Reaction of triphenyl phosphite ozonide with thioacetals

Kinetic regularities in the reaction of triphenyl phosphite ozonide with several thioacetals in CH₂Cl₂ solution at –15°C have been studied. The consumption rate of ozonides is described by the kinetic equation W=k₀[(C₆H₅O)₃P·O₃]+k₁[(C₆H₅O)₃P·O₃][R₁R₂C(SR₃)₂] Rate constants k₀ and k₁ for the thioacetals: (CH₃H₇S)₂CH₂, (C₆H₅S)₂CH₂, (C₆H₅CH₂S)₂CH, (n=C₁₂H₂₅–S)₂CH₂, (C₃H₇S)₂C(H)CH₃, (C₃H₇S)₂C(H)C₆H₅, (C₃H₇S)₂C(CH₃)C₆H₅ and (C₃H₇S)₂C(H)C₁₀H₉, increases with increasing the electron-donating power of subtituents R_i.

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CH₂Cl₂ –15°C. : W=k₀[(C₆H₅O)₃P·O₃]+k₁[(C₆H₅O)₃P·O₃][R₁R₂C(SR₃)₂] k₀ k₁ (C₃H₇S)₂CH₂, (C₆H₅S)₂CH₂, (C₆H₅CH₂S)₂CH₂, (n-C₁₂H₂₅S)₂CH₂, (C₃H₇S)₂C(H)CH₃, (C₃H₇S)₂C(H)C₆H₅, (C₃H₇S)₂C(CH₃)C₆H₅, (C₃H₇S)₂C(H)C₁₀H₉. .

     

Comparative study of the catalytic properties of V2O5, Nb2O5 and Ta2O5 in the oxidation of methanol to formaldehyde

The selectivity of the oxides under consideration to the oxidation of methanol to formaldehyde is shown to increase in the sequence V₂O₅–Nb₂O₅–Ta₂O₅. The same sequence corresponds to the decrease in specific activity. The activation energy of the reaction is 12 kcal/mol for V₂O₅, 14 kcal/mol for Nb₂O₅ and 22 kcal/mol for Ta₂O₅.

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, V₂O₅–Nb₂O₅–Ta₂O₅. . : V₂O₅ 12 /, Nb₂O₅ 14 / Ta₂O₅ 22 /.

     

Culcitoside C1 from the starfishCulcita novaeguineae andLinckia guildingi

By repeated chromatography on Polikhrom-1, silica gel, and Florisil, ethanolic extracts of two species of starfish,Culcita novaeguineae andLinckia guildingi, have yielded the new steroid glycoside culcitoside C₁ (I): 5-cholestan-3,4,6,8,15,24-hexaol 24-O-[2,4-di-O-methyl--D-xylopyranosyl-(12)--L-arabinofuranoside], C₃₉H₆₈O₁₄, mp 245–248°C, []_D -35.8°, c 0.6; methanol). Its structure was shown by the results of acid hydrolysis, acetylation and methylation, and¹H and¹³C NMR spectroscopy.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 801–804, November–December, 1985.     

A new coumarin, pranferol, from the roots ofPrangos ferulacea

Summary A new coumarin, pranferol C₁₆H₁₆O₅, has been isolated from the roots ofPrangos ferulacea (L.) Lindl.The structure 5-(2-hydroxy-3-methylbutoxy)furo-2,3:7,6-coumarin has been proposed for pranferol.Khimiya Prirodnykh Soedinenii, Vol. 9, No. 5, pp. 310–315, 1966     

Der Einfluss der Temperaturführung auf die Kinetische Auswertung Nichtisothermer Reaktionen

Zusammenfassung Das Problem der rationellen Lösung des Zeitintegrals stand bei der kinetischen Auswertung nichtisothermer Prozesse häufig zur Diskussion. Nun werden für lineare und nichtlineare Aufheizung gemäß dT/dt=Q·T_b mitb von 4 bis –2 Auswerteverfahren vorgestellt, die in jedem Fall eine vollständige Korrektur derjenigen kinetischen Parameter gestatteten, die durch linearisierte Auswertung erhalten worden sind. Diese Methode der vollständigen Exponentialintegrale zeigt, daß eine klare Abstufung nach dem Typ der Aufheizung besteht. Die notwendigen Korrekturen fürb=1, 2 und 3 sind kleiner als fürb=0 d.h. für lineare Aufheizung. Die vier Korrekturtabellen sind für Verfahren der kinetischen Analyse anwendbar, denen ein Aktivierungsansatz nach Arrhenius bzw. Eyring zugrunde liegt. Die Realisierung nichtlinearer Aufheizprogramme wird empfohlen.

