Thermodynamics of 2,2′,2′'-terpyridinecopper(II) complexes in aqueous solution

Summary The thermodynamic quantities relative to the protonation and the complexation of 2,2,2'-terpyridine with copper(II) ion have been determined at 25° and I=0.1 mol dm^–3 (NaNO₃). The G data was obtained by potentiometric measurements; a copper selective electrode was employed for the study of the complexation equilibria. The H values have been determined by direct calorimetry.The hydrolytic species, existing at pH>6 and their relative G and H values have also been obtained.From the thermodynamic data the importance of enthalpy and entropy terms in stabilizing the complexes is assessed.Moreover some considerations on the chelating effect are reported.Presented in part at 2 Congresso Nazionale di Chimica Analitica, Catania (1977).     

Nitric oxide disproportionation on chabazite tuff

The catalytic activity of a chabazite tuff in the reaction 4NON₂O+N₂O₃ was investigated in flow conditions at temperatures between –78 °C and +85 °C. The Ca or Na enriched samples are much more active than the natural tuff; the steady state NO conversion increases with decreasing temperature.

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4NON₂O+N₂O₃ –78°C +85°C. , Ca Na , ; NO .

     

Thermal synthesis of non-stoichiometric Bi5.8PO11.2

The formation of the compound Bi_5.8PO_11.2 from 2.4 Bi₂O₃+BiPO₄ was investigated by means of DTA, simultaneous DTA—high-temperature thermomicroscopy, and X-ray diffraction. Solid-state reactions begin above 700 °C, followed by intermediate local melting and exothermic reactions. These are coupled with the intermediate formation of-Bi₂O₃, Bi₁₂P_0.8O₂₀ (both with sillenite structure) and Bi₄P₂O₁₁. The reaction is completed upon congruent melting of Bi_5.8PO_11.2 at 955 °C.The formation of Bi_5.8PO_11.2 from 2.9 Bi₂O₃+NH₄H₂PO₄ begins after melting of NH₄H₂PO₄ at around 200 °C, and is similarly completed at 955 °C.

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Zusammenfassung Die Bildung der Verbindung Bi_5.8PO_11.2 aus 2,4 Bi₂O₃+BiPO₄ wurde mittels DTA, simultaner DTA-Hochtemperatur-Thermomikroskopie und Röntgenbeugung untersucht. Die Umsetzung beginnt als Festkörperreaktion oberhalb 700 °C, gefolgt durch intermediäres örtliches Schmelzen und exotherme Reaktionen. Dabei werden als Zwischenprodukte-Bi₂O₃, Bi₁₂P_0.8O₂₀ (beide mit Sillenit-Struktur) sowie Bi₄P₂O₁₁ nachgewiesen. Die Umsetzung wird erst beim kongruenten Schmelzen des Bi_5,8PO_11,2 bei 955 °C beendet. Die Bildung von Bi_5,8PO_11,2 aus 2,9 Bi₂O₃ + NH₄H₂PO₄ beginnt nach dem Schmelzen des NH₄H₂PO₄ bei ca. 200 °C und geht ebenfalls erst bei 955 °C zu Ende.

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, Bi_5.8PO_11.2 2,4 Bi₂O₃ BiPO₄. 700° , — -Bi₂O₃, Bi₁₂P_0,8O₂₀ ( ) Bi₄P₂O₁₁. Bi_5,8PO_11,2 955°. 2,9 Bi₂O₃ NH₄H₂PO₄ 200° 955°.

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Thanks are due to Mrs. K. Norouzi for performing most of the DTA measurements, and to Mr. P. Höfner for the recording and discussions of the X-ray diffractograms.     

