M. A. Ryashentseva

Electronic State of Dispersed Metals on Supports and Their Catalytic Activity in Some Reactions of Hydrocarbon Conversion

Valence states, surface concentrations and electronic structure of Hi, Pd, Re, Rh, Ru and Pt supported on γ-Al 2 O 3 -j, SiO 2 and Y zeolite have been studied by XPS at different stages of catalysts preparation, activation and some catalytic reactions. In active forms of the catalysts of benzene hydrogenation (Re/γ-Al 2 O 3 ) and ethylene cyclotrimerization (Rh/γ-Al 2 O 3 F) metals are present as electron-deficient clusters.

The equilibrium yields of thiophene in the interaction of C4-hydrocarbons with sulfur dioxide or hydrogen sulfide

1. Thermodynamic calculations were made of the reactions of synthesis of thiophene from n-butane, butylenes, and 1,3-butadiene and sulfur dioxide or hydrogen sulfide, and the equilibrium yields of thiophene were determined at 700–900°K and atmospheric pressure. 2. The experimental yields of thiophene in the presence of the most activity catalysts comprised 20–33% in the case of SO2 and 32–44% (or 60–90%, considering side reactions) in the case of H2S with respect to the equilibrium yields.

Synthesis of tetraorgano-substituted silanes with the benzo[b]thiophene moiety

Catalytic dehydrocyclization of dimethyl(o-tolyl)- and dimethyl-4-(m-xylyl)-(benzo[b]thien-2-yl) silanes has given 11,11-dimethyl and 8,11,11-trimethyl-6,11-dihydro-11-silabenzo[b]naphtho[2,3-d]thiophenes, which were oxidized to the ketones. Previously unknown diorganobis(benzo[b]thien-2-yl)silanes have been obtained.

Effect of the nature of the carrier and reduction conditions on the properties of rhenium catalysts of hydrogenation of ethyl acetate

Conclusions1.It was shown that the activity of 0.5% Re/α-, δ-, θ-, and γ-Al2O3 catalysts in the reaction of hydrogenation of ethyl acetate into ethanol is a function of the nature of the carrier and reduction conditions to a smaller degree than in the side reactions of formation of diethyl ether and hydrocarbons. Re/θ-Al2O3 exhibits the maximum activity and Re/α-Al2O3 exhibits the maximum selectivity.2.It was found that diethyl ether is only formed on Re/γ- and θ-Al2O3 catalysts. Preliminary treatment of these samples with H2 at 500°C insignificantly decreases the yield of ethanol, increases the yield of diethyl ether, and almost totally suppresses the side reaction of hydrogenolysis of the alcohol into hydrocarbons.3.Kinetic data were obtained which confirm the possibility of formation of diethyl ether directly from ethyl acetate, by-passing the stage of formation and desorption of ethanol.

Catalytic methods for obtaining thiophene and alkylthiophenes from petroleum refining products and sulfur-containing organic compounds

This review is devoted to catalytic methods for obtaining thiophene and alkylthiophenes from C2-C6 hydrocarbons and from various organosulfur compounds — aliphatic sulfides, mercaptans, alkylthiophenes, thiophane, and sulfones. Multicomponent chromium-containing catalysts have considerable activity in the majority of the reactions. The catalytic method for obtaining thiophene and alkylthiophenes by the reaction of C2-C6 hydrocarbons with hydrogen sulfide may be the most promising one.

Catalytic reduction of 2-thiophenaldehyde and 2-acetothienone

A catalyst, rhenium heptasulfide, has been found for reducing 2-thiophenaldehyde and 2-acetylthiophene to the corresponding alkylthiophenes. The reduction conditions found were: temperature 170° -190° C, hydrogen pressure 130 atm, time 3–6 hr. Reduction of 2-thiophenaldehyde in methanol in the presence of rhenium heptasulfide gives 2-methoxythiphene, while corresponding hydrogenation of 2-acetylthiophene in ammonia plus dioxane gives 2-(α -aminoethyl) thiophene.

Some reactions of 8,11,11-trimethyl-11-silabenzo[b]naphtho-[2,3-d]thiophen-6-one at the carbonyl group

Reactions of C- and N-nucleophiles at the carbonyl group of 8,11,11-trimethyl-11-silabenzo-[b]naphtho[2,3-d]thiophen-6-one have been studied. PMR Spectroscopy showed that condensation with aniline gives a mixture of the Z- and E- isomers of the corresponding azomethine. Reaction with n-butyl and phenyllithium gave tertiary alcohols, the molecular structure of which was proved using X-ray crystallography.

Reactions of 1-vinyl-4,5,6,7-tetrahydroindole and its mixtures with 4,5,6,7-tetrahydroindole in the presence of Cr- and Pd-coated catalysts

In the presence of Cr- and Pd-coated γ-alumina catalysts, 1-vinyl-4,5,6,7-tetrahydroindole (VTHI) and its mixtures with 4,5,6,7-tetrahydroindole (THI) are converted into 1-ethyl-4,5,6,7-tetrahydroindole (1-ETHI), indole, and 2-ethylindole, in proportions dependent on the reaction conditions and the catalyst. Over a sulfided 1% Pd-γ-alumina catalyst in the presence of hydrogen at 200°C, VTHI is converted into 1-ETHI and THI. When the temperature is raised to 300–350°C, indole is formed in addition to these products. A 1∶1 mixture of VTHI and THI over 1% Pd-γ-alumina at 300°C gives indole and 2-ethylindole, over a sulfided 1% Pd -γ-alumina catalyst at 200°C, 1-ETHI, and over a Cr oxide catalyst at 500°C, indole.

Heterocyclizing properties of ferrisilicate in the reaction of n-pentane with hydrogen sulfide

Unlike the iron-modified pentasil, the ferrisilicate has high heterocyclizing activity in the formation of 2-methylthiophene from hydrogen sulfide and n-pentane. During the reaction and the subsequent regenerations a considerable proportion of iron ions leaves the ferrisilicate lattice. The heterocyclizing activity is probably related to the formation of a highly dispersed Fe sulfide phase in the zeolite channels.

Hydrogenation of cyclohexene and benzene on Re2(CO)10

AbstractCyclohexene and benzene are completely hydrogenated to cyclohexane in the presence of Re2(CO)10 at 230°C,