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1.
The composition of products from the interaction of ethylene with some o oxidants, catalyzed by palladium acetate in acetic acid has been studied, An assumption is made on the possible reason for the influence of such oxidants on the selectivity of formation of ethylene glycol ethers.
, , . .
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2.
Hydrogen-oxygen titration and carbon monoxide chemisorption of silica supported palladium have been investigated, using the pulse chromatographic technique. An excellent agreement between metal surface areas derived from both methods was observed.
H2–O2 . , .
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3.
Curves of the temperature-programmed desorption (TPD) of ammonia from zeolites were evaluated with several kinetic models. An approximately linear correlation was found between the activation energy of desorption or the heat of adsorption of H zeolites with various Si/Al ratios and the intermediate electronegativity of the zeolites, the latter representing a measure of the acid strength.This result corresponds to the change in the high-frequency infrared band of the OH groups and also to the change in the heat of adsorption, determined by microcalorimetry. Thus, the TPD of NH3 is a useful technique for quantitative characterization of the acidic properties of several H zeolites.
Zusammenfassung Kurven der temperaturprogrammierten Desorption (TPD) des Ammoniak von Zeolith wurden mit verschiedenen Kinetischen Modellen ausgewertet. Ein annähernd linearer Zusammenhang wurde gefunden zwischen der Aktivierungsenergie der Desorption bzw. der Adsorptionswärme von NH3 an H-Zeolithen mit unterschiedlichem Si/Al-Verhältnis und der intermediären Elektronegativität der Zeolithe, die ein mass für die Säurestärke darstellt. Dieses Ergebnis entspricht der Verschiebung der hochfrequenten IR-Bande der OH-Gruppen und der mikrokalorimetrisch bestimmten Änderungen der Adsorptionswärme. Damit erweist sich die TPD von NH3 als brauchbare Methode zur quantitativen Charakterisierung der sauren Eigenschaften von H-Zeolithen.

- . - Si/Al , . , , . , - -.


The authors wish to thank Prof. K.-H. Steinberg and Dr. M. Hunger for the zeolite samples, and R. Bauermeister for the non-linear regression programme.  相似文献   

4.
The kinetics of the dehydrobromination of 1-bromo-2-methylpropane on alumina modified with NaI and KI have been investigated. A mechanism for the isomerization reactions on alumina modified with alkali halides is proposed in order to explain the catalytic behavior of iodide ion as compared with that of chloride and bromide ions, reported in a previous paper.
1--2- , NaJ KJ. , , , , .
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5.
The activity of platinum/alumina catalysts in cyclopropane hydrogenation has been investigated. Catalysts heated in exhaust gases are considerably less active in cyclopropane hydrogenation as compared to samples calcined in air. A relatively stable modification of the metallic surface is formed, probably as a result of coke or poison deposition.
- . , , , , , . , , .
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6.
Résumé On a déterminé les paramètres cinétiques des réactions de décomposition de quelques combinaisons complexes des halogénures et pseudohalogénures de cobalt, nickel, manganèse, cuivre et cadmium, avec l'ammoniaque, la pyridine et des pyridines substituées. Pour les réactions d'ordre zéro, les valeurs des facteurs préexponentiels, calculées en considérant comme étape limitante la diffusion du composant volatil à travers la couche de la substance décomposée, concordent de façon satisfaisante avec celles déterminées expérimentalement.
Kinetic parameters were determined for the decomposition reactions of some com plexes of cobalt, nickel, manganese, copper and cadmium halides and pseudohalides with ammonia, pyridine and substituted pyridines. For the zero order reactions, the values of the pre-exponential factors calculated assuming as limiting step the diffusion of the volatile component through the layer of the decomposed substance, are in satisfactory agreement with the experimental values.

Zusammenfassung Es wurden die kinetischen Parameter der Zersetzungsreaktionen einiger Komplexe der Halogenide und Pseudohalogenide von Kobalt, Nickel, Mangan, Kupfer und Kadmium mit Ammoniak, Pyridin und substituiertem Pyridin bestimmt. Bei den Reaktionen von Null-Ordnung zeigten die preexponentiellen Koeffizienten, berechnet, indem für die limitierende Stufe die Diffusion des flüchtigen Bestandteils durch die Schicht der zersetzten Substanz betrachtet wurde, gute Übereinstimmung mit den experimentellen Werten.

