Final Decomposition Products Research Articles

Synthesis, characterization and thermal behavior of heterobimetallic carbonyl compounds of the type [W(CO) 4(bipy)(CuX)](X = Cl, N 3, ClO 4 and BF 4)

Four new heterobimetallic metal carbonyls were synthesized by the reaction of [W(CO) 4(bipy)] ( 1) with copper(I) compounds leading to species with the general formula [W(CO) 4(bipy)(CuX)] (X = Cl, N 3, ClO 4, BF 4) ( 2–5). The metal carbonyl compounds were characterized by elemental analysis, infrared and UV-visible electronic spectroscopy and thermogravimetric analysis. The IR data for 2–5 show carbonyl stretching band patterns similar to compound 1; ie they exhibit the same number of bands. The UV-vis results show a dissociation reaction generating the starting compound 1 and CuX as consequence of a weak interaction between 1 and CuX. Thermal decomposition mechanisms as well as the thermal stability are influenced by the CuX fragments. The thermal stability decreases in the order [W(CO) 4(bipyl)]>[W(CO) 4(bipy)(CuCl)]>[W(CO) 4(bipy)(CuBF 4)]. The X-ray results show the formation of WO 3, CuWO 4, Cu 2O and CuO as final decomposition products.

Thermal decomposition behaviour of some trivalent transition and inner-transition metal complexes of triethanolamine

Abstract Thermal decompositions of triethanolamine complexes of Cr(III), Fe(III), Ru(III), Rh(III), La(III), Ce(III) and Nd(III) in dynamic nitrogen and air atmosphere were studied by DTA, TG and DTG. The final solid decomposition products were identified by X-ray powder diffractometry. The thermal stability of the complexes in the solid state was discussed. These complexes exhibit a considerable thermal stability and the stability order was found to be: Nd(III) > La(III) ≅ Ce(III) > Cr(III) > Fe(III) > Ru(III) > Rh(III).

Synthesis, characterization and thermal behaviour of adducts

The photoproduct of octacyanomolybdate(IV) and -tungstate(IV) with ethylenediamine and triethylenetetramine give complexes of the type K3[Mo(O2)(O)(OH)(C9H7ON)]·3C9H7ON I, K2[W(O2)(O) (C9H7ON)3] II and K3[Mo(CN)3(OH)4(C9H7ON)]·2C9H7ON·3H2O III with 8-quinolinol (oxine). The IR spectra of the complex III shows the presence ofv(CN) peaks in the range 2047–2108 cm−1 and oxine groupv(C-O) in the complex I, II and III in the range of 1100–1150 cm−1. The lower region of IR spectra shows the M=O stretching while the higher thev(N-H) andv(OH). Thermal studies show the removal of uncoordinated water at 131‡C from complex III. The decomposition of complexes I and II start from 150 and 212‡C respectively. Oxine and cyano molecules were removed in stages at higher temperatures. The final product of the thermal decomposition was oxide which was of polymeric nature. The kinetic parameters viz. order of reaction ‘n’ and activation energy ‘E’ were determined by different methods.

Effects of the preparation procedure and additives on surface texture of nickel and cobalt oxides as final decomposition products of nickel and cobalt oxysalts

The effects of preparation procedure and readily decomposable salt additives, namely (NH 2 ) 2 CO and NH 4 NO 3 , on the texture of NiO and Co 3 O 4 produced by calcination of Ni(NO 3 ) 2 ·6H 2 O and Co(NO 3 ) 2 ·6H 2 O were investigated. Textural characteristics were assessed via analysis of nitrogen adsorption isotherms, using a number of widely-accepted methods. The thermal genesis courses of NiO and Co 3 O 4 , from additive-containing and additive-free oxide precursors were explored using thermogravimetry, differential thermal analysis and X-ray diffractometry (XRD). The results of surface texture and XRD analyses were largely in agreement and showed that pores are modified. An impregnation procedure using salt additives to NiO and Co 3 O 4 resulted in a marked increase of surface area (from 23 to 65 m 2 g −1 for NiO and from 18 to 82 m 2 g −1 for Co 3 O 4 ). This increase is most likely due to the evolved gases and the consequent fragmentation of particles and the widening of pores.

