Oxidative polymerization of durene and diphenyl oxide in the presence of palladium(II) and heteropolyacids

The possibility of obtaining tetramers from durene or diphenyl oxide in the presence of H₅PMo₁₀V₂O₄₀, a reversible oxidant, and palladium acetate as catalyst is demonstrated.

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— H₅PMo₁₀V₂O₄₀ .

     

A mechanistic explanation for the SO2 oxidation rate data of a Cs/V catalyst at high pressures and conversions

A preliminary attempt to modify a molybdena-silica for ethylene homologation was performed by adding copper. Ethylene homologation (3C₂H₄2C₃H₆) was enhanced 2.5 times on copper doped catalyst. Contrary to this, ethylene metathesis (C₂H₄–¹²C₂+C₂H₄–¹³C₂2C₂H₄–¹³C₁) was suppressed in the presence of copper. The selectivity of the homologation to metathesis was increased 7.5 times.

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- , (3C₂H₄2C₃H₆), . 2,5 , (C₂H₄–¹²C₂+C₂H₄–¹³C₂2C₂H₄–¹³C₁) . 7,5 .

     

Possibilities of applying the Piloyan method of determination of decomposition activation energies in the differential thermal analysis of polynitroaromatic compounds and their derivatives

The Piloyan activation energiesE, as well as the initial exotherm temperaturesT _D, are determined for sixN-monoalkyl- and fiveN,N-dialkyl-2,4,6-trinitroanilines. By comparison withR _f-factors, orR _M-functions of paper chromatography, the molecular-structural dependences ofE andT _D are studied for these compounds. Relationships are also found between the termE · T _D ^–1 and theR _M-functions. The effects are discussed of the introduction of the 6-nitro group into the TV-substituted 2,4-dinitroanilines, and of the introduction of the 4-nitro group into the 2,6-dinitro analogues, upon the thermal stabilities of the resulting 2,4,6-trinitroanilines.

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Zusammenfassung Die AktivierungsenergienE nach Piloyan und die Anfangswerte der ExothermenT _D der sechsN-monoalkyl- und fünfN,N-Dialkyl-2,4,6-trinitroaniline wurden bestimmt. Unter Berücksichtigung des Vergleichs mitR _f-Faktoren oderR _M-Funktionen der Papierchromatographie wurden die molekularstrukturellen AbhÄngigkeiten der WerteE undT _D dieser Verbindungen untersucht. ZusammenhÄnge wurden auch zwischen dem AusdruckE · Tw _D ^–1 und denR _M-Funktionen gefunden. Der Einfluss der Einführung der 6-Nitrogruppe in dieN-substituierten 2,4-Dinitroaniline, sowie der Einfluss der Einführung der 4-Nitrogruppe in 2,6-Nitroanaloge auf die ThermostabilitÄt der resultierenden 2,4,6-Trinitroaniline werden erörtert.

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Résumé On a déterminé les énergies d'activation par la méthode de Piloyan ainsi que les températures initialesT _D de l'effet exothermique de sixN-monoalcoyl- et cinqN,N-dialcoyl-2,4,6-trinitroanilines. En se référant aux facteursR _F ou aux valeurs des fonctionsR _M en Chromatographie sur papier, on a étudié la dépendance entre les valeurs deE et deT _D sur les caractéristiques moléculaires-structurales de ces composés.On a également trouvé des rapports entre le termeE · T _D ^–1 et les fonctionsR _M. On discute l'influence de l'introduction du groupe 6-nitro dans les 2,4-dinitroanilinesN-substituées ainsi que l'influence de l'introduction du groupe 4-nitro dans les 2,6-dinitro analogues sur la stabilité thermique des 2,4,6-trinitroanilines qui en résultent.

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N-- N,N--2,4,6- E , T _D. R _f,- R _M — , - E T _D. E.T _D ^–1 R _M-. 6N- 2,4- 4 2,6- 2,4,6- .

