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1.
V. E. Agabekov N. L. Budeiko E. T. Denisov N. I. Mitskevich 《Reaction Kinetics and Catalysis Letters》1977,7(4):437-443
A competition method (R.+O2RO
2
.
, R.+XHRH+X.) is proposed to measure the relative rate constants for the interaction of alkyl radicals with different organic compounds. Partial (per C–H bond) rate constants have been determined for the reaction of undecyl radicals with cumene, ethylbenzene and toluene.
(R.+O2RO 2 . , R.+XHRH+X.), . ( C–H ) , .相似文献
2.
G. T. Bhandage J. A. K. Tareen B. Basavalingu 《Journal of Thermal Analysis and Calorimetry》1987,32(6):1823-1831
The standard thermodynamic properties of M(OH)2 (M=Mn, Ni and Cd) solid phases have been retrieved using a graphical approach based on the already reportedP vs. T curves obtained from hydrothermal studies of MO-H2O systems. This approach avoids the use of heat capacity effects. The values retrieved by this modified approach are in good agreement with the calorimetric values.
The authors express their grateful thanks to Prof. V. Venkatachalapathy, Director of the Minerological Institute, for his encouragement during the course of this work. 相似文献
Zusammenfassung Basierend auf unlängst beschriebenen, aus hydrothermischen Untersuchungen von MO-H2O Systemen gewonnenenp-T Kurven wurden mittels einer graphischen Näherung die thermodynamischen Standardeigenschaften von M(OH)2 Festphasen (M=Mn, Ni und Cd) bestimmt. Dieses Verfahren umgeht den Gebrauch von Wärmekapazitätseffekten. Die durch dieses modifizierte Verfahren erhaltenen Werte stehen in guter Übereinstimmung mit den kalorimetrischen Werten.
- , O-H2O, M(OH)2, M=, . . .
The authors express their grateful thanks to Prof. V. Venkatachalapathy, Director of the Minerological Institute, for his encouragement during the course of this work. 相似文献
3.
G. L. Elizarova L. G. Matvienko N. V. Lozhkina V. N. Parmon 《Reaction Kinetics and Catalysis Letters》1983,22(1-2):49-53
Some peculiarities of reduction of one-electron oxidants, Ru(bpy)
3
3+
and Ru(bpy)2(py)
2
3+
, in the absence of catalysts (when oxidation of the oxidant's ligands occurs) and in their presence (when also oxidation of water to dioxygen occurs) are discussed. Both oxidation reactions are thought to have a common intermediate.
Ru(bpy) 3 3+ Ru(bpy)2(py) 2 3+ ( -) ( ). , .相似文献
4.
TheC
v
toC
p
conversion for solid linear macromolecules via the Nernst-Lindemann equationC
p
-C
v
=A
0,C
p
2
T/Tm is discussed on hand of data for 10 crystals and seven glasses. An average value ofA
0=(5.11±2.41) · 10–3 mol K J–1 was calculated if the mole is assumed to refer to heavy atoms only. ThisA
0 is numerically equal to the original Nernst—Lindemann constant.
Support by the National Science Foundation, Polymers Program (Grant No. DMR 83-17097) is gratefully acknowledged. 相似文献
Zusammenfassung An Hand von sich auf 10 Kristalle und 7 Gläser beziehenden Daten wird die Umrechnung vonC v -inC p -Werte für feste lineare Makromoleküle mittels der Nernst-Lindemann-GleichungC p -C v =A 0 C p 2 T/T m diskutiert. Ein Durchschnittswert vonA 0=(5.11±2.41) · 10–3 mol K J–1 wurde unter der Annahme berechnet, daß sich das Mol nur auf schwere Atome bezieht. DieserA 0-Wert ist numerisch gleich der ursprünglichen Nerns-Lindemann-Konstanten.
10 , - C v C p , —C p –C v = 0 p 2 / . , , 0 (5.11±2.41) · 10–3 · –1. 0 — .
Support by the National Science Foundation, Polymers Program (Grant No. DMR 83-17097) is gratefully acknowledged. 相似文献
5.
Kinetics of oxidation of formaldehyde, formic acid and formate anion by peroxomonosulfate (PMS) were studied. Formaldehyde is oxidized both by HSO
5
–
and SO
5
2–
, whereas formic acid and formate ion are oxidized by SO
5
2–
alone. The kinetic results show that the formaldehyde is 103 times more reactive than formic acid, which in turn reacts 102 times faster than formate anion. Mechanisms are discussed in terms of the kinetic results.
, . HSO 5 – , SO 5 2– , SO 5 2– . , . 103 , , , , . 102 , . .相似文献
6.