Thermal decomposition characteristics of ammonium hexachlorometallate(IV) complex salts of platinum metals

The thermal decomposition behaviour of ammonium hexachlororuthenate(IV), palladate(IV), osmate(IV), iridate(IV) and platinate(IV) was investigated in nitrogen atmosphere using TG and DTA techniques. X-ray powder diffractometry was used to identify the final solid decomposition products. The thermal decomposition of the complex salts yields the respective metals as the final residue. The thermal decomposition mechanism of these complex salts is suggested and the thermal stability in the solid state is discussed in terms of inorganic energetics, such as the ligand field stabilization energy and lattice energy. The sequence of thermal stability of the complex salts was found to be Os(IV) > Ir(IV) > Pt(IV) > Pd(IV).

Electron Beam Atmospheric Pressure Cold Plasma Decomposition of Carbon Tetrachloride and Trichloroethylene

The cold plasma decomposition of carbon tetrachloride (CCl 4 ) and trichloroethylene (C 2 HCl 3 ) at dilute concentrations in dry and wet air of atmospheric pressure was investigated. The cold plasma was generated in a tunable plasma reactor, where the electron concentration is controlled by an electron beam and the average electron energy is controlled by a superimposed sub-breakdown electric field. The energy expense for decomposition, i.e., the electron beam energy per molecule decomposed, as well as the intermediate and final decomposition products were determined. Moreover, likely reaction mechanisms for the decomposition of CCl 4 and C 2 HCl 3 are presented. These mechanisms are based on bimolecular dissociative electron attachment for both CCl 4 and C 2 -HCl 3 and additionally a chlorine chain reaction for C 2 HCl 3 . The present work provides a reference for the development of an advanced oxidation process on the basis of a tunable plasma reactor. Such a process would be especially suitable for the treatment of air contaminated with chemical compounds that dissociatively attach electrons.

Thermal properties of zinc butyrate complex compounds. Part 1: Urea and thiourea ligands

The new zinc(II) complexes of general formula Zn(CH 3CH 2CH 2COO) 2· nL (where L = thiourea, urea; n = 1 or 2) were prepared and identified. The thermal properties of this compounds were investigated by thermal analysis (TG, DTG, DTA, DSC, DDSC). The gaseous products of thermal decomposition were detected by IR spectroscopy and mass spectroscopy. The final product of thermal decomposition was determined by X-ray patterns.

Investigations on thermal stability of adduct aluminium nitrate(V)-urea (1/6)

The adduct of Al(NO3)3·6CO(NH2)2 has been prepared and characterized by means of chemical analysis, IR spectroscopy, X-ray patterns and microscopy.A thermoanalytical study of Al(NO3)3·6CO(NH2)2 as well as urea, for comparison purposes, under conventional dynamic and quasi-isothermal—quasi-isobaric conditions in air has been carried out.It has been found that the adduct is thermally stable up to about 200°C, i.e. up to higher temperature than the decomposition temperature of the constituent compounds. The thermal decomposition mechanism of the adduct is complex, thus infrared spectroscopy and X-ray diffraction techniques have been used to determine the intermediate products. Aluminium oxide(III) is the final decomposition product.