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The problems of rational solution of the time integral in kinetical evaluation of nonisothermal processes have often been discussed. Evaluation procedures are now presented for linear and nonlinear heating according to dT/dt=Q·T^b, withb between 4, and –2. In every case a complete correction of the kinetical parameters is possible if they are obtained by linearized plotting. This method of complete exponential integrals shows a clear graduation with the type of heating function. The corrections necessary forb=1, 2 and 3 are less than those forb=0, i.e. linear heating. Four tables of correction values are applicable to all procedures of kinetical analysis which are based on activation parameters from the Arrhenius or Eyring equations. Nonlinear heating programmes are recommended.

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Résumé On a souvent discuté les problèmes soulevés par la solution rationnelle de l'intégrale du temps dans l'évaluation cinétique des processus non-isothermes. On présente ici des méthodes d'évaluation dans le cas de chauffages linéaire et non-linéaire, selon dT/dt=Q·T^b avecb entre 4 et –2. Une correction complète des paramètres cinétiques est possible dans tous les cas, si ceux-ci ont été obtenus par des fonctions linéarisées. Cette méthode d'intégration complète des exponentielles montre une graduation nette selon le type de la fonction du chauffage. La correction nécessaire pourb=1, 2 et 3 est inférieure à celle pourb=0, c'est-à-dire pour le chauffage linéaire. Quatre tables de correction basées sur les paramètres d'activation des équations d'Arrhenius et respectivement d'Eyring peuvent être appliquées à tous les procédés de l'analyse cinétique. On recommande de réaliser des programmes de chauffage non-linéaires.

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. , dT/t=Q. ^b 4 -2. , . . , b=1, 2 3, b= . . . , , , . .

     

Eine Thermowaage für den Unterricht

Zusammenfassung Eine Thermowaage, mit der gleichzeitig die Masse und die Temperatur in einer Probe gemessen werden können, wurde für Lehrzwecke entwickelt. Am Beispiel der Verdunstung von Aceton, der Entwässerung von Kupfersulfat-pentahydrat, der Zersetzung von Magnesiumoxalat-dihydrat und der Pyrolyse von Weichholz werden ihre TG-Kurven diskutiert.

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A thermobalance for teaching purposes was constructed which is able to measure simultaneously mass and temperature in a sample. The effectiveness of the device is discussed by the TGA curves of the evaporation of acetone, the dehydration of copper sulphate pentahydrate, the decomposition of magnesium oxalate dihydrate, and the pyrolysis of wood.

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, . , , .

     

Effect of quantization of molecular rotations on the rate of capture in the ion-linear dipole system

The version of transition state theory that accounts for quantization of the rotational energy of a dipole gives ion-dipole capture rate constants in good agreement with the statistical adiabatic channel model and, in the region , gives results more accurate than those obtained by numerical trajectory calculations.

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, , - . , .

     

Spectroscopic studies of the state of Cu2+ ions in Cu?Zn?Al oxide catalysts

ESR and electronic spectroscopy have reveled that in low-temperature ZnO the copper ions form Cu–O–Cu type cluster structures with highly covalent bonds and strong exchange interaction between the ions. The nearer environment of the Cu²⁺ ions is an octahedron with distortion towards square planar coordination.

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, ZnO Cu–O–Cu . Cu²⁺- , .

     

Quantum chemical study of the physical characteristics of the hydroxy groups of zeolites, III

The CNDO/2 method was applied to calculate the electronic structure of HY zeolite using cluster models Si₃AlO₁₂H ₈ ^– and Si₃AlO₁₂H₉. It has been shown that the probability of occurrence of H on a particular type of oxygen as well as the other physical characteristics of zeolite depend on both the type of oxygen and the position of the Al atom.