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The authors would like to thank Mrs. Anna Colláková for careful DTA measurements, and Dr. Ladislav Smolka for help in the treatment of the measured results with the Wang 600 computer.     

Zum Thermischen Verhalten von Alkylammonium- und Kalium-N-Alkylthiocarbamaten

Zusammenfassung Es wurde das thermische Verhalten von Alkylammonium- und Kalium-N-alkylthiocarbamaten der Zusammensetzung (RNH₃) (RHNCXY) mit X=Y=S oder X= S und Y= 0; R=n-C₃H₇,i-C₃H₇,n-C₄H₉,i-C₄H₉,c-C₆H₁₁ bzw. K(RHNCOS) mit R= CH₃ C₂H₅,n-C₃H₇,i-C₃H₇,n-C₄H₉,i-C₄H₉,c-C₆H₁₁ untersucht. Die Zersetzungsmechanismen zeigen bei allen untersuchten Verbindungen einen ähnlichen Charakter. Im Verlaufe der Thermolyse entstehen symmetrische Dialkylharn- bzw. -thioharnstoffe sowie Aminé, CS₂ (bzw. COS) und H₂S. Während sich die Alkylammoniumthiocarbamate ohne Rückstand zersetzen, verbleibt bei den Kaliummonothiocarbamaten Kaliumsulfat als Rückstand. Für den Prozeß der Harn- bzw. Thioharnstoffbildung während der ersten Abbaustufe der Alkylammoniumthiocarbamate wurden die Aktivierungsenergien berechnet.

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The thermal behaviours of alkylammonium and potassium N-alkylthiocarbamates of general formula (RNH₃) (RHNCXY) (where X= Y= S or X= S and Y= 0; R=n-C₃H₃,i-C₃H₃,n-C₄H₉,i-C₄H₉ orc-C₆H₁₁) and K(RHNCOS) (where R=CH₃, C₂H₅,n-C₃H₇,i-C₃H₇,n-C₄H₉,i-C₄H₉ orc-C₆H₁₁) were investigated. The decomposition mechanisms exhibit a similar character for all studied compounds. In the course of thermolysis symmetric dialkylureas and dialkylthioureas, as well as amines, CS₂ (or COS) and H₂S are formed. The alkylammonium thiocarbamates decompose without any residue, whereas with potassium monothiocarbamates potassium sulfate is left as a residue. For the process of urea and thiourea formation during the first step of decomposition, the activation energies were computed for some compounds.

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Résumé On a étudié le comportement thermique des N-alcoyl-thiocarbamates d'ammonium et de potassium de composition (RNH₃) (RHNCXY), avec X=Y=S ou X=S et Y=O; R=n-C₃H₇,i-C₃H₇,n-C₄H₉,i-C₄H₉,c-C₆H₁₁ ainsi que des composés K(RHNCOS) avec R=CH₃, C₂H₅,n-C₃H₇,i-C₃H₇,n-C₄H₉,i-C₄H₉,c-C₆H₁₁. Les mécanismes de décomposition montrent un caractère similaire pour tous les composés. Au cours de la thermolyse il se forme des dialcoylcarbamides symétriques ou des thiocarbamides ainsi que des amines, CS₂ (ou COS) et H₂S. Alors que les alcoylthiocarbamates d'ammonium se décomposent sans résidu, les monothiocarbamates de potassium donnent du sulfate de potassium comme résidu. On a calculé les énergies d'activation pour la réaction de formation de la carbamide ou de la thiocarbamide pendant la première étape de la décomposition des alcoylthiocarbamates d'ammonium.

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N- (RNH₃) ((RHNCXY), X=.Y=S X=S Y=; R=-₃₇, -₃₇, -C₄H₉, -₄₉, -₆₁₁ K(RHNCOS) c R=₃, ₂₅, -₃₇, -C₃H₇, -₄₉, o-C₄H₉ -₆₁₁. . : , CS₂ ( COS) H₂S. , . , .