Adsorption and decomposition of ethylene and acetylene on Fe(100)

The adsorption of C 2H 4 and C 2H 2 on the clean, C- and O-covered Fe(100) surface was studied using HREELS, with additional information provided by TPD, AES and LEED. On the clean surface, C 2H 4 adsorbed molecularly on this surface in a di-σ-bonded configuration at 100 K. The di-σ-bonded C 2H 4 desorbed at 240 K or decomposed to form the methylidyne (CH) and ethynyl (CCH) species below 260 K. Hydrogen is the only desorption product of C 2H 4 decomposition. Acetylene adsorbs on the clean Fe(100) surface in a structure with hybridization of ∼ sp 3. At lower exposure (< 0.2 L), C 2H 2 decomposes to form CH and CCH at 253 K. At higher exposure (>0.2 L), C 2H 2 partially dehydrogenates and hydrogenates to form CH, CCH and CHCH 2 at the adsorption temperature of 100 K. When the surface is warmed to 393 K, a CCH 2 species is formed by the dehydrogenation of CHCH 2. The final decomposition product of ethylene is a c(2 × 2)-C surface, formed by heating the adsorbate to 523 K. A ( 1 1 −1 2 ) -C surface with 0.81 ML coverage is obtained by heating the acetylene adsorbed layer to 553 K. Preadsorbed carbon and oxygen block the chemisorption of di-σ-bonded C 2H 4 and induce physisorption of C 2H 4 at 100 K. Preadsorbed oxygen appears to inhibit the dehydrogenation of di-σ-bonded C 2H 4 and induces the adsorption of π-bonded C 2H 4. A carbon precovered surface shows a site-blocking effect for the adsorption of C 2H 2.

Preparation, chemical characterization and thermal study of 2-aminopyridinium salts of square-planar 1,2-dithiooxalato- S, S′ metal complexes (M  Ni II, Pd II and Pt II)

Reaction of an aqueous solution of 2-aminopyridinium chloride with the appropriate K 2[M(S 2C 2O 2) 2] salt yielded microcrystalline powders of three complexes of the formulae (HC 5H 6N 2) 2[Ni(S 2C 2O 2) 2] ( 1), (HC 5H 6N 2) 2[Pd(S 2C 2O 2) 2] ( 2) and (HC 5H 6N 2) 2 [Pt(S 2C 2O 2) 2] ( 3), which were characterized by elemental analysis, IR and UV-vis spectroscopies, thermal analysis (TG, DTG and DTA) and X-ray powder diffraction techniques. The IR and UV-vis spectra support the presence of the aromatic cation and the complex anions. Single crystals of 1 were grown in silica hydrogel at room temperature employing test tubes. However, this compound is not stable on X-ray exposure and only the unit cell parameters were determined. The three compounds are isostructural, and crystallize in the monoclinic space group C2/ c with Z = 8. Thermal studies give evidence that the mechanism and the final solid products are strongly influenced by the atmospheric conditions. The final decomposition products were identified by elemental analysis and the X-ray powder diffraction technique. In an argon-oxygen atmosphere, thermal degradation led to a mixture of nickel sulphide, oxides and sulphate for 1, metallic palladium and palladium(II) oxide for 2, and platinum(O) for 3. Thermal decompositions in an inert atmosphere yielded nickel(II) sulphide, a mixture of Pd-PdS and metallic platinum, respectively.

Thermal decomposition of β-cyclodextrin inclusion complexes of ferrocene and their derivatives

The thermal decomposition of the solid inclusion complexes of ferrocene and its derivatives with β-CD was studied by DTA, TG and DTG. The inclusion complexes contain crystallization water and the first decomposition stage corresponds to the dehydration of the complexes. The second stage is related to the liberation of the ferrocene and its derivatives, and the degradation of the β-CD structure takes place in the third stage. However, the second and third stages of decomposition for some of the inclusion complexes occur in the same temperature ranges and are impossible to distinguish. The final decomposition products formed around 500°C consist mainly of Fe 2O 3. The thermal behaviour of physical mixtures of these ferrocene derivatives and β-CD was also investigated. The thermal analysis results show that the interaction of ferrocene and its derivatives with β-CD is a chemical phenomenon. The ferrocene derivatives gain an additional thermal stability after inclusion complexation into the β-CD cavity. Thermal analysis methods can be used satisfactorily for the recognition of inclusion complexation.

