Thermal decomposition of silver(I) and mercury(I) anthranilates and salicyloaldoximates

The processes of thermal decomposition of silver(I) and mercury(I) anthranilates and salicyloaldoximates were studied. Thermal, chemical and X-ray analyses and infrared spectroscopy were used to determine the mechanisms of decomposition of these complexes. The factor determining the decomposition is the character of the Ag⁺ and Hg ₂ ²⁺ ions, which are easily reduced to free metals. The final reaction product of the compounds of silver is the pure metal; the compounds of mercury are volatilized completely when heated.     

Thermal decompositions of silver carboxylates

The thermal decompositions of the even silver dicarboxylates from silver oxalate to silver sebacate were studied. In vacuum, the dicarboxylates decomposed to give metallic silver, CO₂ and organic diradicals as primary products, and polymers as secondary products. The higher silver dicarboxylates were much more stable to thermal treatment than silver oxalate, probably due to the initiation of decomposition of all carboxylates except silver oxalate by the rupture of a Ag-O and not a C-C bond.

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Zusammenfassung Die thermische Zersetzung der geradzahligen Silberdicarboxylate Silberoxalat bis-sebacinat wurde untersucht. Unter Vakuum zersetzen sich die Dicarboxylate zu metallischem Silber, CO₂ und organischen Diradikalen als Primärprodukt und Polymeren als Sekundärprodukt. Die höheren Silberdicarboxylate sind wesentlich stabiler als das Oxalat, wahrscheinlich weil bei ihnen die Zersetzung von der Spaltung einer Ag-O-Bindung und nicht einer C-C-Bindung wie beim Oxalat ihren Anfang nimmt.

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, . , — . , . , , , Ag-O, -.

     

Thermal decomposition of oxalates. Part 17. Thermal decomposition of manganese(II) oxalate in a nitrogen atmosphere

Comparative studies of the kinetics of the isothermal and nonisothermal dehydration and decomposition of manganese(II) oxalate in an atmosphere of nitrogen are reported. Agreement between the values of the energy of activation for the isothermal and the nonisothermal dehydration at high heating rates was obtained. At low heating rate, the value obtained for the energy of activation is comparable with the enthalpy of dehydration. Values of 143 and 242 kJ mole^?1 were obtained for the energy of activation of the isothermal and nonisothermal decomposition, respectively. The difference is attributed to the condition of the anhydrous salt used in both cases. The theory of absolute reaction rate is applied and the parameters obtained are discussed.     

Thermal decomposition of basic zinc carbonate in nitrogen atmosphere

Dynamic kinetic analyses were performed on basic zinc carbonate using TG and DTA measurements in N₂. The thermal behavior and the kinetics of decomposition were studied. The effect of procedural variables on the kinetics was investigated. In this work, the procedural variables included heating rate and sample size. To estimate the activation energy of decomposition, the Friedman isoconversional method was applied. The activation energy (E_a) was calculated as a function of conversion (a).     

Thermal decomposition of some N-oxide complexes of cobalt(II), nickel(II) and copper(II) carboxylates

Thermal decomposition of mono pyridine N-oxide complexe; of cobalt(II), nickel(II) and copper(II) propionates and mono quinoline N-oxide complex of copper(II) ben zoate has been studied by TG and DTA techniques. These dimeric complexes are stable upto 350–380 K and decompose in two stages: (i) successive elimination of the two ligand molecules (mostly endothermic); and (ii) decomposition of the resulting anhydrous metal(II) carboxylates by an exothermic multistep process in air.

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Zusammenfassung Die thermische Zersetzung der Monopyridin N-oxidkomplexe der Kobalt(II)-, Nickel(II) und Kupfer(II)-propionate sowie des Monochinolin N-oxidkomplexes von Kupfer(II)-benzoat wurden durch TG und DTA-Methoden untersucht. Diese dimeren Komplexe sind bis zu 350–380 K stabil und werden in zwei Stufen zersetzt: (i) sukzessive Eliminierung der zwei Ligandmoleküle (hauptsÄchlich endotherm); und (ii) Zersetzung der entstehenden wasserfreien Metall(II)carboxylate durch einen mehrstufigen exothermen Vorgang in Luft.