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/2 , Si₃AlO₁₂H₈ Si₃AlO₁₂H₉. , , , Al.

     

State of copper in massive Cu?V?Mo oxide systems

ESR data for X(CuO) V₂O₅·8.3 MoO₃ system heated at 400–550 °C indicate the occurrence of a copper state with d_Z ²-ground state. Copper ions are orbitally ordered apparently in –Cu²⁺–O–Cu¹⁺–O–Cu²⁺-chains.

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B X(CuO) V₂O₅·8,3 MoO₃ , 400–550°C d_Z ²- . , , –Cu²⁺–O–Cu¹⁺–O–Cu²⁺-.

     

Der Phasenübergang C-Typ-PrO1.50 → A-Typ-PrO1.50

Zusammenfassung Durch thermodilatometrische und DTA-Untersuchungen wurde das thermische Verhalten von C-Typ-PrO_1.50, A-Typ-PrO_1.50 und PrO_1.833 im Temperaturintervall von Raumtemperatur bis 1200 °C in Luft und Wasserstoff-Atmosphäre untersucht. Die Temperatur des Phasenüberganges C-PrO_1.50 A-PrO_1.50 wurde zu 790±10 °C gefunden. C-PrO_1.50 ist nur unterhalb der Umwandlungstemperatur beständig, A-PrO_1.50 im gesamten untersuchten Temperaturbereich. PrO_1.833 geht oberhalb von 400 °C, in Luft erhitzt, über mehrere definierte oxidische Zwischenphasen in A-PrO_1.50 über.

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The thermal behaviour of C-type PrO_1.50, A-type PrO_1.50 and PrO_1.833 was investigated by thermodilatometric and DTA measurements in the temperature range from 20 to 1200 °C in air and in a hydrogen atmosphere. The phase transition C-type PrO_1.50 A-type PrO_1.50 proceeds at 790±10 °C; C-type PrO_1.50 is stable only below this temperature, but A-type PrO_1.50 in the whole range. Pro_1.833 is stable up to 400 °C at atmospheric pressure. When heated further it decomposes stepwise forming several defined intermediate oxide phases.

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Résumé On a étudié par thermodilatométrie et ATD le comportement thermique de PrO_1.50-type C, PrO_1.50-type A, et PrO_1.833, dans le domaine de température allant jusqu'à 1200 °C, dans l'air et en atmosphère d'hydrogène. On a trouvé 790±10° comme température de la transition de phase C-PrO_1.50/A-PrO_1.50. C-PrO_1.50 n'est stable qu'au-dessous de la température de conversion, alors que A-PrO_1.50 l'est dans tout le domaine de température examiné. PrO_1.833 chauffé dans l'air se transforme au-dessus de 400 °C en donnant plusieurs phases intermédiaires d'oxydes définis avant A-PrO_1.50.

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PrO_1.50, PrO_1.50 PrO_1.833, 20–1200° . PrO_1.50 PrO_1.50 790±10°; PrO_1.50 ; PrO_1.50 PrO_1.833 400° . , , .

     

Acid properties and stability of operation of vanadium catalysts in benzene oxidation to phenol

Catalytic properties of V₂O₅/SiO₂ in benzene oxidation by N₂O were examined. Sodium additive was shown to affect the catalyst operation stability.

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V₂O₅/SiO₂ N₂O. .

     

Kinetic isotope effect in proton exchange processes between methanol and water in inert solvents

The kinetic isotope effect in proton exchange between methanol and water in CCl₄ solution was studied by¹H and²H NMR and kinetic IR spectroscopy. The exchange rate increases in the series CD₃OH+H₂O3OD+H₂O3OD+D₂O. It has been concluded that the limiting step of the reaction involves the formation of an H-bonded cyclic intermediate.

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¹H ²H - CCl₄. , CD₃OH+H₂O3OD+H₂O3OD+D₂O. , - -.