The in vitro degradation of cisatracurium, the R, cis-R′-isomer of atracurium, in human and rat plasma

To assess the mechanism and rate of in vitro degradation of cisatracurium in aqueous buffer and in human and rat plasma. Cisatracurium was incubated in aqueous buffer at various pH values or in human and rat plasma maintained at pH 7.4 with HEPES buffer. Cisatracurium and the degradation products, laudanosine and the monoquaternary alcohol, were quantitated by HPLC with use of fluorescence detection. In Sørenson's phosphate buffer, cisatracurium degraded spontaneously by a chemical process commonly referred to as "Hofmann elimination." The rate of degradation increased with increasing pH. From pH 6.4 to 7.8 there was a 6.5-fold increase in the rate of degradation of cisatracurium and, on a molar basis, the final decomposition product laudanosine accounted for all of the drug. At a pH of 7.4, cisatracurium degraded with a half-life of about 34.1 +/- 2.1 minutes. Cisatracurium incubated in human plasma degraded with a mean (+/- SD) half-life of 29.2 +/- 3.8 minutes, which is consistent with Hofmann elimination. Besides laudanosine, and unlike that observed in Sørenson's phosphate buffer, significant amounts of the monoquaternary alcohol were formed that slowly degraded to laudanosine. The micromoles of laudanosine formed eventually accounted for the total amount of cisatracurium incubated with human plasma. The monoquaternary alcohol appears to be a product of ester hydrolysis of a monoquaternary acrylate formed during the first step in Hofmann elimination. Evidence for esterase involvement at this step in the degradation of cisatracurium was based on inhibition studies with O-cresyl benzodioxaphosphorin oxide (CBDP), a specific carboxylesterase inhibitor. The addition of CBDP to human plasma completely blocked the formation of monoquaternary alcohol and converted the degradation of cisatracurium to total Hofmann elimination. In rat plasma cisatracurium was hydrolyzed, with a half-life of only 3 1/2 minutes, by carboxylesterases. The addition of CBDP increased the half-life to 25 minutes, which is consistent with Hofmann elimination. In human plasma the rate-limiting step in the degradation of cisatracurium is Hofmann elimination, with the initial formation of a monoquaternary acrylate. The observation that the monoquaternary alcohol results from ester hydrolysis of the monoquaternary acrylate by plasma esterase(s) explains the presence of the monoquaternary alcohol metabolite in human plasma during clinical studies with cisatracurium. The rapid hydrolysis of cisatracurium by rat plasma relative to human indicates a major species difference in plasma esterase(s).

Characterization of lanthanum oxide formed as a final decomposition product of lanthanum acetylacetonate: thermoanalytical, spectroscopic and microscopic studies

The porous and high surface area of lanthanum oxide was obtained as a final decomposition product of lanthanum acetylacetonate tetrahydrate. The decomposition course in dry nitrogen was thoroughly studied. Thermal processes occurring throughout the decomposition range (100–800 °C) were monitored by thermogravity; differential thermal analysis and infrared spectroscopy gaseous products. These processes were characterized on the basis of the solid products analyses, using X-ray diffractometry and IR-spectrometry. The results showed La(C 5H 7O 2) 3 completely decomposed to La 2O 3 at 730 °C, through amorphous and unstable intermediates La(CH 3COO)(C 5H 7O 2) 2 at 190 °C, La(CH 3COO) 2(C 5H 7O 2) at 225 °C, La(CH 3COO) 3 at 285 °C, La 2(CO 3) 3 at 390 °C and crystalline and stable La 2O 2(CO 3) at 430 °C. Gas phase decomposition products included propyne, acetone, carbon oxides, methane and isobutene. Methane and isobutene resulted from interfacial reactions involving the initial product (acetone). The ultimate products, La 2O 3 at 700 °C and 800 °C, are crystalline porous solids and having a surface area of 21 and 45 m 2/g respectively.