     

Study of the adsorption properties of a natural Hungarian mordenite and its ion-exchanged derivatives

The texture and adsorption properties of a natural, Hungarian mordenite were investigated by electron microscopy and BET adsorption measurements. The properties of the ion-exchanged adsorbents were characterized by CO₂ and SO₂ isotherms. The measurements were evaluated on the basis of the pore-filling theory of Dubinin. We have found that at 20°C the H⁺-form of mordenite interacts preferably with CO₂, while on the Na⁺- and Ca²⁺-derivatives stronger adsorption of SO₂ takes place. This fact accounts for their applicability as selective adsorbents.

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, . CO₂ SO₂. . , 20°C H⁺- CO₂, Na⁺- Ca²⁺- SO₂ . .

     

Catalysis of thiophene hydrogenolysis by bimetallic sulfide catalysts of different compositions

The activity of sulfide catalysts M_I/SiO₂, M_I/WS₂, (M_I,W)/SiO₂ and (Ni,M_II)/SiO₂ (M_I is a first row transition metal, and M_II=Nb, Mo, W or Re) in the thiophene hydrogenolysis reaction has been studied. Activities of mono- and bimetallic catalysts are found to change in the same manner depending upon the nature of M_I. The formation of a sulfide bimetallic species (SBMS) is suggested.

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M_I/SiO₂, M_I/WS₂, (M_I,W)/SiO₂ (Ni, M_II)/SiO₂, M_I — , M_II–Nb, Mo, W, Re. - M_I. .

     

Dispersity and reducibility of the molybdenum oxide phase in SiO2, SiO2?Al2O3 and γ-Al2O3 supported molybdena catalysts

XRD, isothermal and temperature-programmed reduction (TPR) experiments were carried out with SiO₂, SiO₂–Al₂O₃ and -Al₂O₃ supported catalysts. Molybdena is in a more disperse state on supports containing more alumina and it is more reducible on SiO₂–Al₂O₃ than on SiO₂ or -Al₂O₃. TPR curves were shown to reflect connections between reduction kinetics and dispersity.

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-, , SiO₂, SiO₂–Al₂O₃ -Al₂O₃. , , SiO₂–Al₂O₃ SiO₂ -Al₂O₃. .

     

Thermoanalytical investigations on the decomposition of double salts

The melting and decomposition behaviour of carnallite was investigated in the closed system under dynamic heating conditions and in the open system under dynamic and quasi-isothermal and quasi-isobaric conditions in the temperature range between 20 and 300°. DTA heating and cooling cycles in the closed system illustrate the incongruent melting of carnallite and the occurrence of different magnesium chloride hydrate phases. The thermal decomposition under quasi-isothermal and quasi-isobaric conditions begins at a pressure of at least 100 kPa from the melt and under reduced pressure from the solid. In any case KCl · MgCl₂ · 2 H₂O is formed which is decomposed to a basic product KMgCl_2.84–2.90(OH_0.10–0.16.

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Zusammenfassung Die Schmelz- und Zersetzungseigenschaften des Carnallits wurden im geschlossenen System unter dynamischen Heizbedingungen und im offenen System under dynamischen und quasi-isothermen und quasi-isobaren Bedingungen im Temperaturbereich von 20 bis 300°C untersucht. DTA Heiz- und Kühlzyklen im geschlossenen System verdeutlichen das inkongruente Schmelzen des Carnallits und das Auftreten verschiedener Magnesiumchlorid-Hydratphasen. Die thermische Zersetzung beginnt unter quasi-isothermen und quasi-isobaren Bedingungen bei einem Druck von mindestens 100 kPa aus der Schmelze und unter verminderten Druck aus der festen Phase. Die Zersetung verläuft stets über KCl · MgCl₂ · 2 H₂O zu einem basischen Produkt KMgCl_2.84–2.90(OH)_0.10–0.16.

