Mössbauer study of the thermal decomposition of iron(III) benzoate and iron(III) fumarate

The thermal decomposition of iron(III) benzoate, Fe(C₇H₅O₂)₃, and iron(III) fumarate pentahydrate, Fe₂(C₄H₂O₄)₃ 5 H₂O, containing uni- and bidentate ligands, respectively, has been investigated at various temperatures for different intervals of time in a static air atmosphere. Thermolysis of these compounds leads directly to the formation of α-Fe₂O₃ in the case of iron(III) benzoate and Fe₃O₄ in the case of iron(III) fumarate as the ultimate products, thus without undergoing reduction to the iron(II) state.     

Extraction-spectrophotometric determination of iron(III) by means of quinaldic acid-N-oxide

Summary A simple and sensitive method for the determination of iron(III) is described. It is based on the extraction of the yellow-coloured complex of iron with quinaldic acid-N-oxide in chloroform. The absorption maximum is at 380 nm with molar absorptivity ₃₈₀=1.03 · 10⁴. Beer's Law is obeyed over the range 0.6–6 ppm iron with relative standard deviation of +-0.3% (Sandell sensitivity 0.005 g/ml/cm²). The absorbance of the reagent blank is however high with consequent occasional disturbances, which are avoided when measured at 395 nm; molar absorptivity ₃₉₅=7.4 · 10³; effective concentration range 3–8 ppm iron with relative standard deviation +-0.5% (Sandell sensitivity 0.008g/ml/cm²). A fairly large number of common ions do not interfere. Job's method of continuous variations and Asmus method indicate a iron-reagent ratio of 13. Heterogeneous formation constant is K _D =2 · 10⁸.

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Extraktionsphotometrische Bestimmung von Eisen(III) mit Chinaldinsäure-N-oxid

Zusammenfassung Die einfache und empfindliche Bestimmung beruht auf der Extraktion des gelben Komplexes von Eisen(III) mit Chinaldinsäure-N-oxid in Chloroform. Das Absorptionsmaximum liegt bei 380 nm mit dem molaren Extinktionskoeffizient ₃₈₀=1.03 · 10⁴. Das Beersche Gesetz gilt im Bereich 0,6–6 ppm Eisen. Die relative Standardabweichung beträgt+-0,3% (Sandell-Empfindlichkeit 0,005g/ml/cm²). Die Absorption der Blindprobe ist jedoch hoch und verursacht manchmal Störungen, die beim Messen bei 395 nm vermieden werden; molarer Extinktionskoeffizient ₃₉₅= 7,4 · 10³; im Konzentrationsbereich 3–8 ppm Eisen beträgt die relative Standardabweichung+-0,5% (Sandell-Empfindlichkeit 0,008g/ml/cm²). Eine ziemlich große Zahl von Fremdionen bewirkt keine Störung. Methoden nach Job und Asmus liefern ein Verhältnis Eisen/Reagens wie 13. Die heterogene Bildungskonstante beträgt K _D =2 · 10⁸.

     

Estimation of the reactivities of some iron(III)oxides by emanation thermal analysis

A new method for estimating the reactivity of iron(III) oxide in a solid-state reaction is proposed. The method is based on the release of radioactive inert gas atoms (²²²Rn emanation) from a mixture of solids previously labeled with the inert gas atoms. By measuring the rate of release of emanation as a function of temperature, information can be obtained about the solid-state reaction and the final reaction product. The reactivities of some iron(III) oxide samples of different thermal histories and origins have been estimated in the solid-state reaction with zinc oxide labeled with the parent isotope of the emanation,²²⁸Th. The results of the proposed method, found more objective than common methods, are compared with surface area measurements on the tested samples.