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Résumé On a étudié, par TG et ATD, la décomposition thermique des propionates des complexes mono-pyridine N-oxyde de cobalt(II), de nickel(II) et de cuivre(II) ainsi que du benzoate mono-quinoline N-oxyde de cuivre(II). Ces complexes dimères sont stables jusqu'à 350–380 K et se décomposent en deux étapes: (i) élimination successive des deux moléculesligands (la plupart du temps endothermique); et (ii) décomposition des carboxylates anhydres des métaux(II) formés par un processus en plusieurs étapes dans de l'air.

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-N- (II), (II) (II), -N- (II). 350–380 : (1) (2) .

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The authors are thankful to Dr. R. K. Dewan, Head of the Chemistry Department, University of Jammu, Jammu for providing necessary facilities in the department. The authors are also indebted to Dr. O. P. Vig, Head of the Chemistry Department, Panjab University, Chandigarh for assistance provided. One of the authors (R. K.) is grateful to University Grants Commission, New Delhi for the award of Junior Research Fellowship.     

Thermal decomposition of transition metal carboxylates

Thermal decomposition of anhydrous Cu(HCOO)₂ (1) affords H₂, CO, CO₂, H₂O, HCuOOH, CuHCOO, Cu, and the polymeric product, which contains -CH₂O,-C(O)OH-, and -RCH-0- groups. Dccomposition of1 proceeds in stages with formation of copper(I) formate as an intermediate. Possible pathways of decomposition ofI, including isomeric forms of the HCO₂ radical as intermediates, were analyzed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1406–1412, June, 1996.     

Thermal decomposition of transition metal carboxylates

Thermal solid-phase decomposition of anhydrous copper(ii) formate has been studied at 120–180 ° The rate of gas evolution during the decomposition depends on the depth of conversion and can be presented as the sum of first-order reaction rates and the rate of the autocatalytic process (a second-order reaction). The evolution of the solid phase during thermolysis has been observed by optical microscopy. The decomposition of copper formate is a complex topochemical process, a combination of homogeneous and heterogeneous transformations and dispersion of large crystals.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. l, pp. 72–76, January, 1996.     

Thermal decomposition of transition metal carboxylates

Dynamics of changes in microstresses during thermal decomposition of Cu(HCOO)₂ crystals and their effect on the thermal decomposition kinetics were studied by IR spectroscopy at 105 to 120 °C. The formation of solid intermediate HCOOCu was observed, and the dynamics of its accumulation was followed. Kinetic regularities of transformation of HCOO groups were compared with those for gas evolution.For Communication 1, see Ref. 1.Translated from Izvestiya va Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 350–354, February, 1996.     

Thermal decomposition of Prussian blue under inert atmosphere

The thermal decomposition of Prussian blue (iron(III) hexacyanoferrate) under inert atmosphere of argon was monitored by thermal analysis from room temperature up to 1000?°C. X-ray powder diffraction and ⁵⁷Fe M?ssbauer spectroscopy were the techniques used for phase identification before and after sample heating. The decomposition reaction is based on a successive release of cyanide groups from the Prussian blue structure. Three principal stages were observed including dehydration, change of crystal structure of Prussian blue, and its decomposition. At 400?°C, a monoclinic Prussian blue analogue was identified, while at higher temperatures the formation of various polymorphs of iron carbides was observed, including an orthorhombic Fe₂C. Increase in the temperature above 700?°C induced decomposition of primarily formed Fe₇C₃ and Fe₂C iron carbides into cementite, metallic iron, and graphite. The overall decomposition reaction can be expressed as follows: Fe₄[Fe(CN)₆]₃·4H₂O????4Fe?+?Fe₃C?+?7C?+?5(CN)₂?+?4N₂?+?4H₂O.     