Thermal Decomposition of Lanthanum Trifluoromethanesulfonate

Abstract Lanthanum trifluoride (LaF3) has been obtained as the final product of the thermal decomposition of the corresponding trifluoro-methanesulfonate [La(OTf)3]. The decomposition processes up to 600 °C were characterized by means of TG, DTA, XRD and MS. It was revealed that the over all reaction scheme for the decomposition proceeds as follow: La(OTf)3→ LaF3 + 3SO2 + CO2 + CF3OCF3.

Thermal behaviour of some salicylato(amine)cobalt(III) complexes

The thermal dissociation of a number of salicylato(amine)cobalt(III) complexes has been studied by thermogravimetry, differential temperature analysis, UV-visible spectral analysis of intermediates and XRD of the final products. The final decomposition product was found to be Co 3O 4. Dissociation of [Co(en) 2(amine)salH](NO 3) 2 passed through the intermediate [Co(en) 2sal]. The intermediate was characterised by UV-visible spectral analysis. The complexes containing chelating salicylate were found to be more stable than those with unidentate ligand and also more stable than unbound salicylic acid.

Texture assessment of thoria as a final decomposition product of hydrated thorium nitrate and oxycarbonate

Th(NO 3) 4·5H 2O and ThO(CO 3)·0.5H 2O were used as parent compounds for the formation of ThO 2. Thermal processes involved during the course of decomposition up to 500°C in air were monitored by thermogravimetry, differential thermal analysis and infrared (IR) gas phase analysis. Intermediate and final solid products were characterized by IR spectroscopy and X-ray diffractometry. The results showed that Th(NO 3) 4·5H 2O is completely decomposed to ThO 2 at 300°C via three unstable intermediates: Th(OH)(NO 3) 3 at 165°C; ThO(NO 3) 2 at 210°C and ThO 1.75(NO 3) 0.5 at 250°C. Similarly, ThOCO 3·0.5H 2O is completely decomposed to ThO 2 at 300°C via the unstable intermediate ThO 1.5(CO 3) 0.5 at 160°C. Surface texture measurements and scanning electron microscopy showed that ThO 2, the final decomposition product at 500°C of both Th(NO 3) 4·5H 2O and ThO(CO 3)·0.5H 2O is crystalline and has surface areas of 32 m 2 g −1 and 56 m 2 g −1, respectively. ThO 2 formed from the nitrate is mainly microporous. However, ThO 2 obtained from the oxycarbonate contains different types of porosities.

Barium-copper(II) oxocarbon compounds: synthesis, crystal structures and thermal behaviours of [Ba(H 2O) 5][Cu(C 2O 4) 2(H 2O)] and [Ba(C 4O 4) 0.5(H 2O) 2] 2[Cu(C 4O 4) 2(H 2O 2

[Ba(H 2O 5][Cu(C 2O 4) 2(H 2O)] and [Ba(C 4O 4) 0.5(H 2O) 2] 2[Cu(C 4O 4) 2(H 2O) 2] were obtained as single crystals in water. The structures were determined from X-ray diffraction data. [Ba(H 2O) 5][Cu(C 2O 4) 2(H 2O)]: triclinic, space group P 1, a=9.209(2), b=10.938(1), c=6.547(1) A ̊ , α=100.83(1), β=99.65(2), γ=85.45(2)°, Z=2 ; [Ba(C 4O 4) 0.5(H 2O) 2] 2[Cu(C 4O 4) 2(H 2O) 2]: triclinic, space group P 1, a=7.752(1), b=10.445(2), c=7.420(1) A ̊ , α=99.24(1), β=113.20(1), γ=109.87(1)°, Z=1 . They are made of cationic layers separated by anions [Cu(C 2O 4) 2(H 2O)] 2− and [Cu(C 4O 4) 2(H 2O) 2] 2−, respectively. Both compounds were submitted to thermal gravimetric and differential analyses in an oxygenated atmosphere, up to 950 °C. Final decomposition products were (i) BaCuO 2 with small amounts of BaCO 3 and CuO for [Ba(H 2O) 5][Cu(C 2O 4) 2(H 2O)], and (ii) an equimolecular mixture of BaCuO 2 and BaCO 3 for [Ba(C 4O 4) 0.5(H 2O) 2] 2[Cu(C 4O 4) 2(H 2O) 2].