L. I. Bulgakova V. L. Kuznetsov Yu. I. Yermakov L. A. Sazonov 《Reaction Kinetics and Catalysis Letters》1983,22(3-4):259-264
Molecular isotope exchange of CO with14CO for Rh6(CO)16/Sn(II)–SiO2, Rh6(CO)16/Al2O3, Rh(I)(CO)2/Al2O3, Rh4(CO)12/Al2O3 carbonyl complexes of rhodium has been studied. Estimates of the activation energies and a mechanism of the CO exchange are suggested.
, (Rh6(CO)16/Sn(II)–SiO2, Rh6(CO)16/Al2O3, RhI(CO)2/Al2O3, Rh4(CO)12/Al2O3), 14CO. CO .相似文献
7.
The error in purity determinations by differential scanning calorimetry has been studied on two different kinds of systems, metallic and organic, the latter with different types of impurities added. The organic systems have been corrected for solid-solubility error by a nuclear magnetic resonance technique.The impurities chosen for the organic systems were either quite dissimilar to the matrix or similar enough to render solid solution probable. This solid solution leads to deviations from the equation used for dynamic purity determinations. The nuclear magnetic resonance determination of the solidus establishes the proper starting temperature for area summation on a DSC curve.
On leave from The Institute for Physical Chemistry, Polish Academy of Science, Warsaw, Poland.
The authors are grateful to the National Science Foundation for its support through Research Grant CHE 76-08765, and to S. E. Walter for assistance with some calculations. 相似文献
Zusammenfassung Der Fehler in Reinheitsbestimmungen mittels Differential-Scanning-kalorimetrie wurde an zwei verschiedenartigen Systemen untersucht, metallisch und organisch, wobei zu letzteren verschiedentliche Verunreinigungen zugefügt wurden. Der durch Feststoff-Feststofflöslichkeit verursachte Fehler in den organischen Systemen wurde mittels einer kernmagnetischen Resonanzmethode korrigiert.Die für die organischen Systeme gewählten Verunreinigungen waren entweder sehr verschieden von der Matrix, oder aber genügend ähnlich, um feste Lösungen wahrscheinlich zu machen. Diese festen Lösungen führen zu Abweichungen von der für dynamische Reinheitsbestimmungen angewendeten Gleichung. Die Bestimmung der kernmagnetischen Resonanz des Feststoffs ermöglicht die Bestimmung der richtigen Anfangstemperatur für die Flächen-summierung auf der DSC-Kurve.
: . . . , , , , . , . -.
On leave from The Institute for Physical Chemistry, Polish Academy of Science, Warsaw, Poland.
The authors are grateful to the National Science Foundation for its support through Research Grant CHE 76-08765, and to S. E. Walter for assistance with some calculations. 相似文献
8.
L. N. Krasnopyorov N. K. Serdyuk V. P. Strunin V. N. Panfilov 《Reaction Kinetics and Catalysis Letters》1977,7(3):321-326
The rate constants for Br(2P1/2) and Br(2P3/2) atoms in the reaction Br+CH3FHBr+CH2F in photobromination of CH3F have been determined. Their ratio is 10–(2.6±0.5) exp(10100±1000/RT) in the temperature range of 60–200 °C.
Br(2P1/2) Br(2P3/2) Br+CH3FHBr+CH2F CH3F. 60–200 °C 10–(2,6±0,5) exp (10100±1000/RT).相似文献
9.
I. Gorzkowska M. Maciejewski R. Rudnicki 《Journal of Thermal Analysis and Calorimetry》1988,33(3):983-990
The thermal decompositoon of calcium carbonate mixed with calcium fluoride was examined by means of simultaneous TG, DTG and DTA. The temperature range of CaCO3 decomposition shifted to higher temperatures as a result of CaCO3-CaF2 eutectic formation. The temperature of melting of this eutectic was in the temperature range of CaCO3 decomposition, and therefore all factors which increase the partial pressure of CO2 (such as the thickness of the sample layer, the shape of the crucible, the heating rate, etc.) influence the amount of the liquid phase. The DTA curves can be regarded as the sum of three endothermic effects occurring almost simultaneously: decomposition of CaCO3 in the solid phase, melting of the eutectic, and decomposition of CaCO3 present in the liquid phase.