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Zusammenfassung Eine neue Methode zur Abschätzung der Reaktivität von Eisen(III)oxid in der Festphasenreaktion wird vorgeschlagen. Die Methode beruht auf der Freisetzung radioaktiver Inertgasatome²²⁰Rn (Emanation) aus dem Gemisch ursprünglich mit Inertgasatomen markierter Festkörper. Durch Messung der Geschwindigkeit der abgegebenen Emanation in Abhängigkeit von der Temperatur können Informationen über die Festphasenreaktion und die Reaktions-Endprodukte erhalten werden. Die Ermittlung der Reaktivität einiger Eisen(III) oxid-Proben verschiedener Wärmegeschichte und verschiedenen Ursprungs wurde in der Festphasenreaktion mittels Zinkoxid durchgeführt, das mit dem Ausgangsisotopen der Emanation,²²⁸Th, markiert worden war. Die Resultate der vorgeschlagenen Methode, welche den üblichen gegenüber für objektiver gefunden wurde, werden mit den Oberflächenmessungen der geprüften Proben verglichen.

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Résumé On propose une nouvelle méthode pour estimer la réactivité de l'oxyde de fer(III) dans les réactions en phase solide. Elle repose sur le dégagement des atomes du gaz inerte radioactif²²⁰Rn (radon) du mélange des solides préalablement marqués par les atomes de gaz inerte. En mesurant la vitesse de dégagement du radon en fonction du temps on peut obtenir des renseignements sur la réaction dans l'état solide ainsi que sur le produit final de la réaction. On a pu estimer la réactivité en phase solide de quelques échantillons d'oxyde de fer(III), d'histoire thermique et d'origine différentes, vis-à-vis de l'oxyde de zinc marqué avec l'isotope parent du radon:²²⁸Th. On a comparé les résultats de la méthode proposée, estimée plus objective que celles habituellement utilisées, à ceux des mesures de surfaces spécifiques des échantillons étudiés.

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, . , , . : MOM, Netzch , , . - . , , , .

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Dedicated to Mrs. K. B. Zaborenko, Professor at the Moscow State University and leader of a research group developing emanation thermal analysis in the USSR, in honour of her anniversary.     

Interphase transport of iron(III) chloride by means of macrocyclic ligands

A study has been made for the first time of the transport of an iron(III) salt through a dichloroethane liquid membrane involving, by means of macrocyclic compounds containing donor oxygen, nitrogen, and sulfur atoms as well as certain functional groups in the ring. It has been established that the membrane transport of Fe(III) ions is determined to an appreciable extent by the properties of the anion of the salt.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 2, pp. 174–180, March–April, 1986.The authors express their deep gratitude to E. S. Levchenko for kindly supplying dithia-18-crown-6 and to A. G. Kol'chinskii and V. V. Pavlishchuk for preparing the DAADEN ligand.     

Formation of ceramic pigments of SnCr type. A study using thermal analysis methods

Methods of thermal analysis (DTA and chemical analyses of pigments calcined at various temperatures) have been used for the determination of the temperatures of formation of the structures CaSnO₃, CaSnSiO₅ and CaSiO₃. CaSnO₃ and CaSiO₃ are formed at a temperature of 1100°C. In the system SnCaSiCr, CaSnO₃ is formed at first; when the temperature reaches 1300°C it reacts with silica to give CaSnSiO₅. The activation energies of formation of the host structures were evaluated.     

Simultaneous differential rate determination of iron(II) and iron(III) by flow-injection analysis

Flow-injection procedures for the simultaneous spectrophotometric determination iron(II) and iron(III), relying on the different kinetic-catalytic behaviour of iron(II) and iron(III) in the redox reaction between leucomalachite green and peroxodisulphate with and without the presence of the activator 1,10-phenanthroline, are described. Exploiting the fact that one of the chemical reactions is very rapid whereas the other one is comparatively slower, two experimental procedures are presented. In the first, two individual zones of sample solution are injected simultaneously into separate carrier streams of reagent in a two-line system. Taking advantage of the different residence times of the samples in the manifold lines, the resulting colour formation is measured by a single optical detector with two separate flow cells aligned within the same optical path. The second approach is based on the use of a single-line flow-injection system, exploiting the formation of a double peak as a result of injecting a large sample zone, sandwiched between reagent zones of appropriate composition. In this manner two time-resolved signals for the kinetically governed processes can be obtained and thus used for quantification of the individual species.     