Mono and dinuclear cationic rhodium(I) and iridium(I) complexes with sulphur donor and group Vb ligands

Summary Rhodium(I) and iridium(I) mixed complexes of the formulae [M(diolefin)LL]ClO₄, [M(diolefin)L₂L]ClO₄, [(diolefin)LIr(-L)₂IrL(diolefin)](ClO₄)₂, [(diolefin)LM(-L-L)ML'(diolefin)](ClO₄)₂, [(diolefin)Rh{-(L-L)}₂Rh(PPh₃)₂](ClO₄)₂ and [(diolefin)LIr{-(L-L)}₂IrL (diolefin)](C1O₄)₂, (L=monodentate sulphur ligand, L-L=bidentate sulphur ligand, L=group Vb ligand; M=Rh, diolefin=1,5-cyclooctadiene (COD) or 2,5-norbornadiene (NBD); M=Ir, diolefin=COD) are described.Author to whom all correspondence should be directed.     

Cross Aldolization Between Benzaldehyde and n-Heptaldehyde to α-Pentylcinnamaldehyde Overcalcined mg-al Hydrotalcites

Calcined Mg-Al hydrotalcites (CHT) with various Mg/Al atomic ratios were prepared and characterized by XRD, BET and TPD of carbon dioxide. The CHT catalysts were utilized for the synthesis of -pentylcinnamaldehyde (-P_c) from benzaldehyde and n-heptaldehyde in a stirred batch autoclave reactor. An increase of Mg/Al atomic ratio of CHT samples results in the apparent enhancement of catalyst basicity with concomitant decrease of surface areas. Both the catalytic activity and the -P_c selectivity increase with the catalyst basicity and the reaction temperature.     

Comparative study of measured and critically evaluated resonance integral to thermal cross-section ratios. Part II

The present paper deals with the experimental determination and the critical evaluation of Q_o, the ratio of the resonance integral (I_o) to the 2200 m.s^–1 cross-section (_o) for 57 analytically interesting (n, ) reactions, including a revision and updating of formerly published results for 13 isotopes. Full account is given for deviations from the ideal epithermal neutron flux distribution. The Budapest-Gent cooperative determinations, yielding parallel but independent results, lead to recommended Q_o-values with an average uncertainty as low as 3%. Finally, with the aid of independently evaluated or measured _o-data, a list of recommended I_o-values is given.     

Synthesis of γ-Fe2O3 by thermal decomposition of FeC4H4O6·2.5H2O

Iron(II) tartrate two and a half hydrate (FeC₄H₄O₆·2.5H₂O) was prepared and its thermal dehydration and decomposition were studied with a simultaneous thermal analyser (TG/DTA/DTG) under atmospheres of static air, dynamic dry nitrogen and dynamic air. This study was supplemented with the two-probe d.c. electrical conductivity technique under the same atmospheres. Under all the above atmospheres, the thermal dehydration was found to be a two-step process. However, the thermal decomposition process was quite complicated, involving the formation of various metastable intermediates, including-Fe₂O₃. The final product of decomposition under all atmosphere was-Fe₂O₃.Studies on the physical properties of-Fe₂O₃ were also undertaken.

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Zusammenfassung Es wurde Eisen(II)-tartrathydrat (FeC₄H₄O₆ · 2,5H₂O) hergestellt und seine thermische Dehydratation bzw. Zersetzung in statischer Luftatmosphäre bzw. im Stickstoff- und Luftstrom mittels eines Simultanthermoanalysators (TG/DTA/DTG) untersucht, ergänzt durch Untersuchungen nach dem Gleichstromleitfähigkeitsverfahren in den gleichen Atmosphären. Die thermische Dehydratation wurde in jedem Falle als zweistufig befunden. Der thermische Zersetzungsprozeß ist jedoch wegen der Bildung verschiedener metastabiler Zwischenprodukte, z. B.-Fe₂O₃, recht kompliziert. Das Endprodukt der Zersetzung war in allen Fällen-Fe₂O₃. Weiterhin wurden die physikalischen Eigenschaften von-Fe₂O₃ untersucht.

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, FeC₄H₄O₆ · 2,5₂. . , . , y-Fe₂O₃. -Fe₂O₃. -Fe₂O₃.

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Now deceased.