     

Eigenvalues of the real generalized eigenvalue equation perturbed by a low-rank perturbation

The low-rank perturbation (LRP) method solves the perturbed eigenvalue equation (B +V) _k = _k (C +P) _k , where the eigenvalues and the eigenstates of the related unperturbed eigenvalue equationB _i = _i C _i are known. The method is designed for arbitraryn-by-n matricesB, V, C, andP, with the only restriction that the eigenstates _i of the unperturbed equation should form a complete set. We consider here a real LRP problem where all matrices are Hermitian, and where in addition matricesC and (C +P) are positive definite. These conditions guarantee reality of the eigenvalues _k and _i . In the original formulation of the LRP method, each eigenvalue _k is obtained iteratively, starting from some approximate eigenvalue _k . If this approximate eigenvalue is not well chosen, the iteration may sometimes diverge. It is shown that in the case of a real LRP problem, this danger can be completely eliminated. If the rank of the generalized perturbation {V, P} is small with respect ton, then one can easily bracket and hence locate to any desirable accuracy the eigenvalues _k (k = 1, ...,n) of the perturbed equation. The calculation of alln eigenvalues requiresO(² n ²) operations. In addition, if the perturbation (V, P) is local with the localizabilityl p, then onlyO(² n) operations are required for a derivation of a single eigenvalue.     

TG and EGA investigations of the decomposition of magnesium ammonium phosphate hexahydrate by means of the Derivatograph under conventional and quasiisothermal — Quasi-isobaric conditions

An investigation was made of the thermal decomposition of MgNH₄PO₄ · 6H₂O under conventional and under quasi-isothermal—quasi-isobaric conditions. The experiments were carried out with a Derivatograph-suitable for simultaneous TG and EGA examinations. It was found that the thermal decomposition of MgNH₄PO₄·6H₂O consists of three, more or less overlapping partial processes. First 5 moles, then 1 mole of water of crystallization depart, and finally, strictly simultaneously and in an inseparable way, the departure of the ammonia and water of constitution takes place. The three processes can be separated best under quasi-isothermal and quasi-isobaric conditions.

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Zusammenfassung Die Autoren untersuchten die thermische Zersetzung von MgNH₄PO₄·6H₂O unter konventionellen und quasi isothermischen — quasi isobaren Bedingungen. Die Versuche wurden mit einem zur TG- und EGA-Analyse geeigneten Derivatograph-Typ durchgeführt. Die Autoren fanden, daß die thermische Zersetzung von MgNH₄PO₄·6H₂O aus drei mehr oder weniger überlappenden Teilvorgängen besteht. Zuerst werden 5, dann 1 Mol Kristallwasser entfernt, das Konstitutionswasser und Ammoniak werden streng simultan und von einander untrennbar entfernt. Die drei Vorgänge können am besten unter quasi isothermischen und quasi isobaren Bedingungen von einander getrennt werden.

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Résumé Les auteurs ont étudié la décomposition thermique de MgNH₄PO₄·6H₂O dans les conditions conventionelles ainsi que dans des conditions presque isothermes et presque isobares. On a effectué les expériences à l'aide d'un Derivatograph qui se prête aux études simultanées par TG et AGE. Dans les conditions conventionnelles, la décomposition thermique de MgNH₄PO₄·6H₂O s'effectue en trois processus élémentaires qui se recouvrent plus ou moins. Le départ de 5 puis d'une molécule d'eau de cristallisation est suivi de celui d'ammoniac et d'eau de constitution, celui-ci étant strictement simultané et indissociable. Ces trois processus peuvent être mieux séparés si l'on opère dans des conditions voisines du régime isotherme et isobare.

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MgNH₄PO₄·6₂ - - . , TG GA . , MgNH₄PO₄·6₂ . , , . - - .

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The authors wish to thank Prof. E. Pungor for valuable discussions and Mr. M. Arnold for his assistance in performing the experiments.     