Synthesis of lead metaniobate by thermal decomposition of a coprecipitation product

The paper reports a new, nonconventional method for the preparation of oxygen-containing niobium compounds, based upon coprecipitation. The coprecipitation product of niobic acid with lead oxalate was used as precursor. Lead metaniobate was obtained by proper thermal treatment of the coprecipitate. The coprecipitate mechanism was studied and the optimal conditions for quantitative precipitation of niobium and lead were established. The mechanism of thermal decomposition of the coprecipitate was investigated by differential thermal analysis and X-ray powder diagrams. The final product of thermal decomposition, lead metaniobate, is formed at 850°C.

Physicochemical characterization of ceria as a final decomposition product of ammonium cerium (III) oxalate hydrate

High surface area and porous ceria was produced as a final decomposition product of ammonium cerium(III) oxalate hexahydrate. Thermal processes involved in the decomposition of (NH 4) 2Ce 2(C 2O 4) 4·6H 2O on heating up to 500°C in air were monitored by differential thermal analysis (DTA) and thermogravimetric analysis (TG) at various heating rates. Intermediates and final solid products were characterized by X-ray diffraction (XRD) and IR spectroscopy. The results indicated that the decomposition takes place via five weight loss processes; three endothermic with peaks at 110, 170 and 290°C and two exothermic at 320 and 335°C. The formation of anhydrous ammonium salt occurs at 170°C, and this decomposes at 290°C giving rise to the unstable intermediate hydrogen ceric oxalate, the latter decomposing immediately to Ce 2(CO 3) 3 and Ce 2(CO 3) 2 at 320°C. The unstable carbonates undergo an oxidative decomposition to give the final product, CeO 2, at 335°C. Surface texture analysis and scanning electron microscopy showed that CeO 2, when produced at 300 and 400°C, had a surface area of 130 m 2 g −1 and 120 m 2 g −1, respectively and was a crystalline porous material.

Characterisation and activity of praseodymium oxide catalysts prepared in different gases from praseodymium oxalate hydrate. Microscopic, thermogravimetric and IR spectroscopic studies

PrO1.833 and Pr2O3 catalysts have been obtained as final decomposition products of Pr2(C2O4)3· 10H2O in different gases (O2, N2 and H2). The decomposition processes were characterized by thermogravimetric (TG) and differential thermal analysis (DTA), X-ray diffraction (XRD) and IR spectroscopy of the solid-phase products. The results indicate that the compound dehydrates in three steps at 100, 150 and 380 °C and that the anhydrous oxalate decomposes at 445 °C to form two phases of Pr2O2(CO3) depending upon the atmosphere used for the reaction. On further heating PrO1.833 is formed at 550 °C in O2 and at 650 °C in N2. In contrast, Pr2O3 was formed at 650 °C in H2. Surface area measurements and scanning electron microscopy (SEM) have shown that PrO1.833 produced at 700 °C has a different surface area depending on the gas used: 43 and 64 m2 g–1 for O2 and N2, respectively. The surface area of Pr2O3 formed in H2 is 59 m2 g–1. The texture of the catalyst has been found to depend upon the decomposition atmosphere.IR spectroscopy has been used to analyse (qualitatively and quantitatively) the gas-phase reaction products between room temperature and 400 °C from the dehydrogenation and dehydration reactions of propan-2-ol over PrO1.833 and Pr2O3 catalysts. The results revealed that Pr2O3 is a selective dehydration catalyst at 275 °C, decomposing propan-2-ol into propene (ca. 80%). However, PrO1.833 is a dual function dehydration/dehydrogenation catalyst.