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— -, - V 20–300°. . - - 100 , — . KCl · l₂ · 2 ₂, Kgl_2.84–2.90()_0.10–0.16.

     

n-Hexane cracking over heteropoly acids, 1. Treatment of data and temperature dependence of the catalyitc activity of H3PW12O40

The catalytic activity of H₃PW₁₂O₄₀ has been investigated in n-hexane cracking as a function of the reaction temperature. It has been shown that both the polyacid and the anhydride phase formed by its dehydration are active catalysts for this reaction.

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H₃PW₁₂O₄₀ - . , , , , .

     

Study of interaction between trimethyl-substituted silanes and silica surface

Interaction mechanism of (CH₃)₃SiX silanes (X=Br, I, N₃, NCS, NCO, CN, NCNSi(CH₃)₃ and SO₄Si(CH₃)₃ with dehydrated silica surface has been studied by IR spectroscopy. It has been established that (CH₃)₃SiCN, (CH₃)₃SiBr, (CH₃)₃SiI and [(CH₃)₃Si]₂SO₄ can be used as soft silylating agents for endcapping.

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(CH₃)₃SiX (X=Br, I, N₃, NCS, NCO, CN, NCNSi(CH₃)₃, SO₄Si(CH₃)₃) -. , (CH₃)₃SiCN, (CH₃)₃SiBr, (CH₃)₃SiI [(CH₃)₃Si]₂SO₄ .

     

Oxygen diffusion in Me2O?V2O5 melts

The anodic and cathodic polarization of a platinum electrode in K₂O–V₂O₅ melt have been studied. The dissolved oxygen is shown to be ionized. Diffusion coefficients of oxygen in K₂O–V₂O₅ and Na₂O–V₂O₅ melts at various temperatures and K/V ratios are presented.

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K₂O–V₂O₅. , . K₂O–V₂O₅, Na₂O–V₂O₅ K/V.

     

Effect of vanadium content on the character of acidic sites on V2O5/Al2O3 catalysts

By IR spectroscopy and TPD the effect of vanadium content on the relative proportion of strongly acidic sites of V₂O₅/Al₂O₃ catalyst was studied.

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- - V₂O₅/Al₂O₃.

     

Novel catalyst for dihydrogen evolution from water based on rhodium complexes with polyethyleneimine

Catalytic activity of homogeneous and heterogeneous rhodium complexes with polyethyleneimine or ethylenediamine at various Rh:N ratios has been studied in the reaction of water reduction to dihydrogen by V _aq ²⁺ and Cr _aq ²⁺ and the applicability of these catalysts for photocatalytic evolution of H₂ from water is discussed.

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Rh:N V _ap ²⁺ Cr _aq ²⁺ .

     

Effect of supports on the energetics of CO chemisorption on rhodium catalysts

The kinetics of adsorption-desorption processes were measured using Frequency Response Chemisorption for CO on supported Rh catalysts. Measurements on Rh/SiO₂ failed to give a signal, most likely due to the strong natures of the CO sorption on the metal. CO on Rh/TiO₂ measurements indicated the existence of one molecularly adsorbed state. The rate constants for adsorption state were derived.

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- CO Rh . Rh/SiO₂ , - CO . Rh/TiO₂ . .

     

Oxidative coupling of methane over Bi2O3?P2O5?K2O/Sm2O3

Oxidative coupling of methane over Bi₂O₃–P₂O₅–K₂O/Sm₂O₃ takes place giving more C₂H₄ as compared to C₂H₆. Sm₂O₃ supported Bi–P–K is a more active and selective catalyst, than TiO₂, -Al₂O₃, SiO₂ and MgO supported catalysts.

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Bi₂O₃–P₂O₅–K₂O/Sm₂O₃ , . Bi–P–K, Sm₂O₃, , TiO₂, -Al₂O₃, SiO₂, MgO.

