Pore formation in polyimide irradiated by high-energy ions and the properties of the obtained membranes

The optimum conditions are determined for etching latent Kr tracks in sodium hypochlorite solution to prepare polyimide track membranes (PI-TMs) with cylindrical pores and the electrosurface properties of the membranes are investigated. The stability of the porous structure of PI-TMs is studied at elevated temperatures (up to 250°C) in aggressive media (pH 1–12). It is shown that the porous structure of PI-TMs is characterized by enhanced chemical and thermal stability.     

Kinetics of propylene epoxidation with hydrogen peroxide catalyzed by extruded titanium silicalite in methanol

The kinetics of propylene oxidation into propylene oxide in the presence of extruded titanium silicalite was studied. Based on the experimental data, a kinetic model of the process was designed and the activation energies of the target and side reactions, the rate constants, and the adsorption equilibrium constants were determined. The adequacy of the proposed kinetic model was verified on a continuously-operated test bench laboratory unit.     

Role of the paramagnetic nickel(I) complex in the catalytic dimerization of norbornadiene

In a joint investigation of the kinetic laws of the catalytic cyclodimerization of norbornadiene in the presence of bis-³-allyl complexes of nickel by gas chromatography and ESR, a definite correspondance in the change in the concentrations of norbornadiene, its dimers, and the paramagnetic nickel(I) complex was detected. The absence of an ESR signal in model systems, as well as the substantial differences in the relative amounts of Ni(I) when bis-₃ -allyl nickel complexes of different structure were used, suggests that paramagnetic Ni(I) does not participate as one of the intermediates in the catalytic process.M. V. Lomonosov Moscow Institute of Fine Chemical Technology. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 4, pp. 513–516, July–August, 1991. Original article submitted October 16, 1989.     

Transformations of β-Hydroxo-Substituted η<Superscript>3</Superscript>-Allyl Pd Complexes in Neutral and Weakly Acidic Solutions

The oxidation of some β-hydroxo-substituted η³-allyl Pd complexes based on the simplest 1,3-dienes is studied by the ¹H and ¹³C NMR methods in neutral and weakly acidic methods. The composition of the reaction products is determined by the nature of the oxidizing agent and the structure of allyl fragment. The method of selective oxidation of the β-carbon atom of the allyl ligand with the allyl-metal bond remaining unchanged is suggested.     

Unusual selective allylation of norbornadiene in the presence of palladium nanoclusters

The reaction of norbornadiene (NBD) with allyl acetate in the presence of the nanocluster Pd₁₄₇phen₃₂O₆₀(OCOBu^t)₃₀ (Pd-147; phen is 1,10-phenanthroline) and PPh₃ in acetonitrile is nonselective and is accompanied by the decomposition of the cluster, affording the same allylation products of NBD as the reaction with Pd₃(OAc)₆ or Pd(dba)₂ (dba is dibenzylideneacetone) combined with PPh₃. In contrast, in the ionic liquid [bmim][BF₄] (bmim is 1-butyl-3-methylimidazolinium), the Pd-147 is not decomposed and the reaction occurs selectively to give methylidene(vinyl)norbornene as the sole product. The data obtained suggest that in an ionic liquid, the reaction under study is catalyzed by the nanocluster Pd-147 rather than by the products of its decomposition.     

Regularities of the heterogeneous catalytic hydrogenation of 5-vinyl-2-norbornene

Russian Chemical Bulletin - The liquid-phase hydrogenation of 5-ethenylbicyclo[2.2.1]hept-2-ene (5-vinyl-2-norbornene, VNE) in the presence of the palladium catalyst Pd/γ-Al2O3 (PC-25) in an...     

The catalytic activity of bimetallic Pt—Pd polymer nanocomposites in formic acid oxidation

The platinum-palladium/Nafion metal—polymer nanocomposites were synthesized by chemical reduction of metal ions in water—organic reverse microemulsion solutions. The catalytic activity of the synthesized polymer composites with bimetallic Pt—Pd nanoparticles was estimated in the oxidation of hydrogen and formic acid.     

Interaction of norbornadiene with allyl acetate in the presence of Ni0 complexes: a DFT modeling

Russian Chemical Bulletin - Catalytic allylation of norbornadiene in the presence of Ni0 phosphite complexes resulting in 3-methylenetricyclo[4.2.1.02,5]non-7-ene was studied within the framework...     

Palladium carbonyl complexes with anions of N-heterocyclic carboxylic and pyridine-2-sulfonic acids

Synthesis, spectral characteristics, and structure of palladium(I) carbonyl complexes containing anions of N-heterocyclic carboxylic acids and pyridine-2-sulfonic acid of the general formula [Pd(CO)(NHC-CO₂)]n/[Pd(CO)(NHC-SO₃)]n, where NHC is an N-heterocycle, were described. The resulting complexes can be attributed to a binuclear structure with bridging or terminal coordination of carbonyl ligands depending on the nature of the substituents in the heterocycle.

     

The influence of the phosphine ligand nature on palladium catalysts in the norbornadiene allylation with allyl formate

Russian Chemical Bulletin - The effect of the electronic and steric characteristics of phosphine ligands on the catalytic properties of palladium catalysts in the allylation of norbornadiene with...