(APS) : m(DMDAAC) (0.25 to 0.45%), m(Na4EDTA) : m(DMDAAC) (0 to 0.0071%). Under an optimum condition of T1 = 46.0C, T2 = 52.5C, T3 = 65.0C, m(DMDAAC) = 65.0%, m(APS) : m(DMDAAC) = 0.35%, m(Na4EDTA) : m(DMDAAC) = 0.0035%, the maximum [,] of obtained product PDMDAAC reached 3.43 dL/g, at a Conv. of 100.00%. The Mw of the product measured with GPC-MALLS was 1.034 106, polydespersity Mw/Mn was 2.421, and the Rg was 60.3 nm. The structure and properties of products were characterized by FTIR and NMR. Thermal decomposition was determined by TGA-DSC. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]


    The role of specific interactions in crystalline complex formation.

    JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 2002
    10-bis(4-bromophenyl)-, 10-dihydroanthracene with dimethyl sulfoxide, 10-dihydroxy-, Structural, thermochemical analysis of inclusion compounds of cis -, trans -
    Abstract Referring to a crucial problem in crystal engineering and co-crystallization of host,guest complexes, whether the non-covalent supramolecular interactions existing in a pre-crystalline solution state may determine the subsequent crystal structure, the particular inclusion properties of host compounds 1, cis - and 2, trans -9,10-bis(4-bromophenyl)-9,10-dihydroxy-9,10-dihydroanthracene, with dimethyl sulfoxide (DMSO) were studied by using x-ray structure analysis and calorimetric methods. Both hosts form crystalline inclusion complexes with DMSO showing 2:3 (1DMSO) and 1:4 (2DMSO) host:guest composition. The crystal structure of 1DMSO (2:3) is dominated by a strong bifurcated acceptor-type H bond interaction involving 1 and one of the DMSO molecules. Titration calorimetric investigations in solution also confirm the formation of a stable 1DMSO (1:1) complex unit, suggesting that for crystal nuclei of 1DMSO (2:3) the pre-formed 1:1 host,guest complex is the relevant building block while the additional molecules of DMSO fill lattice voids. In contrast, compound 2 with a trans configuration of the two hydroxy groups gives much weaker complexation with DMSO in solution, which is in agreement with single H-bond interaction, also realized in the crystal structure of the respective inclusion complex. Thermal decomposition (TG,DSC) measurements of the crystalline complexes supply supporting data for these findings. Copyright 2002 John Wiley & Sons, Ltd. [source]