Thermal behaviour of some new hydrazinium fluorometallates

Three new hydrazinium(1+) fluoro complexes, N₂H₅AsF₆, (N₂H₅)₂ZrF₆ and (N₂H₅)₂HfF₆, were prepared and characterized by means of chemical analysis, IR and Raman spectroscopy and X-ray powder diffraction. Study of their thermal behaviour via TG, DTG and DTA measurements showed that they decompose in stages; the decomposition of N₂H₅AsF₆ proceeded in two steps, through the intermediate NH₄AsF₆; (N₂H₅)₂ZrF₆. Decomposed in three steps, through (NH₄)₂ZrF₆ and NH₄ZrF₅. The thermal decomposition of (N₂H₅)₂HfF₆ is more complex; in the first step (NH₄)₂HfF₆ with some N₂H₅HfF₅ was obtained, and in the second NH₄HfF₅. The intermediates were identified by means of chemical analysis and vibrational spectroscopy.

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Zusammenfassung Die Hydrazinium(1+)-fluorokomplexe N₂H₅AsF₆, (N₂H₅)₂ZrF₆ und (N₂H₅)₂HfF₆ wurden dargestellt und durch chemische Analyse, IR- und Ramanspektren sowie Röntgenbeugungsdiagramme charakterisiert. Die Untersuchung ihres thermischen Verhaltens durch simultane TG-DTG-DTA-Messungen zeigte, dass sie sich schrittweise zersetzen: N₂H₅AsF₆ zersetzt sich in 2 Stufen mit NH₄AsF₆ als Zwischenprodukt; (N₂H₅)₂ZrF₆ zersetzt sich in 3 Stufen über (NH₄)₂ZrF₆ und NH₄ZrF₅. Die thermische Zersetzung von (N₂H₅)₂HfF₆ ist komplizierter, der erste Schritt liefert (NH₄)₂HfF₆ mit wenig N₂H₅HfF₅, der zweite NH₄HfF₅. Die Zwischenprodukte wurden durch chemische Analyse und Schwingungsspektroskopie identifiziert.

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N₂H₅AsF₆, (N₂H₅)₂ZrF₆ (N₂H₅)₂HfF₆, - , ., , . , N₂H₅AsF₆ NH₄AsF₆, (N₂H₅)₂ZrF₆ — (NH₄)₂ZrF₆ NH₄ZrF₅. (N₂H₅)₂HfF₆ : (NH₄)₂HfF₆ N₂H₅HfF₅, NH₄HfF₅. .

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We thank Miss B. Sedej for chemical analysis. The work was financed through the Research Community of Slovenia.     

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. .

     

Influence of diluting gases on the oxygen-hydrogen reaction on a Pt-Rh catalyst

The influence of changes in the diluting gas (H₂, N₂, Ar, He) on the rate of the catalytic oxygen-hydrogen reaction on a Pt-Rh catalyst is described. The experiments were carried out by measuring the warm-up of the catalyst by the reaction heat and calculating the amount of heat evolved. The existence of the influence of the diluting gas on the rate of reaction is established. This result is discussed on the basis of energy dissipation processes from bonds formed in the reaction.

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, (H₂, N₂ Ar, He), - Pt-Rh. . . , .

     

Interaction of methanol with hydrogen sulfide in the presence of K2WO4/Al2O3

Kinetic data show that in the presence of K₂WO₄/Al₂O₃, methanethiol is largely produced by the reaction of H₂S with metanol and partly with dimethyl ether. Dimethyl sulfide is formed during the interaction of methanethiol with methanol, of H₂S with dimethyl ether and as a result of methanethiol disproportionation. Methane and carbon oxides are the decomposition products of methanethiol and dimethyl sulfide and of methanol and dimethyl ether, respectively.

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, K₂WO₄/Al₂O₃ H₂S — . , H₂S . , — .

     

The influence of CSH phase nuclei on Ca3SiO4Cl2 hydration

The influence of CSH phase nuclei on calcium chlorosilicate hydration has been studied by means of calorimetry, QXRD, DTA and TG methods.

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Zusammenfassung Mittels kalorimetrischen, QXRD-, DTA- und TG-Verfahren wurde der Einfluß von CSH Phasenkörpern auf die Hydratierung von Kalziumchlorosilikat untersucht.

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, , .

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C=CaO, S=SiO₂, H=H₂O