Mössbauer study of the thermal decomposition of some iron(III) dicarboxylates

The thermal decomposition of iron(III) succinate, Fe₂(C₄H₄O₄)₂(OH)₂ and iron(III) adipate pentahydrate, Fe₂(C₆H₈O₄)₃·5 H₂O, has been investigated at different temperatures for different time intervals in static air atmosphere using Mössbauer spectroscopy and nonisothermal techniques (DTG-DTA-TG). The reduction of iron(III) to iron(II) species has been observed at 533 K and 563 K in the case of iron(III) succinate and iron(III) adipate, respectively. At higher temperatures, α-Fe₂O₃ is formed as the final thermolysis product.     

Mössbauer study of the thermal decomposition of iron(III) citrate pentahydrate

The thermal decomposition of iron(III) citrate pentahydrate, Fe(C₆H₅O₇) · 5 H₂O, has been investigated at different temperatures in air using Mössbauer spectroscopy, nonisothermal techniques (DTA-TG) and X-ray diffraction. The reduction of iron(III) to iron(II) takes place at 553 K. At higher temperature the formation of -Fe₂O₃ and -Fe₂O₃ as the ultimate thermal decomposition products has been confirmed.

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Zusammenfassung Die thermische Zersetzung des Pentahydrates von Eisen(III)-citrat in Luft wurde bei verschiedenen Temperaturen durch Mössbauer-Spektroskopie, nicht-isotherme Techniken (DTA, TG) und Röntgendiffraktometrie untersucht. Die Reduktion von Eisen(III) zu Eisen(II) erfolgt bei 553 K. Bei höheren Temperaturen entstehen -Fe₂O₃ und -Fe₂O₃ als End-produkte der thermischen Zersetzung.

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(- ), - , (***) . 553 . , -F₂₃ -Fe₂O₃. .

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The authors are grateful to Dr. B. Mukherjee, C. G. C. R. Institute, Calcutta, for recording the X-ray diffraction pattern.     

Synthesis and the thermal decomposition of iron(III) tris(oxalato) ferrate(III) tetrahydrate

The paper describes the synthesis and thermal decomposition of Fe[Fe(C₂O₄)₃]4H₂O in air. The compound is completely dehydrated at 170°C and some reduction in the inner sphere iron(III) occurs. At 290°C, a mixture of ferric oxide and ferrous oxalate is obtained. Beyond 420°C, the decomposition is complete and final residue is ferric oxide. A probable reaction mechanism is proposed.     

Kinetics of thermal decomposition of iron(III) dicarboxylate complexes

Summary Tris(dicarboxylate) complexes of iron(III) with oxalate, maleate, malonate and phthalate viz. K₃[Fe(C₂O₄)₃]×3H₂O (1), K₃[Fe(OOCCH₂COO)₃]×3H₂O (2), K₃[Fe(OOCCH=CHCOO)₃]×3H₂O (3), K₃[Fe(OOC-1,2-(C₆H₄)-COO)₃]×3H₂O (4) have been synthesized and characterized using a combination of physicochemical techniques. The thermal decomposition behaviour of these complexes have been investigated under dynamic air atmosphere upto 800 K. All these complexes undergo a three-step dehydration/decomposition process for which the kinetic parameters have been calculated using Freeman-Carrol model as well as using different mechanistic models of the solid-state reactions. The trisoxalato and trismalonato ferrate(III) complexes undergo rapid dehydration at lower temperature below 470 K. At moderately higher temperatures (i.e. >600 and 500 K, respectively) they formed bis chelate iron(III) complexes. The trismalonato and trismaleato complexes dehydrate with almost equal ease but the latter is much less stable to decomposition and yields FeCO₃ below 760 K. The cis-dicarboxylate complexes particularly with maleate(2-) and phthalate(2-) ligands are highly prone to the loss of cyclic anhydrides at moderately raised temperatures. The thermal decomposition of the tris(dicarboxylato)iron(II) to iron oxide was not observed in the investigated temperature range up to 800 K. The dehydration processes generally followed the first or second order mechanism while the third decomposition steps followed either three-dimensional diffusion or contracting volume mechanism.     

