Regioselectivity of styrene carbonylation in the presence of palladium(II) complexes

The influence of a catalyst on regioselectivity of styrene carbonylation in ionic liquids catalyzed by palladium(II) complexes was studied. The mechanism of the migration insertion of styrene at the palladium-hydrogen bond determining the regioselectrivity of the whole reaction, which is treated as electrophilic addition to the multiple bond of styrene, was studied. A study of the structure of intermediate complexes formed at this stage was performed using the B3LYP method of density functional theory.     

Simulation of the mechanism of styrene carbonylation in the presence of palladium(II) complexes

The mechanism of styrene carbonylation in the presence of a palladium(II) complex has been investigated by quantum chemical methods. The migratory insertion of styrene into the palladium-hydrogen bond of hydride π-complexes is considered in detail. This process determines the regioselectivity of the reaction.     

Effect of heteropolyacids on the hydrocarboxylation of styrene: comparative study on hydrocarboxylation and hydroesterification reactions

The hydrocarboxylation and the hydroesterification of styrene was studied in the presence of PdCl₂(PPh₃)₂ as a catalyst. The effect of the addition of the heteropolyacids of a general formula H_3+nPMo_12-nV_nO₄₀ (HPA-n, n=1-4) on the hydrocarboxylation and the hydroesterification of styrene was considered.     

Mono- and dinuclear bioxazoline-palladium complexes for the stereocontrolled synthesis of CO/styrene polyketones

The coordination chemistry of the chiral bioxazoline ligand (4S,4'S)-2,2'-bis(4-isopropyl-4,5-dihydrooxazole) to Pd(II) provides evidence that the ligand bonding can occur either through chelation of one Pd(II) ion leading to a mononuclear species with the expected cis geometry, or by double bridging of two Pd(II) ions giving a dinuclear complex with trans geometry. The species in solution are identified by 1H NMR spectroscopy. Both the mononuclear and the dinuclear complexes promote the CO/styrene copolymerization, yielding the corresponding polyketone with a fully or a predominantly isotactic microstructure, depending on the reaction medium. The nature of the anion present in the palladium precatalysts affects the polyketone stereochemistry. MALDI-TOF analysis of the copolymers synthesized reveals the presence of p-hydroxyphenolic end-groups, thus confirming and explaining the role of 1,4-hydroquinone as a molecular weight regulator.     

Hydrogenation of vinylpyridines and styrene in the presence of the palladium chlorodimethylsulfoxide complex

The rate of hydrogenation of the vinyl group ofα-,Β, andγ-vinylpyridines decreases as its distance from the nitrogen atom increases in the presence of the palladium chlorodimethylsulfoxide complex. In binary mixtures of these vinylpyridines, theγ isomer is reduced before the other two isomers.     

Alk-2-yn-1-amines in the synthesis of substituted quinolines in the presence of palladium complexes

An effective one-step procedure has been developed for the synthesis of 4- and 2,3,4-substituted quinolines via reaction of o-iodoaniline with alk-2-yn-1-amines in the presence of Pd(OAc)₂ as catalyst.     

Mild alkoxycarbonylation of olefins in the presence of palladium complexes

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, p. 743, March, 1989.     

Interaction of CO2 gas with silicone elastomer at high ambient pressures

Interaction of high-pressure CO₂ gas with a silicone elastomer, and to a lesser extent, with a nitrile rubber and a PTFE have been investigated. Sorptive dilations of the polymers were measured with the help of custom-made piezoelectric ultrasonic transducers under gas pressures of up to ca. 22 MPa at 42°C. The gas mass sorption was determined by a vibrating reed probe. For the silicone elastomer system the dilation isotherm mimics the sorption isotherm. The partial molar volume (PMV) of the absorbed CO₂ gas in the silicone elastomer has been computed. A significant drop in the PMV value is observed when the CO₂ gas becomes supercritical. In the transition region, the transmission of ultrasonic signals through the specimen indicated the formation of discrete small (estimated as about 60 μm in diameter) high density zones of CO₂ in the rubber matrix. The plasticization effects of the absorbed high pressure CO₂ gas have been identified from the interpretation of the changes in the acoustic longitudinal modulus obtained from ultrasonic transmission measurements. The effects of rapid gas decompression on the structural integrity of the various polymers have also been determined. Significant inflation of certain specimens occur toward the latter stages of the decompression cycle. The initiation and development of internal cracks or bubbles was followed by monitoring the ultrasonic signal attenuation.     

