Presence Of Catalytic System Research Articles

One-pot process involving dehydration of cyclohexanol and alkoxycarbonylation of cyclohexene in the presence of catalytic system PdCl2-PPh3-p-toluenesulfonic acid

One-pot process involving dehydration of cyclohexanol and alkoxycarbonylation of cyclohexene in the presence of catalytic system PdCl2-PPh3-p-toluenesulfonic acid

Copolymerization of Butadiene with Ethylene in the Presence of Ni-containing Organometallic Catalytic Systems and Different Modifiers

Copolymerization of ethylene with butadiene was carried out in the presence of nickel diethyldithiocarbamate and various modifiers. Triphenylphosphines were selected as modifiers. Solutions of nickel diethyldithiocarbamates and said modifiers in aromatic solvents of various concentrations have been prepared. Their physicochemical parameters, particle sizes in solutions, as well as mutual solubility were determined. It was demonstrated that these complexes are readily soluble in aromatic solvents, and the particle size in solution is in the nanometer range. These complexes were tested in the processes of copolymerization of ethylene with butadiene in combination with various cocatalysts - (tri-, diethylaluminum chloride). The products synthesized in their presence were analyzed by various physicochemical methods and their structure was confirmed. It has been shown that oligomeric and copolymer products with the required structure can be in fact synthesized in the presence of these catalytic systems. The activity and selectivity of catalytic systems have been comparatively tested in liquid phase (co) polymerization processes. The composition and conditions have been found to have a significant effect on the activity and structure of the resulting products.

Monthmorillonite as an Effective Catalyst of the Polyphenences of Polyphenylene Sulphide

The synthesis of polyphenylene sulfide in the presence of catalytic systems based on montmorillonite and various lithium salts has been studied, and conditions have been identified that accelerate the process and obtain a polymer with a given microstructure. The rheological, thermal, and physicomechanical.

The Development of Effective Multifunctional Inhibiting Additives for Polymeric Materials

The synthesis of polyphenylene sulfide in the presence of catalytic systems based on various lithium salts has been studied, and conditions have been identified that accelerate the process and obtain a polymer with a given microstructure. The rheological, thermal, and physicomechanical properties of the obtained polymers were studied and the optimum temperature () and pressure (9-10 atm) were established upon the production of polyphenylene sulfide by high-temperature polycondensation of sodium sulfide and 1,4-dichlorobenzene in a solution of N-methylpyrrolidone, which increase the effectiveness of its synthesis.

Oligomerization of ethylene to linear α-olefins in the presence of complex catalytic systems based on zirconium carboxylates

The study considers the process of ethylene oligomerization in a medium of aliphatic and aromatic solvents in the presence of complex catalytic systems based on zirconium carboxylates, which were obtained from the fractions of naphthenic acids recovered from Baku oils and individual carboxylic acids. It was found that the catalytic activity and the molecular weight distribution (MWD) of the produced oligomeric products depend mostly on the solvent nature and the composition of zirconium complex. The ethylene oligomerization rate in the presence of catalytic systems based on zirconium carboxylates is 2–3 times lower in a medium of aliphatic solvents as compared to aromatic solvents; the obtained product has a narrow MWD and consists predominantly of С4-С10 fractions. Oligomeric products obtained in a medium of aromatic solvents have a broad MWD and in the presence of zirconium carboxylates comprise mostly С4-С18, while in the presence of zirconium naphthenates, С12-С18 and С20 fractions.

Carbozincation of Substituted 2-Alkynylamines, 1-Alkynylphosphines, 1-Alkynylphosphine Sulfides with Et2Zn in the Presence of Catalytic System of Ti(O-iPr)4 and EtMgBr

The EtMgBr and Ti(O-iPr)4-catalyzed ethylzincation of 1-alkynylphosphine sulfides with Et2Zn in diethyl ether followed by hydrolysis and deuterolysis affords corresponding β,β-disubstituted 1-alkenylphosphine sulfides with high yield. The EtMgBr and Ti(O-iPr)4-catalyzed reaction of 2-alkynylamines, 1-alkynylphosphines, and 1-alkenylphosphine sulfides with Et2Zn in various solvents was studied. It has been found that the reaction of 2-alkynylamines and 1-alkynylphosphines in methylene chloride, hexane, toluene, benzene, and anisole leads to the selective formation of 2-alkenylamines and 1-alkenylphosphine oxides after oxidation with H2O2.

BIOFUEL VIA INTERESTERIFICATION OF RAPESEED OIL WITH METHYL ACETATE IN PRESENCE OF POTASSIUM t-BUTOXIDE/THF

Transesterification does not allow to make full conversion of oil to biodiesel because the by-product glycerol cannot be included in the composition of biofuel. Interesterification constitutes a full conversion process with production of triacetin (TA) instead of glycerol, which can be included in the composition of biofuel and allows to increase its yield. Both interesterification and transesterification effectively occur only in presence of catalysts. Results of the investigation of heterogeneous and homogeneous catalysts indicate the superior importance of catalyst solubility in starting reaction mixture. Partial solubility can remarkably lower the activity of homogeneous catalyst and extremely increase that of formally heterogeneous one. The reaction mixture of interesterification reaction is less polar than that of transesterification, and potassium tert-butoxide (t-BuOK) should be more appropriate catalyst for interesterification than sodium methoxide which is used in most cases. The catalytic system t-BuOK/t-BuOH substantially increases the yield of TA and changes the properties of obtained biofuel. Whereas the content of the TA in the interesterification reaction mixture does not achieve the same level from the theoretically predicted as the FAME, the occurrence of side reaction between t-BuOH and TA cannot be excluded. This paper presents a study of the interesterification of rapeseed oil in presence of catalytic system t-BuOK/THF (catalytic system without alcohols) with the aim of establishing the influence of aprotic tetrahydrofuran to the proceeding the reaction, composition of reaction mixtures and their fuel properties. Obtained results show that the absence of alcoholic hydroxyl groups in the catalytic system insufficiently increases the activity of catalytic system but fails to increase the yield of FAME.