Spectrophotometric determination of iron(III) and total iron by sequential injection analysis technique

A procedure for determination of concentrations of iron(III) and total iron by sequential injection analysis is described. The method is based on the strong blue-colored complexes formed between iron(III) and tiron. The absorbance of the complexes is measured spectrophotometrically at 635 nm. Oxidation of iron(II) and masking of interfering fluoride is simultaneously done by injecting one zone of hydrogen peroxide and one of thorium(IV) between the sample and reagent zones. Concentration of iron(III) and total iron, in the range 0.002–0.026 M, in diluted samples from a pickle bath were determined. The relative standard deviation was 0.4% (n=7). The method was also used in a pilot plant of a zinc process for determination of iron(III) in the range 0.2–3.0 g l⁻¹. The sample throughput is approximately 17 samples per hour, including three repetitive determinations of each sample.     

Cobalt(III) dicarboxylato bis-ethylenediamine nitrates: Preparation and characterization by thermal analysis and other analytical methods

Compounds with the general formulacis ortrans-[Coen ₂ (RCOO)₂]NO₃ were prepared by modifications of known procedures; R was H, CH₃, C₂H₅ or C₃H₇, anden was ethylenediamine. The compounds were characterized by TLC and UV-Vis spectrophotometry, and their thermal behaviour was examined via TG and DTA, and via IR spectra on heated samples.The thermal stabilities are discussed in terms of the strengths of the bonds in the solids [1] and steric hindrance; the thermal decompositions are described with the aid of hypothesized intermediates and IR spectra.Reaction steps are identified and the thermal stability sequence is discussed: thecis compounds are less stable than the correspondingtrans compounds, due to the lower reticulation effect; the sequence of thecis compounds is the reverse of the sequence of carboxylate ion basicity, while the sequence displalyed by thetrans compounds can be interpreted in terms of solid lattice stabilization.

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Zusammenfassung Unter Durchführung einiger Abänderungen des bekannten Verfahrens wurden Verbindungen der allgemeinen Formel conf-Co[en₂(RCOO)₂]NO₃ hergestellt. Der AlkylrestR war H, CH₃, C₂H₅, C₃H₇ unden war Ethylendiamin. Die Verbidungen mitconf=cis odertrans wurden mittels TLC und UV-Spektrophotometrie charakterisiert. Ihr thermisches Verhalten wurdeanhand von TG, DTA und IR-Spektren von erhitzten Proben untersucht. Die thermische Stabilität wurde untersucht und in Abhängigkeit von Bindungsstärke und sterischer Behinderung diskutirt; weiterhin wurden die thermischen Zersetzungen mit Hilfe angenommener Intermediäre und deren IR-Spektren beschrieben. Die Reaktionsschritte wurden identifiziert und eine Stabilitätsreihe aufgestellt und diskutiert: cis-Verbindungen erwiesen sich als instabiler als die entsprechenden trans-Verbindungen, was einem geringeren Vernetzungseffekt zuzuschreiben ist; Die Reihenfolge folgt im Falle voncis dem Reziproken der Carboxylationenbasizität, während die Reihenfolge im Falle vontrans mittels der Gitterstabilisierung erklärt werden kann.

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, -[Coen₂(RCOO)₂]NO₃, R=H, CH₃, C₂H₅, C₃H₇, aen= . - - - . , . . , . : - , , . - -, - .