     

IR and thermal studies on lithium oxomolybdenum(VI) oxalate

A new molybdenum(VI) complex, Li₂[Mo₂O₆(C₂O₄)] · 2 H₂O (LMO), was prepared and characterized by chemical analysis and IR spectral studies. Its thermal decomposition was studied by using TG and DTA techniques. LMO loses its two moles of water between 75 and 170° to give the anhydrous product, which decomposes in three stages between 240 and 380°. The first two stages occur in the temperature ranges 240–280° and 280–305°, to give intermediates with the tentative compositions Li₆[Mo₆O₁₉(C₂O₄)₂] and Li₆[Mo₆O₂₀(C₂O₄)], respectively. In the third stage, which extends up to 380°, Li₆[Mo₆O₂₀(C₂O₄)] decomposes to give the end-product, Li₂Mo₂O₇.

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Zusammenfassung Ein neuer Molybdän(VI)-Komplex der Formel Li₂[Mo₂O₆(C₂O₄)] · 2 H₂O (LMO) wurde dargestellt und durch chemische Analyse und IR-spektroskopisch charakterisiert. Die thermische Zersetzung dieses Komplexes wurde mittels TG und DTA untersucht. LMO verliert die zwei Wassermoleküle zwischen 75 und 170° unter Bildung des wasserfreien Produktes, das zwischen 240 und 380° in drei Stufen zersetzt wird. Die in den Temperaturbereich von 240–280° und 280–305° verlaufenden ersten zwei Reaktionsschritte ergeben Intermediäre der tentativen Zusammensetzung Li₆[Mo₆O₁₉(C₂O₄)₂] bzw. Li₆[Mo₆O₂₀(C₂O₄)]. In dem sich bis 380° erstreckenden dritten Reaktionsschritt wird Li₆[Mo₆O₂₀(C₂O₄)] unter Bildung des Endproduktes Li₂Mo₂O₇ zersetzt.

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Li₂[MO₂O₆(C₂O₄] · 2 ₂ . . - 70–170° , , 240–380°. 240–280° 280–305° - Li₆[Mo₆O₁₉(C₂O₄)₂] Li₆[Mo₆O₂₀(C₂O₄)]. - 380° Li₂Mo₂O₇.

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The authors are grateful to Prof. S. N. Tandon, Head of the Chemistry Department, for providing the research facilities.     

Thermal decomposition of the solvent-extracted chloro complexes of trivalent gallium,indium and thallium with trioctylamine and trioctylmethylammonium chloride

The complexes of trivalent gallium, indium and thallium with trioctylamine (TOA, R₃N) and trioctylmethylammonium chloride (TOMAC, R₃RNCl) were prepared by drying in vacuo the organic extracts from aqueous solutions containing the chlorides of their metals with TOA and TOMAC in benzene: R₃NHGaCl₄, (R₃NH)₂InCl₅, R₃NHTlCl₄, R₃R'NGaCl₄, R₃R'NInCl₄ and R₃RTlCl₄. The prepared complexes were examined by TG and DTA under an atmosphere of nitrogen, and the products of their thermal decompositions, such as volatile matter and residues, were examined by gas chromatography, X-ay diffraction study and infrared spectrophotometry. It was found that the complexes of these trivalent metals with TOA and TOMAC decompose thermally to the chlorides (GaCl₃, InCl₃ and TlCl) through the cracking of alkyl groups.