, , , , , . . , . .
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7.
Platinum(II) catalyzes the reduction of alkyl iodides to alkanes according to a mechanism involving oxidative addition of RI to Pt(II), reduction of the product complex RPt(IV) to RPt(II) by iodide ions and protolysis of the latter particle.
(II) , RI PtII, - RPtIV RPtII .
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8.
Polymerization of isoprene over Al2O3 doped with potassium and sodium vapors has been investigated. The product is polyisoprene with a high content of 3,4-structures.
Al2O3, . 3,4.
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9.
Upon calcination of vanadium-molybdenum catalysts in air at 500°C two ESR signals are observed. They are attributed to a solid solution of MoO3 in V2O5 (a) and to the incorporation of VO2+ into the compound V2MoO8 (b).
500°C - - , MoO3 V2O5, - VO+2 V2 MoO5.
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10.
If heated to around 270° in argon, [Ni(HSal)2] (H2Sal=salicylic acid) gives off gaseous H2Sal and forms [NiSal], which reacts with monoprotic ligands HL (e.g. 8-hydroxyquinoline) to form mixed-ligand complexes [NiHSalL], or with diprotic ligands H2L' (e.g. quadratic acid) to form dinuclear complexes [HSalNiL'NiHSal].
Zusammenfassung Die Komplexverbindung [Ni(HSal)2] spaltet beim Erhitzen auf 270 °C in Argon Salicylsäure ab und liefert [NiSal], das mit Monoproton-Liganden HL (z. B. 8-Hydroxychinolin) zu Gemischtliganden-Komplexen [NiHSalL], mit Zweiprotonen-Liganden H2L' (z. B. Quadratsäure) dagegen Zweikernkomplexe [HSalNiL'NiHSal] bildet.

[Ni(HSal)2] 270°, [NiSal], HL (., 8-) [NiHSalL] H2L [HSalNiLNiHSal].


The preparative and thermoanalytical part of this work was performed by C. Gribi, D. Noukakis and M. Piccand, who also drew the Figures.

This research was supported by the Swiss National Science Fundation, grant No. 2.053-0.99.  相似文献   

11.
5-Substituted 4-thio-6-azauracils [I, 6-alkylthio-3,4-dihydro-5-thioxo-1,2,4-triazin-3(2H)-ones] have been converted with hexamethyldisilazane in 3-trimethylsilyloxy-5-trimethylsilylthio-derivatives(II). These were condensed with 1-O-acetyl-2,3,5-tri-O-benzoyl-d-ribofuranose in the presence of anhydrous stannic chloride to afford the corresponding 1-(2,3,5-tri-O-benzoyl--d-ribofuranosyl)-4-thioxo-5-substituted-6-azauracil (III).  相似文献   

12.
The reaction of -cyano--aminocrotonic ester with DMFA diethylacetal gives 1-ethoxycarbonyl-1-cyano-2-(N-dimethylaminomethylene)-amino-4-dimethylaminobutadiene, the reaction of which with ammonium acetate and amines leads to 4-methylenepyrimidine derivatives. Condensation of -cyano--aminocrotonic ester with dimethylacetamide dieethylacetal gave 2-(ethoxycarbonylcyano)methylene-4-dimethylamino-6-methylpyridine. It was found that in an alkaline medium, 1-benzyl-4-(ethoxycarbonylcyano) methylenepyrimidine recyclizes into 1-benzyl-3-cyano-4-amino-2-pyridone.For Communication 52, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1109–1114, August, 1988.  相似文献   

13.
A microcolumn on-line preconcentration and separation system was developed for the flame atomic absorption spectrometric (FAAS) determination of trace levels of gold and palladium. The analytes were selectively adsorbed onto the microcolumn packed with 2-mercaptothiazole immobilized silica gel (MBTSG) in an acidity range of 0.1 to 6.0M HCl at a sampling flow rate of 4.0mLmin–1. The analytes adsorbed could be desorbed by a thiourea solution with a flow rate of 2.0mLmin–1. Most of the common coexisting metal ions at a concentration of 25.0mgmL–1 and anions at a concentration of 50.0mgmL–1 did not interfere with the preconcentration and determination of Au and Pd. The limits of detection (LOD), defined as three times the standard deviation of the blank (3), of Au and Pd are 10ngmL–1 and 26ngmL–1, respectively, with a preconcentration time of 60s. The relative standard deviation (RSD) is about 2.0% for 0.20µgmL–1 Au and 0.30µgmL–1 Pd. With a sample loading time of 30min, 6.7ngmL–1 Au and 10ngmL–1 Pd can be preconcentrated quantitatively. A geological sample, an anode slime and a secondary nickel alloy were successfully determined with the proposed method, and the results obtained showed good agreement with the certified values.Received December 23, 2002; accepted May 14, 2003 Published online August 8, 2003  相似文献   