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This work was carried out with the financial support of the Consiglio Nazionale delle Ricerche (C.N.R.), which also gave a grant to one of us (A.M.G.).     

Physico-chemical studies on the thermal decompositions of iron(III) phthalates

The thermal decompositions of basic salts of iron(III)o-phthalate sesquihydrate, Fe(C₈H₄O₄)(OH)·1.5H₂O, iron(III)m-phthalate trihydrate, Fe(C₈H₄O₄)(OH)·3H₂O, and iron(III)p-phthalate monhydrate, Fe(C₈H₄O₄)(OH)·H₂O, have been investigated from ambient temperature up to 973 K in air using Mössbauer and infrared spectroscopy, derivatography (DTG-DTA-TG) and X-ray diffraction. The thermal decomposition proceeds without reduction to Iron(II) species in the cases of iron(III)o-phthalate and iron(III)p-phthalate, whereas iron(II) species have been detected in the case of basic iron(III)m-phthalate.-Fe₂O₃ is formed as the end-product. Increase in the particle size of the-Fe₂O₃ with increasing decomposition temperature has also been observed.

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Zusammenfassung Die thermische Zersetzung basischer Salze von Eisen(III)-o-phthalat-Sesquihydrat, Fe(C₈H₄O₄)(OH) · 1,5H₂O, Eisen(III)-m-phthalat-Trihydrat, Fe(C₈H₄O₄)(OH)·3H₂O, und Eisen(III)-p-phthalat-Monohydrat, Fe(C₈H₄O₄)(OH)·H₂O, wurden im Temperaturbereich von Raumtemperatur bis 973 K in Luft mittels Mössbauer- und IR-Spektroskopie, Derivatographie (DTG-DTA-TG) und Röntgendiffraktometrie untersucht. Im Gegensatz zu basischem Eisen(III)-m-phthalat erfolgt bei den entsprechendeno- undp-Phthalatverbindungen im Verlaufe der Zersetzung keine Reduktion zu Eisen(II)-Species.-Fe₂O₃ wird als Endprodukt erhalten. Mit steigender Zersetzungstemperatur nimmt die Größe der-Fe₂O₃-Partikel zu.

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c Fe(C₈H₄O₄)(OH)·vH₂O, x = 1.5,3 1, , -, - n-, 973 . , , ë . - n- , m- . -Fe₂O₃. -Fe₂O₃.

     

The study of iron(III) and gold(III) separation by paper chromatography using diisopropyl ether

The influence of experimental conditions on the Chromatographic behavior and separation efficiency of iron(III) and gold(III) in partition paper chromatography was investigated, when solvents containing diisopropyl ether (IPE) were used. The influence of temperature (range investigated from 15 to 50 °C), initial acid concentration (1–11 M HCl), and concentration of active solvent component (0.7–7.1 M IPE, benzene as diluent) on the R_f values were particularly studied. Ascending technique using Whatman No. 1 paper was employed. Considerable influence of temperature was found. The best separation (ΔR_f = 0.26) was achieved with 9 M concentration of hydrochloric acid and 3.6 M (50% volume) concentration of IPE.     

A field-desorption study of thermal stability in potassium pentacyanocobaltates(III)

Field desorption has been applied to research the thermal stability of the compounds K_n[Co(CN)₅X], where X=SO₃ ^2–, CN^–, NO₂ ^–, NO^–, Cl^–, Br^–, I^–, and H₂O. A likely mechanism is proposed for the thermal decomposition. There is a correlation between the tetragonal-distortion parameters and the temperature of onset of destruction for the [Co(CN)₅X]^n– anion.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 1, pp. 111–115, January–February, 1985.     