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Financial assistance for this work was given by Grants-in-aid (Defence Ministry), Govt. of India. One of the authors (A.V.R.) is grateful to the Head, Dept. of Chemistry, Sardar Patel University, for his interest and encouragement.     

Kinetic study of the thermal dehydration of layered [Ni2Al(OH)6]2SO4.nH 2O

The kinetics of thermal dehydration of [Ni₂Al(OH)₆]₂SO₄.nH₂O has been studied through the analysis of isothermal weight loss data. The results obtained seem to indicate that the process is governed by a diffusion mechanism up to an value which is dependent on the temperature. An explanation is provided for this behaviour on the basis of the structural properties of the compound and the nature of the water loss.

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Zusammenfassung Die Kinetik der thermischen Dehydratisierung von [Ni₂Al(OH)₆]₂SO₄.nH₂O wurde mittels isothermer TG untersucht. Die Ergebnisse scheinen darauf hinzudeuten, daß der Prozeß bis zu einem von der Temperatur abhängigen -Wert von einem Diffusionsmechanismus bestimmt wird. Für dieses Verhalten wird basierend auf den strukturellen Eigenschaften der Verbindung und der Natur der Wasserabgabe eine Erklärung gegeben.

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, [Ni₂Al(OH)₆]₂SO₄.nH₂O. , , . , .

     

Analysis of the heat capacities of group IV chalcogenides using debye temperatures

The low temperature heat capacities of 13 group IV chalcogenides are examined. The heat capacity of crystals with largely isotropic structure (GeTe, SnSe, SnTe, PbS, PbSe, PbTe) can be represented within ±3% by a three-dimensional Debye function ( ₃=205, 230, 175, 225, 150 and 130, respectively). The heat capacity of crystals with anisotropic structures (GeS, GeSe, SnS, GeS₂ and SnS₂) could only be represented by pairs of two-dimensional Debye functions for the longitudinal and transverse lattice vibrations (error ±0.5 to 3%; ₂ (l)=505, 345, 400, 705, 480 and 570, respectively, and ₂ (t)=200, 185, 160, 175, 100 and 265, respectively).Since the two-dimensional Debye function has not been tabulated in detail, we offer in the appendix a five place table of it. Raman and infrared data support this analysis.

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Zusammenfassung Die Wärmekapazität bei niedrigen Temperaturen wurde für 13 Chalcogenide der Gruppe IV untersucht. Die Wärmekapazität der Kristalle von hauptsächlich istotroper Struktur (GeTe, SnSe, SnTe, PbS, PbSe, PbTe) kann innerhalb von ±3% durch eine. dreidimensionale Debye-Funktion dargestellt werden ( ₃=205, 230, 175, 225, 150 bzw. 130). Die Wärmekapazität von Kristallen anisotroper Struktur (GeS, GeSe, SnS, GeS₂, GeSe₂ und SnS₂) konnte für longitudinale und transversale Gittervibrationen nur durch Paare zweidimensionaler Debye-Funktionen dargestellt werden (Fehler: ±0,5 bis 3%; ₂ (l)=505, 345 400, 705, 480 bzw. 570 und ₂(t)=200, 185, 160, 175, 100 bzw. 265).Da die zweidimensionale Debye-Funktion nicht in allen Einzelheiten tabellarisiert worden ist, wird im Anhang eine fünfstellige Tafel dafür gegeben. Raman- und Infrarot-Angaben bestätigen diese Analyse.

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Résumé On a examiné les capacités calorifiques à basses températures de 13 chalcogénure du groupe IV. Les capacités calorifiques des cristaux de structures principalement isotrope (GeTe, SnSe, SnTe, PbS, PbSe, PbTe) peuvent être représentées à ±3%, par une fonction Debye à trois dimensions ( ₃=205, 230, 175, 225, 150 et 130 respectivement). Les capacités calorifiques des cristaux à structures anisotropes (GeS, GeSe, SnS, GeS₂, GeSe₂ et SnS₂) ne peuvent être représentées que par des paires de fonctions Debye à deux dimensions, pour les vibrations du réseau longitudinales et transversales (erreur de ±0,5 à 3%; ₂(l)=505, 345, 400, 705, 480 et 570, et ₂,(t)=200,185, 160, 175, 100 et 265).Comme il n'existe pas de tableaux détaillés pour la fonction Debye à deux dimensions les auteurs donnent en appendice un tableau à cinq positions. Des données Raman et infrarouges sont fournies à l'appui de cette analyse.

