Temperature effects in the oxidation of aliphatic ketones by solutions of thallic sulfate

The oxidation of aliphatic ketones by thallium(III) sulfate in aqueous medium has been studied from the point of view of the temperature effect and the enthalpy-entropy relationship. It has been found that the isokinetic relationship is fulfilled in this case.

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(III) - . , .

     

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 . , — .

     

Reactivity of alkyl and polychloroalkyl radicals toward 1-hexene

The kinetics of CCl₃ radical addition to 1-hexene in CCl₃Br and CCl₄ media has been studied. The rate constant of CCl₃ addition to the double bond is shown to be independent of the solvent. The ratios between the rate constants of transfer and allyl chain termination for the alkyl and polychloroalkyl radicals have been estimated by competition methods. Activation parameters for the calculated rate constants are given.

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CCl₃- 1- CCCl₃Br CCl₄. , . . .

     

Temperature programmed reduction and oxidation of Ir/Al2O3 catalysts

3 % Ir/Al₂O₃ catalysts have been studied by means of temperature programmed reduction and oxidation. With growing degree of metal oxidation (higher T_ox) reducibility of the catalysts at low temperatures decreases.

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3% Ir/Al₂O₃ . ( ) .

     

Structure, activity and selectivity of V2O5-TiO2 catalysts for o-xylene conversion

The formation of needle shaped crystallites of V₆O₁₃ at low V concentrations on V₂O₅-anatase coated catalysts explains the low selectivity for phthalic anhydride during o-xylene oxidation. The (010) plane of V-oxide, most active for selective oxidation of o-xylene, is not accessible and the contact of this plane with the anatase faces promotes the anatase-rutile transformation and the incorporation and blocking of V⁴⁺ ions.

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V₆O₁₃ V , V₂O₅-, -. (010) , -, , - V⁺⁴.

     

Kinetic studies of catalytic epoxidation of Si-containing olefins by tert-butylhydroperoxide

Kinetics and products of the epoxidation of several substituted sila-cyclo-3-pentenes by tert-butylhydroperoxide (ROOH) in the presence of Mo(CO)₆ at 70°C in chlorobenzene have been studied and an epoxidation mechanism is suggested. Effective rate constants have beeb shown to be practically independent of the structure of olefins examined.

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, -3- (I–VI-) . (ROOH) Mo(CO)₆ 70°C . , .

     

054 Determination of clarithromycin and its R-14-hydroxy-metabolite in human serum and urine by reversed-phase HPLC and electrochemical detection

Summary Clarithromycin and its main metabolite R-OH-clarithromycin are determined in human serum and urine. The method is based on liquid-liquid extraction, reversed-phase chromatography and dual-mode coulometric detection. The method is fairly selective. No interferences were observed in samples from human volunteers. Detection limits were 0.05 mg/l serum and 1.3 mg/l urine.     

Cyclization of aroylacetic acids 2-carboxyphenylamides into 2-[(Z)-2-aryl-2-hydroxy-1-ethenyl]-4H-3,1-benzoxazin-4-ones. Crystal and molecular structure of 2-[(Z)-2-hydroxy-2-phenyl-1-ethenyl]-4H-3,1-benzoxazin-4-one

2-Carboxyphenylamides of aroylacetic acids undergo cyclization when treated with dehydrating agents to give 2-[(Z)-2-aryl-2-hydroxy-1-ethenyl]-4H-3,1-benzoxazin-4-ones. Crystal and molecular structure of the latter phenyl derivative was studied by X-ray crystallography. Original Russian Text ? E.S. Vostrov, A.A. Novikov, A.N. Maslivets, Z.G. Aliev, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 2, pp. 232–235.     

Thin-layer chromatographic detection and estimation of steroid sapogenins in fenugreek

Summary A thin-layer Chromatographic method was developed for the detection and estimation of the steroid sapogenins of fenugreek seeds and plant at its various stages of growth. It depends on the initial separation of the constituent sapogenins (diosgenin, tigogenin and gitogenin) effectively on silica gel and alumina chromatoplates (n-hexane/ethylacetate as solvent) followed by direct photometric estimation of each product separately with reference to a calibration curve. Errors of ± 6% were found with synthetic mixtures.

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Dünnschicht-chromatographischer Nachweis und Bestimmung von Steroidsapogeninen in BockshornkleeSteroidsapogenine. XIV

Zusammenfassung Das Verfahren wurde zur Untersuchung der Samen und der Pflanze (Trigonella foenum graecum L.) in verschiedenen Wachstumsstufen angewendet. Die Sapogenine (Diosgenin, Tigogenin und Gitogenin) wurden auf Dünnschichten aus Silicagel oder Aluminiumoxid mit Hilfe von n-Hexan/Äthylacetat-Gemischen getrennt und anschließend photometrisch mit Phosphormolybdänsäure direkt auf der Platte bestimmt. In synthetischen Gemischen wurden Fehler von ± 6% gefunden.

     

Kinetic model ofCO oxidation on nonuniform surface analyzed regardingCOads spillover, 2. homotopic method. Effect ofm1 surface portion

The homotopic method has been used to analyze the kinetic model of three-stageCO oxidation on two nonuniform surface patches conjugated byCO ₂ spillover. Diagrams of steady states depending on the portion of surface patchm ₁ at various temperatures and pressure ratiosP(O ₂)/P(CO) have been constructed. The ratios of different type patches corresponding to the maximum overall reaction rate have been found.