Phosphane/phosphite silver(I) carboxylates as CVD precursors

The preparation of [L_mAgO₂CR] (L = PⁿBu₃, P(OMe)₃, P(OEt)₃; m = 1, 2; R = singly-bound organic group) and [L_mAg–E–AgL_m] (L = PⁿBu₃; E = oxalate; m = 1, 2, 3) is described. Their use as spin-on and CVD precursors is reported. SEM and EDX studies show that closed and homogeneous silver films with admirable conductivity could be obtained.     

Pyrolytic decomposition of some even chain length copper (II) carboxylates

The products of the pyrolytic decomposition of some even chain-length copper (II) carboxylates from decanoate to octadecanoate inclusive have been identified, using a flow system, to be copper, carbon dioxide, a carboxylic acid and an odd chain-mength alkene. These products are similar to those reported for the decomposition of mercury (II) carboxylates. The unexpectedly low (less than unity) CO₂/soap ratio was attributed to the reduction of the CO₂ to carbon monoxide. The carboxylic acid was characterised by wet chemical tests, determining the melting points of the acid and its amide derivative and matching its IR spectrum with that of the authentic acid. Elemental analysis and wet chemical tests were employed for the identification of the alkene.The products of decomposition and mechanism proposed to account for the degradative route of the systems show that good quality thin solid copper oxide films may only be obtained from the decomposition of copper (II) carboxylates if the carrier gas is non-inert (e.g. oxygen).

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Zusammenfassung Als Produkte der pyrolytischen, in einem Gasstrom vorgenommenen Zersetzung einiger Kupfer (II) -Karboxylate mit geradzahliger Kohlenstoffatomzahl der Kette (Dekanoat bis einschließlich Octadekanoat) wurden Kupfer, Kohlendioxid, eine Karbonsäure und ein Alken mit ungerader Kohlenstoffatomzahl identifiziert. Diese Produkte sind ähnlich denen, die bei der Zersetzung von Quecksilber (II) -Karbcxylaten auftreten. Das unerwartet niedrige CO₂/Seife-Verhältnis (kleiner als 1) wurde der Reduktion von CO₂ zu Kohlenmonoxid zugeschrieben. Die Karbonsäure wurde durch naße chemische Tests, durch Bestimmung des Schmelzpunktes der Säure und dem des Amidderivats und durch Vergleich des IR-Spektrums mit dem der authentischen Säure identifiziert. Elementaranalyse und naße chemische Tests wurden zur Identifizierung der Alkene herangezogen. Die Zersetzungsprodukte und der zur Erklärung des Abbaus des Systems vorgeschlagene Mechanismus zeigen, daß dünne feste Kupferoxidschichten in guter Qualität nur bei der Zersetzung von Kupfer (II) -Karboxylaten in nichtinertem Trägergas (z. B. in Sauerstoff) erhalten werden.

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, , . , , . , . ( ) — . , , . . , , , , - - , , .

     

Morphology of solid photochemical decomposition products of silver carboxylates

The formation of solid photochemical decomposition products of silver carboxylates with long linear hydrocarbon chains and its variation in the course of reaction was investigated. At the initial stage of photolysis, particles of silver are formed with the overall situation analogous to that in the case of other silver salts. After the degree of decomposition has reached 20%, the formation of a space-ordered structure of solid products in the form of alternating volume lamellae of paraffin and silver is observed. The average distance from one lamella edge to the next lamella edge is dependent upon the length of the methylene chains of silver carboxylates and the intensity of irradiation. The results obtained are discussed from the point of view of possible spinodal character of decomposition of intermediate solid solution paraffin-silver carboxylate.     

Thermal decomposition of copper(II) benzenetricarboxylates in air atmosphere

The conditions of thermal decomposition of copper(II) benzenetricarboxylates in air atmosphere at heating rates of 10 and 5 deg·min^–1 were studied. At 10 deg · min^–1, the hemimellitate and trimesinate of copper(II) lose crystallization water and then decompose directly to CuO, whereas at 5 deg·min^–1 they decompose to CuO through Cu₂O. The trimellitate of copper(II) heated at various rates decomposes in the same way: it loses 1 water molecule and then decomposes directly to CuO.     