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13 IV. (GeTe, SnSe, SnTe, PbS, PbSe, PbTe) ±3% ( ₃=205, 230, 175, 225, 150 130, ). (GeS, GeSe, SnS, GeS₂, GeSe₂, SnS₂) ( ±0.5 3%; ₂ (.)=505, 345, 400, 705, 480 570 , ₂ (.)=200, 185, 160, 175, 100 265). , . .

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The authors would like to acknowledge the help of Professor H. H. Hollinger and Professor M. S. Krishnamoorty with the solution of the two-dimensional Debye function. The authors would also like to acknowledge the support of this work in part by the National Aeronautics and Space Administration and by the National Science Foundation, Polymer Programs, Contract No. DMR 78-15279.     

Support and mixing effect of an Fe2O3 catalyst for oxidative dehydrogenation of 1-butene

The support and mixing effects of Fe₂O₃ for the activity of 1-butene oxidative dehydrogenation were examined. Alumina and titania which were able to catalyze the isomerization of butene via an allyl intermediate, stimulated remarkably the formation of butadiene from butene when they were used as support or mixing component of Fe₂O₃ catalyst. Otherwise Fe₂O₃ supported on SO ₄ ^2– ion containing Al₂O₃ or TiO₂–Al₂O₃, which catalyze the isomerization via a cationic intermediate, is almost inactive for the formation of butadiene.

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Fe₂O₃ 1-. , , , Fe₂O₃. , Fe₂O₃, Al₂O₃, SO ₄ ^–2 , TiO₂–Al₂O₃, , .

     

Synthesen von Heterocyclen, 117. Mitt.: Eine Synthese von β-Lactamen

Zusammenfassung Aus Mono-und Dihalogen-essigsäuren bilden sich mitSchiff-schen Basen in Dimethylformamid (DMF) und POCl₃ (bzw. POBr₃) über labile Addukte -Lactame. Analog reagieren -Chlor-und -Brom-propionsäure.

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The reaction of -chloro and -bromo acetic or propionic acids withSchiff bases inDMF in the presence of POCl₃ or POBr₃ yields -lactames via unstable adducts.

     

Zinc oxide as a formose catalyst

Zinc oxide heterogeneously catalyzes formaldehyde condensation to a complex mixture of formose sugars. The reaction proceeds at pH 5.5 and unwanted Cannizzaro side reaction does not occur. The catalyzed reaction is exceptionally slow. At 100°C and 1.00 M ZnO, 0.61 M HCHO starting concentration, the induction period lasts 70 h and 90% conversion does not occur until 92 h. Either addition of D-glucose co-catalyst or reduction in the starting ratio of HCHO to ZnO eliminates the induction period.

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. pH=5,5 . . 100°C ZnO 1,00 M HCHO 0,61 M 70 , 90%- 92 . -D-, HCHO ZnO

     

On the Role of Surface Forces in Contact Interaction between Elastic Sphere and Hard Surface

The works preformed earlier were reviewed briefly, and the new problem of the contact interaction between the elastic sphere and hard surface was formulated. The solution of a problem to the generalized surface force and its contact and noncontact components was obtained. The specific case of the obtained solution, when the separation = 0, was considered. The existence of two states of contact interaction between the elastic sphere and hard plane was revealed at = 0: (i) the stable state, at contact with the neck of radius a ₁= , where Ris the sphere radius, = (1 – )/(E), Eis the modulus of elasticity of the sphere, is its Poisson's coefficient, and () is the specific energy of adhesion of the surfaces at the lowest possible separation between these surfaces; and (ii) the unstable (metastable) state, at contact with radius a ₂= 0, i.e., at the point contact between the sphere and the plane. In this case, however, the stable contact with the neck at 0 when the modulus of elasticity E , i.e., at the interaction between the hard sphere and hard plane, is also degenerated into the point contact. It was shown that at the point contact, the contact component F _s ^"of the generalized surface force F _svanishes, whereas the noncontact component F _s ^"acquires the value F _s ^"= F _s= 2R() equal to the force of adhesion.     