14.
The structure of 2,3pentamethylene3,4dihydroquinazolone4 nitrate was determined by means of Xray diffraction. Analysis was performed of the geometry of the heterocyclic ring in 2,3tri, tetra, and pentamethylene3,4dihydroquinazolones4, quinazolines, and their salts with inorganic acids and complexes with metal ions. It is found that in the N(1)—C(2)—N(3) fragment in the bases of quinazolines and quinazolones4, the conjugation is less pronounced than that in the protonated (salt) forms.  相似文献   

15.
3-Cyanomethyl-4,6-dimethylmercaptopyrazolo[3,4-d]pyrimidine was synthesized on the basis of 3-cyanomethyl-4-cyano-5-aminopyrazole. Ribosylation of this product gave 1-(2,3,5-tri-O-acetyl--D-ribofuranosyl)-3-cyanomethyl-4,6-dimethylmercaptopyrazolo[3,4-d]pyrimidine in 63% yield and small amounts of the 1- and 2- isomers. A number of derivatives of 6-methylmercaptopyrazolo[3,4-d]pyrimidin-3-ylacetic acid and their 1-ribosides were synthesized. The 4-methylmercapto group was replaced by amino, hydrazino, oxo, N-piperidino, and N-morpholino groups. The nitrile group was saponified in an alkaline medium to carbamoyl and carboxy groups. The corresponding 4-morpholino and 4-piperidino derivatives were obtained by the reaction of 3-cyano-4,6-dimethylmercaptopyrazolo[3,4-d]pyrimidine per-O-acetylated 1--D-ribofuranoside with secondary cyclic amines. The high resistance of the 6-methylmercapto group to the action of nucleophilic agents and the higher reactivity of the 4-methylmercapto group as compared with the nitrile group are discussed. Data on the cytotoxic activity of the synthesized compounds were obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 536–545, April, 1981.  相似文献   

16.
Conclusions The 3-0- and 4-0-trityl ethers of the acetates of methyl -L- arid methyl -L-arabinopyranosides were synthesized. The glycosylation of the ethers with the aid of 3,4-di-0-acetyl-1,2-0-(1-exo-cyano)ethylidene--L-arabinopyranose and the subsequent deacetylation of the synthesized products yielded the disaccharides: methyl 4-0-(-L-arabinopyranosyl)-,methyl 4-0-(-L-arabinopyranosyl)-, and methyl 3-0-(-L-arabinopyranosyl)--L-arabinopyranoside; and methyl 4-0-(-L-arabinopyranosyl)-, methyl 4-0-(-L-arabinopyranosyl)-, methyl 3-0-(-L-arabinopyranosyl)-, and methyl 3-0-(-L-arabinopyranosyl)--L-arabinopyranoside.The assignment of the signals in the PMR and13C NMR spectra of the synthesized arabinopyranosyl biosides was carried out, allowing the determination of the type and configuration of the glycosidic bond by means of which the arabinopyranose residues are linked in the oligo- and polysaccharide chains.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 200–209, January, 1986.  相似文献   

17.
    
Summary By the reaction of -hydroxymethylene- and -dimethylaminomethylene-2,3-polymethylene-3,4-dihydroquinazolin-4-ones with acid anhydrides and primary and secondary amines, the corresponding -acyloxymethylene- and -mono(di)-substituted aminomethylene-2,3-polymethylene-3,4-dihydroquinazolin-4-ones have been synthesized. The addition of hydrocyanic acid (from acetone cyanohydrin) to the double bond of the methylene group of the -hydroxymethylene- and -dimethylaminomethylene-2,3-trimethylene-3,4-dihydroquinazolin-4-ones has led to -[cyano-(hydroxy)methyl1]- and -[cyano(dimethylamino)methyl]-2,3-trimethylene-3,4-dihydroquinazolin-4-ones.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 603–609, September–October, 1978.  相似文献   

18.
The principle of an apparatus using an isothermal continuous flow stirred tank reactor to study homogeneous gas phase reactions at space times of the order of 1 sec is given. With this apparatus, the induction period of neopentane pyrolysis (as an example) has been clearly shown.
, , 1 . , , .
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19.
IR spectra of oxygen adsorbed on SnO2 with and without lattice defects have been studied. At low temperatures oxygen is adsorbed on defect SnO2 in two forms of O 2 . This supports the earlier results obtained by ESR. The low-temperature forms of adsorbed oxygen (unrevealed in ESR spectra) were detected on defectless SnO2. High-temperature forms of adsorbed oxygen appear in the IR-spectra as bands due to vibrations of the cation-oxygen bond.
- SnO2. , O 2 , . SnO2 .
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20.
The kinetics of oxidation of glycine with aqueous chlorine has been investigated. The reaction is first order with respect to both molecular chlorine and glycine and inverse first order with respect to H+. The effect of various factors on the initial rate has also been studied. The kinetic parameters have been calculated and a possible mechanism is proposed.
. , H+. , . .
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