Zusammenfassung Die thermische Zersetzung von Calciumcarbonat-Calciumfluorid-Mischungen wurde durch simultane TG-DTG-DTA untersucht. Der Bereich der CaCO3-Zersetzung wird infolge der Bildung des CaCO3-CaF2-Eutektikums zu höheren Temperaturen verschoben. Die Schmelztemperatur dieses Eutektikums liegt im Temperaturbereich der CaCO3-Zersetzung, deshalb haben alle Faktoren, die den Partialdruck des CO2 beeinflussen (Schichtdicke der Probe, Tiegelgeometrie, Aufheizgeschwindigkeit usw.) auch Einfluss auf die Menge der entstehenden flüssigen Phase. Die DTA-Kurven entstehen durch Überlagerung von 3 endothermen Effekten, die fast gleichzeitig ablaufen: Zersetzung von CaCO3 in fester Phase, Schmelzen des Eutektikums, Zersetzung von CaCO3 in flüssiger Phase.
, . , CaCO3-CaF2. , 2 ( , , .) . : , , .相似文献
10.
Z. A. Mansurov A. A. Matafonov A. A. Konnov G. I. Ksandopulo 《Reaction Kinetics and Catalysis Letters》1990,41(2):265-270
Damping and stable oscillation of free radical concentrations in butane oxidation have been found and studied experimentally by using a differential thermocouple. It has been established that maximum oscillations of radical concentrations slightly precede temperature maxima.
і і і і і . . .相似文献
11.
The double malonates of gadolinium, terbium and holmium with sodium, of the type Na5Ln(C3H2O4)4.7.5H2O, have been studied by means of thermal analysis. A mechanism of thermal dehydration and decomposition has been proposed on the basis of the results obtained.
Part II. Communicated 相似文献
Zusammenfassung Doppelmalonate von Gadolinium, Terbium und Holmium mit Natrium des Typs Na5Ln(C3H2O4)4.7,5 H2O wurden mittels thermischer Analyse untersucht. Für die thermische Dehydratisierung und Zersetzung wird ein auf den erhaltenen Ergebnissen basierender Mechanismus vorgeschlagen.
, Na5Ln(C3H2O4)4.7.5H2O. .
Part II. Communicated 相似文献
12.
M. Senba D. J. Arseneau J. J. Pan M. Shelley D. G. Fleming 《Journal of Radioanalytical and Nuclear Chemistry》1995,190(2):493-503
Muonium (Mu=++e-) is the bound state of a positive muon and an electron. Since the positive muon has a mass about 1/9 of the proton, Mu can be regarded as an ultra light isotope of hydrogen with unusually large mass ratios (MuHDT=1/9123). The muon spin rotation technique (SR) relies on the facts that (1) the muon produced in pion decay, + + + , is 100% spin polarized and (2) the positron from muon decay is emitted preferentially along the instantaneous muon spin direction at the time of the muon decay.In transverse field SR (TF-SR), the precession of the muon spin in muonium substituted radicals is directly observed by detecting decay positrons time differentially. From observed radical frequencies, the hyperfine coupling constants (A
) of C2H4Mu, C2D4Mu,13C2H4Mu, C2F4Mu, and C2H3FMu are determined. In the longitudinal field avoided level crossing (LF-ALC) technique, one observes the resonant loss of the muon spin polarization caused by the crossing of hyperfine levels at particular magnetic fields. The LF-ALC method together with the information onA
obtained from TF-SR allows one to determine the magnitude and sign of the nuclear hyperfine constants at - and -positions. Results are compared with hydrogen substituted ethyl-radicals and isotope effects are discussed. 相似文献
13.
The title compound, [cis-Co(en)2(NO2)2](NO2) (1), crystallizes in the polar, nonenantiomorphic, monoclinic space group, Cc, with lattice constants:a=9.198(2) Å,b=12.444(2),c=9.963(3), and=96.76(2)°;V=1132.39 Å3 andd(calc;Z=4) =1.860 g cm–3. Thus, with NO2– as the counteranion, [cis-Co(en)2(NO2)2] crystallizes in a heterochiral lattice containing racemic pairs of cations. A total of 2699 data were collected over the range of 4°270°; of these, 1859 (independent and withI3(I)) were used in the structural analysis. Data were corrected for absorption (=15.465 cm–1) and the relative transmission coefficients ranged from 0.9934 to 0.7112. Refinement was carried out for both lattice polarities and the finalR(F) andR
w
(F) residuals were, respectively, 0.0242 and 0.0202 for (–––) and 0.0264 and 0.0243 for (+++). Thus, the former was selected as correct for our specimen.Unlike all previous X-ray diffraction studies of the structural properties of the cation [cis-Co(en)2(NO2)2]+, which are found to have a pair of oppositely configured en rings [i.e., () or ()], we find that in1 the cations are in the lowest energy conformation and configuration; i.e., () or (). We attribute this change in configuration to the formation of strong interionic hydrogen bonds between nitrite anion oxygens and the axial—NH2 hydrogens, which markedly weaken the intermolecular and intramolecular hydrogen bonds between ligand—NO2 oxygens and the hydrogens of those same amine moieties. Thus, the nitrite anions behave exactly as nitrate anions, except that the hydrogen bonds found here are stronger than those formed by the latter. This is as expected since the negative charge is delocalized over two, instead of three, oxygens. 相似文献
14.
