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1.
V. V. Shereshovets N. M. Korotaeva Yu. I. Puzin G. V. Leplyanin V. D. Komissarov 《Reaction Kinetics and Catalysis Letters》1990,42(1):39-46
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 Ri.
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. .相似文献
2.
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.
, V2O5–Nb2O5–Ta2O5. . : V2O5 12 /, Nb2O5 14 / Ta2O5 22 /.相似文献
3.
A. A. Kicha A. I. Kalinovskii É. V. Levina P. V. Andriyashchenko 《Chemistry of Natural Compounds》1986,21(6):760-762
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. 相似文献
4.
G. A. Kuznetsova A. Z. Abyshev M. E. Perel'son Yu. N. Sheinker G. Yu. Pek 《Chemistry of Natural Compounds》1968,2(5):252-255
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 相似文献
5.
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·Tb 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.
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·Tb, 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.
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·Tb 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.
. , dT/t=Q. b 4 -2. , . . , b=1, 2 3, b= . . . , , , . .相似文献
6.
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.
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.
, . , , .相似文献
7.
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.
, , - . , .相似文献
8.
V. F. Anufrienko T. M. Yurieva F. S. Hadzhieva T. P. Minyukova S. Yu. Burylin 《Reaction Kinetics and Catalysis Letters》1985,27(1):201-205
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.
, ZnO Cu–O–Cu . Cu2+- , .相似文献
9.
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.
/2 , Si3AlO12H8 Si3AlO12H9. , , , Al.相似文献
10.
ESR data for X(CuO) V2O5·8.3 MoO3 system heated at 400–550 °C indicate the occurrence of a copper state with dZ
2-ground state. Copper ions are orbitally ordered apparently in –Cu2+–O–Cu1+–O–Cu2+-chains.
B X(CuO) V2O5·8,3 MoO3 , 400–550°C dZ 2- . , , –Cu2+–O–Cu1+–O–Cu2+-.相似文献
11.
Zusammenfassung Durch thermodilatometrische und DTA-Untersuchungen wurde das thermische Verhalten von C-Typ-PrO1.50, A-Typ-PrO1.50 und PrO1.833 im Temperaturintervall von Raumtemperatur bis 1200 °C in Luft und Wasserstoff-Atmosphäre untersucht. Die Temperatur des Phasenüberganges C-PrO1.50 A-PrO1.50 wurde zu 790±10 °C gefunden. C-PrO1.50 ist nur unterhalb der Umwandlungstemperatur beständig, A-PrO1.50 im gesamten untersuchten Temperaturbereich. PrO1.833 geht oberhalb von 400 °C, in Luft erhitzt, über mehrere definierte oxidische Zwischenphasen in A-PrO1.50 über.
The thermal behaviour of C-type PrO1.50, A-type PrO1.50 and PrO1.833 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 PrO1.50 A-type PrO1.50 proceeds at 790±10 °C; C-type PrO1.50 is stable only below this temperature, but A-type PrO1.50 in the whole range. Pro1.833 is stable up to 400 °C at atmospheric pressure. When heated further it decomposes stepwise forming several defined intermediate oxide phases.
Résumé On a étudié par thermodilatométrie et ATD le comportement thermique de PrO1.50-type C, PrO1.50-type A, et PrO1.833, 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-PrO1.50/A-PrO1.50. C-PrO1.50 n'est stable qu'au-dessous de la température de conversion, alors que A-PrO1.50 l'est dans tout le domaine de température examiné. PrO1.833 chauffé dans l'air se transforme au-dessus de 400 °C en donnant plusieurs phases intermédiaires d'oxydes définis avant A-PrO1.50.
PrO1.50, PrO1.50 PrO1.833, 20–1200° . PrO1.50 PrO1.50 790±10°; PrO1.50 ; PrO1.50 PrO1.833 400° . , , .相似文献
12.
A. S. Kharitonov A. I. Yartsev E. A. Paukshtis G. S. Litvak E. N. Yurchenko G. I. Panov 《Reaction Kinetics and Catalysis Letters》1988,37(1):7-12
Catalytic properties of V2O5/SiO2 in benzene oxidation by N2O were examined. Sodium additive was shown to affect the catalyst operation stability.
V2O5/SiO2 N2O. .相似文献
13.
S. F. Bureiko N. S. Golubev G. S. Denisov I. Ya. Lange 《Reaction Kinetics and Catalysis Letters》1977,7(2):139-144
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.
1H 2H - CCl4. , CD3OH+H2O相似文献3OD+H2O 3OD+D2O. , - -.
14.
Tomislav P. Živković 《Journal of mathematical chemistry》1992,9(1):55-73
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. 相似文献
15.
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.
The authors wish to thank Prof. E. Pungor for valuable discussions and Mr. M. Arnold for his assistance in performing the experiments. 相似文献
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.
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.
MgNH4PO4·62 - - . , TG GA . , MgNH4PO4·62 . , , . - - .
The authors wish to thank Prof. E. Pungor for valuable discussions and Mr. M. Arnold for his assistance in performing the experiments. 相似文献
16.
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.
We thank Miss B. Sedej for chemical analysis. The work was financed through the Research Community of Slovenia. 相似文献
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.
N2H5AsF6, (N2H5)2ZrF6 (N2H5)2HfF6, - , ., , . , N2H5AsF6 NH4AsF6, (N2H5)2ZrF6 — (NH4)2ZrF6 NH4ZrF5. (N2H5)2HfF6 : (NH4)2HfF6 N2H5HfF5, NH4HfF5. .
We thank Miss B. Sedej for chemical analysis. The work was financed through the Research Community of Slovenia. 相似文献
17.
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.
C1–C4 -. , CO, H2, CH3OH, C2H5OH, C3H7OH, -C4H9OH H2O. .相似文献
18.
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.
, (H2, N2 Ar, He), - Pt-Rh. . . , .相似文献
19.
V. M. Kudenkov L. I. Kiseleva A. V. Mashkina 《Reaction Kinetics and Catalysis Letters》1991,45(2):227-233
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.
, K2WO4/Al2O3 H2S — . , H2S . , — .相似文献
20.
K. Miśkiewicz 《Journal of Thermal Analysis and Calorimetry》1987,32(6):1731-1734
The influence of CSH phase nuclei on calcium chlorosilicate hydration has been studied by means of calorimetry, QXRD, DTA and TG methods.
C=CaO, S=SiO2, H=H2O 相似文献
Zusammenfassung Mittels kalorimetrischen, QXRD-, DTA- und TG-Verfahren wurde der Einfluß von CSH Phasenkörpern auf die Hydratierung von Kalziumchlorosilikat untersucht.
, , .
C=CaO, S=SiO2, H=H2O 相似文献