Thermal decomposition of thorium(IV) benzenedicarboxylates in air atmosphere

The conditions of thermal decomposition of Th(IV) benzenedicarboxylates have been studied. On heating, thorium(IV) phthalate and isophthalate are dehydrated and the anhydrous complexes decompose to ThO₂ with intermediate formation of a mixture of ThOCO₃ and carbon.Th(IV) terephthalate obtained at room temperature loses crystal water and then decomposes directly to ThO₂, while the complex isolated from a hot solution on heating is first dehydrated, and the anhydrous complex is decarboxylated and then decomposed to ThO₂ with the intermediate formation of ThOCO₃.The activation energies of dehydration have been calculated for the Th(IV) benzenedicarboxylates.

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Zusammenfassung Die Bedingungen der thermischen Zersetzung von Th(IV)-benzendicarboxylaten wurde untersucht. Thorium(IV)-phthalat und- isophthalat werden beim Erhitzen zunÄchst dehydratisiert, danach zersetzen sich die wasserfreien Komplexe über ein intermediÄr auftretendes Gemisch von ThOCO₃ und Kohlenstoff zu ThO₂. Bei Raumtemperatur erhaltenes Th(IV)-terephthalat verliert Wasser und zersetzt sich dann direkt zu ThO₂, wÄhrend der aus einer hei\en Lösung isolierte Komplex nach der als erster Schritt verlaufenden Dehydratisierung zunÄchst decarboxyliert wird und sich dann über ThOCO₃ als Zwischenprodukt zu ThO₂ zersetzt. Die Aktivierungsenergien der Dehydratisierung der Th(IV)-benzendicarboxylate wurden berechnet.

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. , ThO₂ ThOCO₃ . , , , ThO₂. , , , , H₂ ThOCO₃ . .

     

Thermal decomposition of some dihalotetramminecobalt(III) nitrates

The thermal decomposition of some dihalotetramminecobalt(III) nitrates [tetrammire =(NH₃)₄, (NH₃)₂(en), (NH₃)(dien), (en)₂, (pn)₂, (trien), etc.] with different degrees of chelation was studied by various thermoanalytical techniques. A partial oxidation—reduction was observed for these complexes above 200°C which was indicated by a rapid TG mass-loss and a large exothermic DTA peak. A relative order thermal stability is reported.     

Thermal decomposition of Fe(II) carboxylates: Comparison of decomposition processes between the formate and malonate

The thermogravimetric curves of Fe(II) formate dihydrate, Fe(for)₂ · 2H₂O, and Fe(II) malonate dihydrate, Fe(mal) · 2H₂O, in an argon atmosphere were obtained. The products at each decomposition stage were determined by Mössbauer spectroscopy, IR, powder X-ray analysis and gas chromatography. The dehydration of Fe(for)₂ · 2H₂O took place in two steps to form an anhydrous salt in the crystalline state, while Fe(mal) · 2H₂O lost 2 mole of H₂O in one step to form an anhydrous salt in the amorphous state. The decomposition processes of Fe(for)₂ and Fe(mal) were represented as Fe(for)₂→Fe₃O₄→FeO and Fe(mal)→FeO→α-Fe, respectively.     

Thermal decomposition of silver carbonate

Conflicting results have been reported by different workers on the thermal decomposition of silver carbonate, Ag₂CO₃. In the present study, the decomposition mechanism was elucidated by various analytical methods; gas analysis (differential thermal gas analyses) in helium, carbon dioxide and oxygen flows with and without a P₂O₅ trap or a KOH trap, DTA-TG in a carbon dioxide flow and high-temperature X-ray diffraction analysis in a carbon dioxide flow. The gas evolution at ca. 200?C consisted of carbon dioxide. A simultaneous evolution of carbon dioxide and oxygen occurred at ca. 400?C. Two endothermic peaks (ca. 189 and 197?C) without weight change during the heating in a carbon dioxide atmosphere were due to the phase transition of silver carbonate from the normal viaΒ toα phase. The reverse transition occurred during the cooling.     

