Influence of preparation conditions on activity and stability of catalysts for 3-thiolene-1, 1-dioxide hydrogenation

Dispersity of -Al₂O₃-supported palladium and activity and selectivity of these catalysts in hydrogenation of 3-thiolene-1,1-dioxide to thiolane-1,1-dioxide have been found to be dependent on the composition of impregnating solutions and the additional chemical treatment prior to reduction. This effect is due to the changes in Pd²⁺ mobility over the support surface.

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-Al₂O₃ , 3--1,1- -1,1- . Pd²⁺ .

     

Sulfur resistance of supported metals in 3-thiolene-1,1-dioxide hydrogenation

Supported platinum metals are deactivated in the liquid phase hydrogenation of 3-thiolene-1,1-dioxide. The sulfur resistance of Rh and Pd is by 1–2 orders of magnitude higher than that of Pt, Ir, Ru and Os. The metal resistance normalized to its surface area does not depend on its dispersity and the nature of the support.     

Palladium activity in 3-thiolene-1,1-dioxide hydrogenation in the presence of alkalis

Surface acidity/Basicity of mixed oxides of La and Zn activated at three different temperatures were determined. The data have been correlated with the catalytic activity for liquid phase reduction of cyclohexanone in isopropanol.     

AlPO4-supported rhodium catalysts, VII, liquid-phase hydrogenation of Ph?CH=CH?R compounds

The liquid-phase hydrogenation of Ph–CH=CH–R substrates (E isomer) has been studied using rhodium supported at 1 wt% on two AlPO₄ and an AlPO₄–SiO₂ catalyst. The reaction is zero order with respect to the substrate and first order with respect to hydrogen. The reaction rate has been found to be dependent on the support used, although the selectivity of the C–C double bond hydrogenation is 100%, except for E-3-phenyl-2-propen-1-ol and Ecinnamaldehyde which produce parallel isomerization-hydrogenolysis and undergo strong adsorption on the catalyst surface (autopoisoning), respectively. There is not a clear relationship between the electric or steric effects and the reaction rate.

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Ph–CH=CH–R (E ) (1 . %), AlPO₄ AlPO₄–SiO₂. . , C–C 100%, E-3--2--1- E- , - (), . .

     

The interaction of 3-methyl-4-nitro-3-thiolene-1,1-dioxide with aliphatic amines

The reactions of 3-methyl-4-nitro-3-thiolene-1,1-dioxide with highly basic amines (pK _a of HB⁺ = 8.97–13.27), morpholine, piperazine, piperidine, cyclohexylamine, diphenylguanidine, and guanidine, proceed via deprotonation of methylene group at the C² atom of sulfolene ring with formation of ammonium thiolene nitronates. The products were characterized by IR, UV, and NMR (¹H, ¹³C, ²D) spectroscopy methods.     

Polymer-supported palladium and rhodium species as hydrogenation catalysts

The synthesis of new copolymers containing amino and heterocyclic ligands and their use for anchoring Pd and Rh species is described. The supported catalysts are effective for the hydrogenation of alkenes, dienes, alkynes, and nitrobenzene under very mild conditions. The catalysts have been characterized by chemical analysis, particle size measurement, IR, and x-ray photoelectron spectroscopy. Relative reactivities and the effects of substrate structure, solvents, catalyst loading, anchoring ligands, metal species, and particle size on the rates of hydrogenation have been determined using a wide variety of substrates. The kinetics of hydrogenation have been analyzed using concepts suitable under slurry reaction conditions. Comparisons between different oxidation states of the same metal and between different metal species have also been made. The recycling efficiencies of the catalysts have been determined and found to be very good. © 1997 John Wiley & Sons, Inc.     

Fractal analysis of co hydrogenation over rhodium catalysts

A fractal scaling law has been applied to products of carbon monoxide hydrogenation over silica supported rhodium catalysts. The results indicate structure sensitivity and that the type of structural sensitivity is product dependent.

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Deactivation of silica supported Pd catalysts during liquid-phase hydrogenation

Summary Large pore MCM-41 was found to provide a better stabilization of Pd particles than amorphous SiO₂ during liquid phase hydrogenation. Pd/large pore MCM-41 exhibited higher hydrogenation activities as well as lower amount of metal loss by Pd leaching.     

Preparation of rhodium–phyllosilicate catalysts without leaching in liquid-phase 1-hexene hydrogenation

Rhodium catalysts have been prepared on palygorskite and montmorillonite (clay) supports by reduction with hydrogen (1 atmosphere) at room temperature of a cationic organometallic rhodium compound anchored to the support. The activity of these catalysts for the hydrogenation of liquid-phase 1-hexene remains constant with increase of prehydrogenation time and with re-use for several runs. No rhodium leaching is observed.     

Crystal and Molecular Structure of 4-Nitro-2-oximino-3-phenylamino-3-thiolene-1,1-dioxide

The present publication reports the results of X-ray diffraction (XRD) analysis of 4-nitro-2-oximino-3-phenylamino-3-thiolene-1,1-dioxide crystals (I). The synthesis and the useful properties of this class of compounds are reviewed in [1]. It is noteworthy that previously [2] an X-ray structure analysis has been performed for another compound from this class, 3-methyl-4-nitro-2-oximino-3-thiolene-1,1-dioxide (II), which was assumed to exist in nitrone form. The XRD data for compound I disprove this assumption.     

2-Benzylidene-3-methyl-4-nitro-3-thiolene-1,1-dioxide and Its Analogs in Aza-Michael Reaction

2-Benzylidene-3-methyl-4-nitro-3-thiolene-1,1-dioxide and its analogs have been introduced in the aza-Michael reaction with hydrazine derivatives. Novel polysubstituted nitrosulfolenes have been obtained; their structures have been confirmed using ¹Н NMR and IR spectroscopy as well as X-ray diffraction analysis.     

Osmium liquid-phase catalysts for hydrogenolysis of saturated hydrocarbons and hydrogenation of arenes

Reduction of OsO₄ by molecular hydrogen in alkane (cycloalkane) or benzene (toluene) solution produces small-ligand clusters of osmium of composition Os_1.5–2.5. CH_0–2 with a particle size 10–40 Å and a specific surface area of 34–46 m²/g. Hydrogenation of dry catalyst produces methane. The small-ligand osmium clusters obtained effectively catalyze hydrogenolysis of alkanes and cycloalkanes at 100–150°C and =5 MPa and hydrogenation of benzene at 20°C and =0.1 MPa.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2428–2433, November, 1989.     

Palladium catalysts supported on oligomeric aramides in the liquid-phase hydrogenation of phenylacetylene

The catalytic behaviour of palladium supported on oligomeric aramides has been investigated in the liquid phase selective hydrogenation of phenylacetylene to styrene, by comparison with conventional Pd-supported systems, such as Pd/carbon. Pd/Al₂O₃ and Pd/SiO₂. The influences of the reduction temperature and metal loading on the activity/selectivity behaviour of the title reaction are explained in terms of different reducibility patterns of the catalysts, as well as in the light of a peculiar support effect of the organic matrix on Pd particles.