A metal-supported catalyst (Ru/SiO2) has been prepared using the sol-gel technique. The structural properties of the solid obtained are compared to those of a conventionally impregnated catalyst.
(Ru/SiO2) -. .相似文献
15.
Seven complex compounds exhibiting the compositions Ni(en)3Ni(CN)4·H2O (I), Ni(en)3Ni(CN)4 (II),-Ni(en)2Ni(CN)4 (III), Ni(en)Ni(CN)4·2H2O (IV), Ni(en)Ni(CN)4 (V), Ni(en)2Ni(CN)4 · 2.5H2O (VI) and-Ni(en)2Ni(CN)4 (VII) were prepared from the system Ni-en-[Ni(CN)4]2–-H2O. These compounds were examined by the methods of infrared spectroscopy, X-ray powder diffractometry, UV-VIS reflectance spectroscopy, and also by the measurement of magnetic moments. The thermal stability, the stoichiometry of thermal decomposition and the mutual transformations were investigated with a derivatograph. The reactions proceeding according to the following schemes were observed if the system was heated to appropriate temperature: (I)(II)(III)(V)(IV) and (VI)(VII)(III)(V)(IV) Process (VII)(III) represents isomerization. The reversibility of the process (V)(IV) is due to the high hygroscopicity of the anhydrous complex. The changes in structure in the course of the individual processes are discussed.
Zusammenfassung Aus einem System Ni-en-[Ni(CN)4]2–-H2O wurden sieben Komplexe der Formeln Ni(en)3Ni(CN)4·H2O (I), Ni(en)3Ni(CN)4 (II),-Ni(en)2Ni(CN)4 (III), Ni(en)Ni(CN)4·2H2O (IV), Ni(en)Ni(CN)4 (V), Ni(en)2Ni(CN)4 · 2.5H2O (VI) und-Ni(en)2Ni(CN)4 (VII) hergestellt. Diese Verbindungen wurden mittels IR-Spektroskopie, Röntgenpulverdiffraktometrie, UV-Reflexionsspektroskopie und durch Messungen des magnetischen Momentes untersucht. Die Wärmestabilität, die Stöchiometrie des thermischen Zerfalles und die gegenseitigen Umwandlungen wurden mittels eines Derivatographen untersucht. Wird das System auf geeignete Temperaturen erhitzt, kann der Reaktionsverlauf durch folgendes Schema dargestellt werden: (I)(II)(III)(V)(IV) und (VI)(VII)(III)(V)(IV).Der Prozeß (VII)(III) verkörpert eine Isomerisierung. Die Umkehrbarkeit von Prozeß (V)(IV) ist auf die ausgeprägten Hygroskopieeigenschaften des wasserfreien Komplexes zurückzuführen. Es werden die im Ablaufe der einzelnen Prozesse vorgehenden Strukturveränderungen besprochen.
Ni- -[No(N)]2 -2 Ni(en)3Ni(CN)4 · 2 (I), Ni(en)3Ni(CN)4 (II),-Ni(en)2Ni(CN)4 (III), Ni(en)Ni(CN)4-2H2O (IV), Ni(en)Ni(CN)4 (V), Ni(en)2Ni(CN)4 · 2,5H2O (VI) -Ni(en)2Ni(CN)4 (VII). , , - , . , . (I)(II)(III)(V)(IV) (VI)(VII)(III)(V)(IV). (VII)(III) . (V)(IV) . .相似文献
16.
Contact potential differences between electrodes of Pt, Au and Ta of different surface finishing were measured by the dynamic condenser method in propylene and oxygen. Propylene is irreversibly adsorbed, thus changing the work function. This renders the electrodes unsuitable as standard electrodes for work function measurements on catalysts in the atmosphere of hydrocarbons, but they may be used in adsorption studies on oxygen.
Pt, Au Ta . , , . , .相似文献
17.