Thermal decomposition of basic aluminium-ammonium sulfate (BAAS) in hydrogen atmosphere

The stages of thermal decomposition of basic aluminium-ammonium sulfate (BAAS) in hydrogen atmosphere were studied with use of differential thermal analysis (DTA), thermogravimetric (TG), X-ray diffraction phase analysis (XRD), and chemical analyses. It has been found that hydrogen greatly influences the process of the desulfurization of the investigated compound: this process occurs at lower temperatures as compared to the desulfurization process in air. The final decomposition product of the basic salt at 1223 K is-Al₂O₃. The experimental part is preceded by the thermodynamic analysis of the desulfurization process of BAAS in hydrogen atmosphere, and its results have been correlated with experimental tests.

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Zusammenfassung Die Stufen der thermischen Zersetzung von basischem Aluminium Ammonium Sulfat (BAAS) in WasserstoffatmosphÄre wurden unter Verwendung von Differenzthermoanalyse (DTA), Thermogravimetrie (TG), röntgenographischer Phasenanalytik (XRD) und chemischer Analytik untersucht. Es wurde festgestellt, dass Wasserstoff den Desulfurierungsprozess der untersuchten Verbindung stark beeinflusst, indem dieser bei tieferer Temperatur ablÄuft als die Desulfurierung in Luft. Das Endprodukt der Zersetzung des basischen Salzes bei 1223 K ist-Al₂O₃. Die experimentellen Resultate wurden mit den Ergebnissen einer vorgÄngig durchgeführten thermodynamischen Betrachtung der Desulfurierung von BAAS in WasserstoffatmosphÄre korreliert.

     

Thermal decomposition of Cu(I) phosphine complexes

The thermal decomposition of Cu(I) phosphine complexes of the general types (CuXPPh₃)₄, [CuX(PPh₃)₂] and [CuX(PPh₃)₃] was investigated.The thermal decomposition of (CuXPPh₃)₄, where X denotes Cl^–, Br^–, I^–, NO ₃ ^– and PPh₃=P(C₆H₅)₃, occurs with formation of a phosphine oxide intermediate. For the remaining complexes this intermediate was not proved in the thermal decomposition.

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Zusammenfassung Die thermische Zersetzung der Cu(I)-Phosphinkomplexe vom allgemeinen Typ (CuXPPh₃)₄ und [CuX(PPh₃)₂], wie auch [CuX(PPh₃)₃] wurde untersucht. Die thermische Zersetzung von (CuXPPh₃)₄, wobei X=Cl^–, Br^–, I^– und NO ₃ ^– bedeutet und PPh₃=P(C₆H₅)₃, verläuft unter Bildung eines Phosphinoxid Zwischenproduktes, bei den übrigen Komplexen konnte dieses im Laufe der thermischen Zersetzung nicht nachgewiesen werden.

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Résumé On a étudié la décomposition thermique des complexes phosphine-Cu(I) de formule générale (CuXPPh₃)₄, [CuX(PPh₃)₂], [CuX(PPh₃)₃]. La décomposition thermique de (CuXPPh₃)₄, où X désigne Cl^–, Br^–, I^– et NO ₃ ^– , et PPh₃=P(C₆H₅)₃, s'effectue avec formation d'un oxyde de phosphine intermédiaire; avec les autres complexes, cet intermédiaire n'a pas été mis en évidence au cours de la décomposition thermique.

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(CuXPPb₃)₄ [CuX(PPh₃)₂] [CuX(PPh₃)₃]. (CuXPPh₃)₄, X=Cl^–, Br^–, I^–, NO ₃ ^– , PPh₃=(₆₅)₃ . .