Terpolymerization of carbon monoxide, ethylene and styrene in the presence of supported palladium catalyst

Terpolymers of carbon monoxide with ethylene and styrene are synthesized in the presence of supported palladium catalyst in toluene and heptane medium for the first time. The terpolymerization rate exceeds the rate of carbon monoxide and ethylene copolymerization. The maximum terpolymer yield amounts 7.9 g per g of supported catalyst per hour or 321 g per g of palladium per hour. The influence of reaction temperature, pressure, 1.4-benzoquinone amount and co-monomers mole ratio on the yield and the composition of terpolymer have been studied. The NMR ¹³C data obtained testify to a distribution of ethylene and styrene units in terpolymer with the predominance of short blocks at equal contents of comonomer units.     

Optical emission spectroscopy diagnostics of inductively-driven plasmas in argon gas at low pressures

An optical emission spectroscopy method for determination of electron temperature, electron density and gas temperature is developed and applied for diagnostics of inductively-driven argon discharges in a cylindrical geometry. The discharges are maintained at frequency 27 MHz, applied power varied in the limits P = (90 – 160) W and gas pressure in the range p = (1.1 – 117.3) Pa. The method combines measurements of emission spectral line intensities and profile broadenings with a collisional-radiative model of argon plasma at low pressure. The model is employed for investigation of the plasma kinetics governing the population densities of 3p⁵4s and 3p⁵4p argon configuration levels, treated separately. In the numerical calculations the electron density and electron temperature are varied whereas the values of the third plasma parameter — the gas temperature — are involved as obtained data from the experiments. Comparison of the experimental results of the line-intensity ratios with those calculated by the model yields the values of the electron density and temperature. The dependence of the electron temperature, electron density and gas temperature on the discharge conditions is obtained and discussed in the study.     

Copolymerization kinetics of ethylene and carbon monoxide in the presence of palladium complexes

The copolymerization kinetics of ethylene and carbon monoxide has been studied for the catalysts: Pd(C₅H₇O₂)₂-P(C₆H₅)₃-p-CH₃C₆H₄SO₃H in the medium of acetic acid (system A), and Pd(CH₃COO)₂-CF₃COOH - (C₆H₅)₂P(CH₂)_nP(C₆H₅)₂(system B), where n=1−6, in the medium of methyl alcohol. The cationic palladium(II) -diphosphine complexes: (Dppp)₂Pd(CF₃COO)₂ (I) and [(Dppp) Pd(μ-OH)₂Pd(Dppp)] (CF₃COO)₂ (II) have been synthesized and investigated by IR, electrospray mass spectrometry and elemental analysis methods. A comparative study of the copolymerization kinetics in the presence of these complexes and system B has been carried out.     

Mechanism of CO oxidation by oxygen in the presence of palladium(ii) bromide complexes: a quantum chemical modeling

Russian Chemical Bulletin - Mechanisms of CO oxidation by oxygen in the PdBr2-LiBr-MeCN-H2O system in the absence and in the presence of iron(ii) phthalocyaninate (PcFe) as co-catalyst were studied...     

Copolymerization of carbon monoxide with ethylene in the presence of palladium phosphine complexes

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2181–2182, September, 1990.     

Alternating copolymerizations of styrene derivatives and carbon monoxide in the presence of a palladium (II) catalyst

A series of styrene derivatives were synthesized from aromatic substances by Friedel-Crafts acylation, reduction, and dehydration. Alternating copolymers of styrene derivatives and carbon monoxide were prepared in the presence of a palladium(II) catalyst. The characterization of the polyketones produced was performed by use of ¹H-NMR, IR, WXRD, and EA methods. The thermal degradation of the regular alternating copolymer of carbon monoxide and styrene (STCO) has been studied by thermal gravimetry (TG). The TG spectra of solid samples were recorded both in nitrogen and in air. The degradation reaction order and activation energy were determined. The photodegradation of STCO was investigated. In addition, the block copolymerization of STCO with methyl methacrylate under UV irradiations was also studied. It is found that the tertiary amine can promote this photopolymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1283–1291, 1997