Alcohol formation from synthesis gas: A thermodynamic study

A thermodynamic study is presented for the simultaneous synthesis of C₁–C₄ alcohols from synthesis gas. The equilibrium composition was calculated for the gaseous mixture containing Co, H₂, CH₃OH, C₂H₅OH, C₃H₇OH, n-C₄H₉OH and H₂O. Operating industrial conditions were specifically considered.

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C₁–C₄ -. , CO, H₂, CH₃OH, C₂H₅OH, C₃H₇OH, -C₄H₉OH H₂O. .

     

Comparative kinetic and thermodynamic study on the chlorination of V2O5 with CCl4, COCl2 and Cl2

The chlorination kinetics of pure vanadia was studied via isothermal thermogravimetric measurements, with CCl₄, CoCl₂ and Cl₂ as chlorinating agents. At temperatures where chemical control was predominant, apparent activation energies of 77, 48 and 126 kJ: mol^–1 were obtained for chlorination by CCl₄, COCl₄ and Cl₂, respectively. For interpretation of the conversion vs. time curves in the whole conversion range, a non-uniform particle size distribution was assumed, where the reacting solid phase was considered to be composed of thin plates of different thicknesses. With this model, a fairly good correspondence was obtained between the measured and calculated kinetic curves. Selected thermodynamic calculation data on the V₂O₅ + CCl₄, V₂O₅ + COCl₂ and V₂O₅ + Cl₂ systems are presented.

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Zusammenfassung Mittels isothermen Thermogravimetriemessungen wurde die Kinetik der Chlorierung von reinem Vanadiumoxid mit CCl₄, COCl₂ und Cl₂ als Chlorierungsmittel untersucht. Bei Temperaturen mit vorherrschender chemischer Kontrolle wurde für die Chlorierung mit CCl₄, COCl₂ bzw. Cl₂ Bruttoaktivierungsenergien von 77, 48 bzw. 126 kJ/mol erhalten. Zur Interpretation der Konversion-Zeit-Diagramme im gesamten Conversionsbereich wurde eine nichteinheitliche Teilchengrösseverteilung angenommen, namentlich den Bestand der reagierenden Festphase aus dünnen Plättchen unterschiedlicher Dicke. Mit diesem Modell konnte eine recht gute Übereinstimmung zwischen errechneten und ermittelten kinetischen Kurven erhalten werden. Einige thermodynamische Rechenbeispiele für die Systeme V₂O₅ + CCl₄, V₂O₅ + COCl₂ und V₂O₅+Cl₂ wurden gegeben.

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, l₄, l₂ l₂. , l₄, l₂ l₂, 77, 48 126 ·^–1. — , . , . - . V₂O₅+CCl₄, V₂O₅+COCl₂ V₂O₅+Cl₂.

     

The thermal decomposition of phosphorus iodides

The thermal decomposition of crystalline PI₃ and P₂I₄ in nitrogen and oxygen is reported. The oxidation of PI₃ leads mainly to the formation of phosphorus pentoxide and iodine together with P_xI polymeric species as a minor product. The decomposition of the polymeric species P₃I₂O₆ in oxygen and nitrogen follows a two-stage route which precludes its involvement in the oxidation of P₂I₄.

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Zusammenfassung Es wurde die thermische Zersetzung von kristallinem PI₃ und P₂I₄ in Stickstoff und Sauerstoff untersucht. Die Oxydation von PI₃ führt zur Bildung von Phosphorpentoxyd und Jod mit wenig Polymeren der Zusammensetzung P_xI. Die Zersetzung der Polymeren P₃I₂O₄ in Sauerstoff und Stickstoff erfolgt in zwei Stufen, die eine Beteiligung in der Oxydation von P₂I₄ ausschließen.