Catalytic-fluorimetric determination of EDTA and iron(III) by flow injection analysis

Summary In this paper the authors report on several methods for the direct determination of EDTA and indirect determination of iron(III), based on the inhibition effect of EDTA on the catalytic action of copper (II) on the oxidation of 2,2-dipyridyl ketone hydrazone by hydrogen peroxide and on the decrease of this inhibition effect in the presence of Fe(III), respectively. These methods allow the determination of EDTA in the ranges of 0.4–2.0 g · ml^–1 and 0.2–1.0 g · ml^–1 for the normal and reversed FIA modes, respectively, and of 40–240 ng · ml^–1 for Fe(III) by reversed FIA.

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Katalytisch-fluorimetrische Bestimmung von EDTA und Eisen(III) durch FließinjektionsanalyseInhibitionsmethoden

Zusammenfassung Verfahren zur direkten Bestimmung von EDTA sowie zur indirekten Bestimmung von Eisen(III) werden beschrieben. Sie beruhen auf der Inhibitorwirkung von EDTA auf den katalytischen Effekt von Kupfer(II) bei der Oxidation von 2,2-Dipyridylketonhydrazon mit Wasserstoffperoxid bzw. auf der Schwächung dieser Inhibitorwirkung in Gegenwart von Eisen(III). Es ist mit diesen Methoden möglich, EDTA im Bereich von 0,4–2,0 g/ml (normale FIA) bzw. 0,2–1,0 g/ml (umgekehrte FIA) und Eisen im Bereich von 40–240 ng/ml (umgekehrte FIA) zu bestimmen.

     

Voltammetric analysis of iron oxide pigments

Eighteen earthy and four pure synthetic pigments containing alpha-Fe2O3 (hematite), alpha-FeOOH (goethite) and poorly crystalline Fe and Mn oxide species were analyzed by voltammetry of microparticles. Three natural samples were subjected to an interlaboratory test to evaluate the reproducibility of the voltammetric peak potentials and peak shapes. The results confirmed that linear-sweep voltammetry is able to distinguish between poorly crystalline, ferrihydrite-like oxides and well-crystalline hematite and goethite and to detect XRD-amorphous Mn(III,IV) oxides via the peak occurrence. Voltammetry is further able to distinguish between pigments containing well-crystalline goethite (according to its structural features) and hematite (according to its particle size). The microsamples of primers from two baroque paintings were also analyzed by XRD and voltammetry and shown to be analogous to common clayey ochres.     

The study of new zinc(II) aliphatic carboxylate complex compounds by methods of thermal analysis

Four new complex compounds were prepared by the reaction of zinc bromobutyrate and organic ligands. The general formula of the synthetized complex compounds are (2-Brbut)₂ZnL and (4-Brbut)₂ZnL₂nH₂O (but=butyrate, L=theobromine (tbr), theophylline (tph), methyl-3-pyridyl carbamate (mpc), n=0-1). The compounds were characterized by chemical analysis and IR spectroscopy. The thermal behaviour of the zinc(II) complexes was studied by thermal analysis. Thermal decomposition in the case of hydrated compounds starts with the release of water molecules. Then molecules of organic ligands and the bromobutyrate anion are released and decomposed. CH₃CH₂CH=O, CO, CH₂=CHCH=O, CH₂O and ZnBr₂ were found as gaseous products of thermal decomposition during heating up to 700°C. IR, mass spectroscopy, X-ray powder diffraction and chemical analysis were used for the determination of solid and gaseous intermediates and products of the thermal decomposition.This revised version was published online in November 2005 with corrections to the Cover Date.     

Control of electronic structure of a six-coordinate iron(III) porphyrin radical by means of axial ligands

Addition of tert-butylisocyanide (tBuNC) to a CD2Cl2 solution of the bis(perchlorato)(meso-tetramesitylporphyrinato) iron(III) cation radical leads to the formation of the corresponding bis(adduct), [Fe(TMP)(tBuNC)2]2+, whose electronic structure is in sharp contrast to that of the corresponding imidazole(HIm) complex, [Fe(TMP)(HIm)2]2+; the former adopts the S = 0 while the latter exhibits the S = 1 electronic ground state.