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Zusammenfassung Komplexe von dreiwertigem Gallium, Indium und Thallium mit Trioctylamin (TOA, R₃N) und Trioctylmcthylarnmonium-Hydrochlorid (TOMAC, R₃R'NCl) wurden durch Trocknung der benzolischen Extrakte der die Metallchloride mit TOA bzw. TOMAC enthaltenden wässrigen Lösungen im Vakuum dargestellt: R₃NHGaCl₄, (R₃NH)₂InCl₅, R₃NHTlCl₄, R₃R'NGaCl₄, R₃R'NInCl₄ und R₃R'TlCl₄. Die dargestellten Komplexe wurden durch TG und DTA in Stickstoffatmosphäre untersucht. Die Produkte der thermischen Zersetzung, flüchtige Substanzen und Rückstände, wurden gas-chromatographisch, röntgendiffraktometrisch und 1R-spektrophotometrisch untersucht. Es wurde festgestellt, daß die Komplexe dieser dreiwertigen Metalle sich thermisch durch Krackung der Alkylgruppen zu den Chloriden (GaCl₃, InCl₃ und TlCl₃) zersetzen.

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, (, R₃N) ( , R₃RNCl) R₃NHGaCl₄, (R₃NH)₂InCl₅, R₃NHTlCl₄, R₃RNGaCl₄, R₃RNInCl₄ R₃RNTlCl₄ , . , , - . , (GaCl₃, InCl₃ TlCl) c .

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Paper presented at the 1985 World Conference on Thermal Analysis, Bad Hofgastein, Austria.

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We wish to thank the Research and Development Laboratory, Swiss Aluminium Ltd., Neuhausen, Switzerland, for the gift of gallium metal, and the Koei Chemical Co. Ltd. for samples of TOA and TOMAC.     

Effect of heating rate and γ-Radiation on the structure of As4SexTe6−x Glasses

The phenomena accompanying the temperature-induced structural changes in five As₄Se_xTe_6–x glasses, withx=1 tox=5, were examined and are discussed. Differential thermal analysis traces of each glass composition at different heating rates from 2 to 50 deg/min were obtained and interpreted. The effect of the Se/Te ratio on the crystallization behaviour is discussed. It is interesting to note that the compositional dependence of the overall behaviour of the crystallization activation energy (E) seems to be similar to that of both the melting point (T_m) and the thermal conductivity () for the investigated glasses. Created structural defects due to gamma-irradiation have some effects on the crystallization process.

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Zusammenfassung Die die temperaturbedingten strukturellen Veränderungen von 5 Glasern der allgemeinen Zusammensetzung As₄Se_xTe_6–x (x=1–5) begleitenden Phänomene wurden untersucht und diskutiert. Die von jedem Glas bei unterschiedlichen Aufheizgeschwindigkeiten zwischen 2 und 50 Grad pro Minute erhaltenen DTA-Kurven werden interpretiert. Der Effekt des Se/Te-Verhältnisses auf das Kristallisationsverhalten wird diskutiert. Von Interesse ist, daß die Abhängigkeit der Aktivierungsenergie (E) der Kristallisation von der Zusammensetzung der des Schmelzpunktes (Tm) und der Wärmeleitfähigkeit (*) der untersuchten Gläser ähnelt. Durch y-Bestrahlung hervorgerufene strukturelle Defekte haben einen gewissen Einfluß auf den Kristallisationsprozeß.

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, As₄Se_x,Te_6–x, c x=1–5. ( 2 50°/) . Se/Te . , , (T _m ) (). , -, .

     

On the mechanism of chlorobenzene hydrolysis over Cu promoted lanthanum phosphate

The reaction mechanism of chlorobenzene hydrolysis to produce phenol over Cu promoted lanthanum phosphate has been studied taking into account a parallel reaction through which benzene is formed. There is a competition for the adsorption sites between the reactants and the reaction products.

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, , , . .

     

Reactivity of the carbonaceous surface overlayer on supported platinum catalysts studied by high temperature pyrolysis gas chromatography

The reactivity of the carbonaceous surface overlayer formed on Pt/Al₂O₃ catalysts in n-hexane dehydrocyclization has been studied by high temperature Pyrolysis Gas Chromatography. This method can be used to characterize surface carbon overlayers formed on different catalysts in the course of hydrocarbon reactions.

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, Pt/Al₂O₃ -, . , .