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Résumé On décrit la décomposition thermique, dans l'azote et dans l'oxygène, de PI₃ et de P₂I₂ cristallins. L'oxydation de PI₃ conduit principalement à la formation d'iode et de pentoxyde de phosphore, avec de petites quantités de P_xI de type polymère. La décomposition de l'espèce polymère P₃I₂O₆, dans l'oxygène et dans l'azote, s'effectue suivant un processus en deux étapes excluant sa participation à l'oxydation de P₂I₄.

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I₃ P₂I₄ . I₃, , , — — _xI . ₃I₂₆ , ₂I₄.

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The author is indebted to Mrs. I. M. Walker for practical assistance with the thermoanalysis studies.     

A study of thermal preparation of iron (III) pigments by means of thermal analysis methods

The decomposition of hydronium jarosite occurs in two temperature ranges: first a loss of 8 moles of H₂O from 2 moles of jarosite, then in the second step one mole of H₂O and 4 moles of SO₃ are simultaneously evolved. Fe(OH)(SO₄)₂ and Fe₂O(SO₄)₂ are assumed intermediates. During the thermal treatment of Na or K jarosits, only Fe2(SO₄)₃ appears as intermediate. The decomposition temperatures are significantly influenced by the type of crucible used (determination of partial pressure of gaseous decomposition products). The particle size distribution of the starting jarosite has no effect upon the temperature of the decomposition steps and of the reaction with ZnO.The results of TG measurements were evaluated via calculations of the steps of the experimental activation energies for these partial decomposition jarosites and for their reaction with ZnO.

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Zusammenfassung Die Zersetzung von Hydronium-jarosit verläuft in zwei Stufen: (1) Abgabe von 8 Mol Wasser, (2) simultane Abspaltung von 1 Mol Wasser + 4 Mol SO₃/2 Mol Jarosit. Als Zwischenprodukte werden Fe(OH)(SO₄) und Fe₂O(SO₄)₂ vermutet. Bei der thermischen Zersetzung von Na- und K-Jarosit tritt nur Fe₂(SO₄)₃ als Zwischenprodukt auf.Die Zersetzungstemperaturen werden durch die Tiegelform erheblich beeinflusst (über den Partialdruck der gasförmigen Zersetzungsprodukte). Die Teilchengrössenverteilung des Ausgangs-Jarosits hat keinen Einfluss auf die Temperaturen der Zersetzungsschritte des Jarosits und der Reaktion mit ZnO. Aus den Ergebnissen der TG-Messungen werden experimentelle Aktivierungsenergien für die Zersetzungsreaktionen der Jarosite und ihre Umsetzung mit ZnO berechnet.

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- . 8 , — 4 . Fe(OH)SO₄ Fe₂O(SO₄)₂. Fe₂(SO₄)₃. , , . . .

     

Acetonation of L-sorbose catalyzed by heteropoly acids

Acetonation of L-sorbose—a step of ascorbic acid synthesis—takes place in acetone to yield 85% of diacetone-L-sorbose in the presence of heteropoly acids H₃PW₁₂O₄₀ and H₄SiW₁₂O₄₀ (0.1–0.35%) as catalysts.

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L-— L- — -L- 85% 0.1–0.35% H₃PW₁₂O₄₀ H₄SiW₁₂O₄₀ .

     

Structure of vanadium phosphate anion in solutions from17O,51V and31P NMR data

¹⁷O,⁵¹V and³¹P NMR studies indicate that the anion structure of sodium vanadophosphate in an aqueous solution is close to that in crystals of the (CN₃H₆)₈HPV₁₄O₄₂ 7H₂O salt.

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¹⁷O,⁵¹V,³¹P , (CN₃H₆)₈HPV₁₄O₄₂ 7H₂O.