Disproportionation of N-arylhydroxylamines in the presence of hydrogenation catalysts and sulfur compound additives

Conclusions The yield of N-arylhydroxylamines increases in the liquid-phase catalytic hydrogenation of aromatic nitro compounds due to a reduction in the rate of the secondary transformations of these products upon the introduction of thiophene, sulfolane, and other sulfur compound additives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 489–490, February, 1985.     

Conversion of furan compounds in the presence of polymeric gel-immobilized catalysts

Based on studies of catalytic oligomerization of furyl alcohol, 2-furfurylydeneacetone and tetrachlorofuran in the presence of gel-immobilized complexes (GIC) Al(OPh)₃, BF₃ and Ti(OBu)₄, an oligomerization mechanism is suggested and supported experimentally.

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(), 2- () () - (), Al(OPh)₃, BF₃ Ti(OBu)₄. .

     

Carbonylation of methyl acetate in the presence of polymeric rhodium-containing catalysts

New catalytic systems based on RhCl₃ and polymeric nitrogen- and oxygen-containing supports were proposed for the carbonylation of methyl acetate to acetic anhydride. The catalytic systems possess a high activity typical of homogeneous catalysts. The high activity is retained upon the repeated use of the catalyst separated from the reaction products. The nitrogen-containing polymers of the chitosan type serve as cocatalysts. In their presence, the induction period disappears, and the catalytically active species are stabilized, thus enabling the replacement of expensive LiI for cheaper salts of this metal.     

Hydroformylation of olefins in the presence of rhodium carbonyl catalysts immobilized on polymeric pyrrolidinopyridines

The hydroformylation of olefins in the presence of catalytic systems based on RhCl₃ and polymeric pyrrolidinopyridines was studied. lt was shown that the catalytic system has high activity in the hydroformylation of isobutylene under conditions when the activity of conventional homogeneous catalysts is low. The polymeric catalysts are also thermostable. The effect of solvents on the catalytic properties of the system was studied.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1673–1675, July, 1996.     

Disproportionation of olefins on modified aluminum-rhenium catalysts

Conclusions The promotion of an aluminum-rhenium catalyst, containing 0.2–0.5% of Re₂O₇, by molybdenum oxides and tetraalkylstannanes increases its activity substantially in the disproportionation of olefins.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1623–1625, July, 1979.     

Epoxidation of propylene with tert-butyl hydroperoxide in the presence of heterogeneous polymeric catalysts

A series of heterogeneous polymeric molybdenum containing catalysts on the basis of weak acid cation exchanger Amberlite IRC-84 in an organic and water medium was prepared. The catalysts activity and selectivity in the epoxidation of propylene with tert-butyl hydroperoxide are compared. Data about the chemical structure of catalytically active molybdenum containing centres of the modified cation exchanger were obtained.

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, , IRC-84 . .. , .

     

Heterogeneous phase transfer catalysts 1. Synthesis and catalytic properties of polymeric crown-ethers on inorganic supports

A number of new heterogeneous phase transfer catalysts based on polymeric dibenzo-crown-ethers supported on the carbonaceous material Sibunite, ultrafine diamonds, or silica gel are synthesized. The activity of several of the catalysts for the reaction of 1-bromooctane with KI is higher than that of previously known analogs. The catalytic effect depends on the support, linker, and solvent.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1257–1262. June. 1990.     

Ni-Cu catalysts on ceramic supports

The physicochemical and catalytic characteristics of catalysts fabricated on ceramic supports of various types was studied. The influence exerted by addition of cobalt and manganese on the catalytic activity of supported nickel-copper catalysts in high-temperature treatment of off-gases to remove nitrogen oxides was studied.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 9, 2004, pp. 1501–1509.Original Russian Text Copyright © 2004 by Dulnev, Efremov, Obysov, Golosman, Yakerson.     

Cumene hydroperoxide decomposition in the presence of metal complex catalysts supported on amorphous SiO2

By the method of molecular deposition, ions of CrO ₂ ²⁺ VO³⁺ and MoO ₂ ²⁺ were supported on a matrix of amorphous SiO₂. Different types of organic ligands were supported subsequently on the surface compounds so formed. The catalytic activity of the samples was studied in the decomposition of comene hydroperoxide.

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SiO₂ CrO ₂ ²⁺ , VO³⁺, MoO ₂ ²⁺ . . .

     

Nano-thin film formation on polymeric supports

Macromolecular electrolytes thin films of nanometer thickness on a surface of polymeric membrane have been prepared by a simple method using well controlled nano-sized materials such as star shaped macromolecules, brushes and dendrimers, and characterized by the gas transport properties. Metal ions in macromolecular electrolytes are readily reduced by UV irradiation to form metal nanoparticles as well as metal nanoparticle pattern adhered on a polymer support. To cite this article: J. Won et al., C. R. Chimie 6 (2003).     

Disproportionation of ethylbenzene in the presence of C8 aromatics

The selective synthesis of p-diethylbenzene (p-DEB) by disproportionation of ethylbenzene (EB) in the presence of aromatics like m-and p-xylene isomers has been studied over a pore size regulated HZSM-5 catalyst. The industrial feed having different compositions of ethylbenzene and xylene isomers was used for the experimentation. Hence, they were expected to hinder the movement of reactant molecules both on the external surface and within the zeolite channels. It was observed that irrespective of the different feed compositions the concentration of the xylene isomers was intact in the product. There is no other byproducts formation like para-ethylmethyl benzene. The effects of varying the concentration of aromatic compounds in the feed on ethylbenzene conversion and product distribution over the parent and modified H-ZSM-5 catalyst have been discussed. Ethylbenzene disproportionation reaction follows the pseudo first order reaction with an activation energy of 8.6 kcal/mol.     

Immobilization of synthetic glycopeptides on polymeric supports

The synthesis of the 6-aminohexyl -glycoside of O-(N-acetylglucosaminyl)-(14)-MDP (GMDP) is described. Conjugates with polyacrylamide, including lipophilic conjugates (containing phosphatidylethanolamine residues) and biotinylated polymeric probes with MDP specificity have been obtained on the basis of -spacered glycopeptides. Conjugates of MDP with dextran have also been synthesized.Simferopol' State University, 4 Yaltinskaya ul., Simferopol', Crimea, Ukraine. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 104–111, January–February, 1998.     

Homodimerization of bicyclo[2.2.1]-2-heptene in presence of complex nickel catalysts

Conclusions Norbornene is dimerized in the presence of a nickel-containing catalytic system to give exo-2-(4-methylenecyclohex-1-en-3-yl)norbornane in 67% yield.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 910–913, April, 1979.     

H2S-promoted thermal isomerization of cis-2-pentene to 1-pentene and trans-2-pentene around 800 K

H₂S accelerates the thermal isomerization of cis-2-pentene (P2c) to 1-pentene (P1) and trans-2-pentene (P2t) to around 800 K. This effect is interpreted on the basis of a free radical mechanism in which 2-pentenyl and thiyl radicals are the main chain carriers. P1 formation is essentially explained by the competing processes: P2t formation is due to addition-elimination processes: the importance of which has been evaluated against process (?4μ): The following ratios of rate constants have been measured and are discussed: (RT in cal mol^?1).