I. V. Kozhevnikov 《Reaction Kinetics and Catalysis Letters》1976,5(4):415-419
Furan and its 2-substituted derivatives (substituents: –CH3, –CHO, –COOCH3, –COOC2H5, –CH(OOCCH3)2) have been shown to react with palladium acetate in solution at 90–130°C giving the corresponding bifuran derivatives in high yields. The following order of activities has been obtained: –H, –CH3, –CHO>–COOCH3, –COOC2H5, –CH(OOCCH3)2>–COOH, which corresponds to the substituent effect in electrophilic substitution in heteroaromatic compounds.
, 2- (: –CH3, –CHO, –COOCH3, –COOC2H5, –CH(OOCCH3)2) 90–130° . : –H, –CH3, –CHO>–COOCH3, –COOC2H5, –CH(OOCCH3)2>–COOH, .相似文献
18.
A series of fifteen complexes of the type [Fe(RRNCS2)3] with symmetric (R=R=n- C6H13, n-C8H17, CH2–CH=;CH2, C6H5, C6H11 and C6H5CH2), unsymmetric (R = CH3; R = n-C4H9, C6H11, C6H5 and R = C2H5; R = n-C4H9, C6H11, C6H5 and i-C3H7) and ring substituents (RNR=pyrrolidyl and piperidyl) have been synthesized and their magnetic moments and Mössbauer spectra recorded from room temperature (RT) to liquid nitrogen temperature (LNT). Room temperature Mössbauer spectra of all the complexes exhibit an asymmetric doublet, which could be resolved into two doublets, each corresponding to low and high spin states in equilibrium. The crystal structure of tris(N, N-diallyldithiocarbamato)iron(III) shows it to be monoclinic with trigonally distorted octahedral geometry and space group C2/c. Fe–S stretching vibrations in the far i.r. region also show equilibria, HS LS. Depending on the nature of the alkyl group substituent, variable temperature magnetic moment and Mössbauer spectral studies, all the complexes may be divided into three groups; high spin complexes exhibiting spin-crossover (6A1g 2T2g), high spin complexes exhibiting spin transition (6A1g 4T1g) and intermediate spin complexes showing spin transition (4A1g 2T2g). On the basis of areas of the two doublets corresponding to high and low spin states, their percent contributions were calculated. Furthermore, magnetic moments of the equilibrium mixture calculated on the basis of respective areas compare well with the experimentally determined eff values. EQ values for both high and low spin states show linear decrease with increasing temperature. 相似文献
19.
N. S. Gnep M. L. Martin de Armando M. Guisnet 《Reaction Kinetics and Catalysis Letters》1980,13(3):183-189
Toluene transformation was investigated on a fluorided alumina and a protonic mordenite under hydrogen (0.8, 12 bar) and under nitrogen (12 bar). Hydrogen pressure considerably improves the catalytic stability of H-mordenite by inhibiting the formation of coke. Moreover, hydrogen eliminates part of the coke deposited by reaction under nitrogen, and regenerates the activity of the mordenite. On the contrary, hydrogen has no effect in the case of fluorided alumina. The particular behavior of the mordenite is attributed to its very strong acidity.
(0,8, 12 ) (12 ). -, . , , , . , - . .相似文献
20.
Katalin Kovács-Hadady Éva Balázs Ilona T. Kiss Sándor Bohátka Gyula Szö'or 《Journal of Thermal Analysis and Calorimetry》1989,35(5):1499-1505
A cross-linked dextranomer, which is used as a wound drying and cleansing powder (CrupodexR), has been investigated by several thermoanalytical methods. First the TG, DTG and DTA characteristics were studied and compared with those of another product (DebrisanR), marketed earlier. The TG curves were also used for the examination of water uptake and the drying process. The traces of organic solvents (mainly ethanol) remaining from the manufacturing process were studied with a quadrupole mass-spectrometer coupled to a derivatograph. From the results of these experiments, several conclusions were drawn about the mechanism of water and solvent uptake.
Zusammenfassung CrupodexR-Puder, ein vernetztes Dextranomer zum Trocknen und Säubern von Wunden, wurde mittels einiger thermoanalytischer Methoden untersucht. Zuerst wurden die TG, DTG und DTA Charakteristiken betrachtet und mit denen eines schon früher auf den markt gekommenen Produktes (DebrisanR) verglichen. Die TG-Kurven wurden auch zur Untersuchung der Wasseraufnahme- und Trocknungsprozesse verwendet. Aus dem Produktionsprozeß verbliebene Lösungsmittelreste — hauptsächlich Ethanol — wurden mit einer Instrumentenanordnung Quadrupolmassenspektrometer-Derivatograph bestimmt. Mittels dieser Ergebnisse konnten einige Schlußfolgerungen betreffs des Mechanismus der Wasser- und Lösungsmittelaufnahme getroffen werden.
(), . , , . . , , , -, . , .相似文献