Mesoporous Nanostructured Materials for the Positive Electrode of a Lithium–Oxygen Battery

Nanostructured carbon materials (CMs), the structure can vary widely, are promising materials for the positive electrode of a lithium–oxygen battery (LOB). The electrochemical characteristics of CMs studied in model conditions and their porous structure, as well as testing them as an active material for the positive electrode in an LOB sample, show that nanotubes (CNTs) and Super P carbon black possess the highest charge–discharge characteristics in an aprotic solvent (DMSO). Mono- and bimetallic systems containing Pt, Pd, and Ru and synthesized on CNT and Super P allow one to reduce discharge and charge overvoltage. In the presence of catalytic systems, an improvement in the energy-conversion efficiency of up to 73–76.7% is achieved for the LOB positive electrode. The possibility of achieving a stable cycling process in an LOB with a positive electrode on the basis of developed catalysts and with a LiClO4/DMSO electrolyte is shown. For the first time, the positive influence of iodine (reducing the charge voltage to about 0.8–1.0 V as compared to the characteristics of an LOB using an electrolyte without additives) on the electrode characteristics of a Li–O2 cell with the highly electron-donating solvent DMSO is demonstrated.

Oxidation of Natural Gas to Dimethyl Ether at Presence of Catalytic System

Oxidation of Natural Gas to Dimethyl Ether at Presence of Catalytic System

Isoprene Polymerisation in the Presence of Catalytic Systems based on Gadolinium Compounds

Isoprene Polymerisation in the Presence of Catalytic Systems based on Gadolinium Compounds

Coupled hydrogenation of alkenes and arenes in the presence of catalytic systems based on cobalt Bis(acetylacetonate) and tributylphosphine

The effect of the composition of the catalytic systems based on Co(acac)2 and tertiary phosphines on the activity and efficiency of cobalt catalysts in the coupled hydrogenation of alkenes and arenes is reported. The process occurs in the presence of cobalt catalysts formed under the action of both organoaluminum compounds and tert-butoxy derivatives of complex aluminum hydrides. NMR and IR spectroscopic methods show that the interaction of the components of the catalytic systems yields mono- and/or trihydrido cobalt phosphine complexes, whose composition depends on the nature of the reducing agent and gas atmosphere. The homogeneous character of the process is hypothesized. The most probable schemes are proposed for the reaction mechanism, according to which the kinetic coupling of alkene (alkadiene) and arene hydrogenations is due to the fact that the reaction proceeds through a σ-alkyl or σ-alkenyl cobalt complex with two phosphorus-containing ligands.

Bimetallic Aluminum Complexes Modified with Chloride Ions of Mn (II), Fe (III), and Ni (II) for Pyrocondensate Oligomerization

The oligomerization processof pyrocondensatefraction wasperformed in the presence of catalytic systems which were synthesized by the reaction ofaluminium metal (Al) and dichloroethane (DCE) as the basic cataly st and after that were modified with metal

Hydroalkoxycarbonylation of isobutylene with polyhydric alcohols in the presence of catalytic systems based on palladium compounds and tertiary phosphines

The reaction of isobutylene hydroalkoxycarbonylation at low carbon monoxide pressures (≤2.0 MPa) with ethylene glycol and glycerol in the presence of catalytic systems based on Pd and mono- and bidentate organic phosphines has been studied. The effect of different conditions of the reaction in the presence of the Pd(Acac)2-PPh3-TsOH catalyst system on the ratio of the products, mono- and diglycolides (mono-, di-and triglycerides) of isovaleric acid has been investigated. The relative catalytic activity of a number of binary and ternary systems based on synthesized Pd(Acac)2, Pd(PPh3)4, and PdCl2(PPH3)2 complexes has been determined.

Catalytic activity of new nickel(II) formazanates in ethylene oligomerization

Thirteen mono- and three bisformazans containing one system of azahydrazone bonds have been synthesized, as well as mono- and binuclear complexes on their basis. The kinetic features of ethylene oligomerization in the presence of catalytic systems on the basis of AlEtCl2-activated Ni(II) formazanates differing in composition and structure have been studied. The structures of the mono- and binuclear complexes differ by substituents in the formazan ligand, which have an effect on the activity of the systems and the product composition. The catalytic activity of the binuclear complexes is several times below that of mononuclear Ni(II) formazanates.

Effect of the hydrodynamic action on the microstructure of butadiene-isoprene copolymers

270 In copolymerization of denies in the presence of Ziegler-Natta ioncoordination catalytic systems, each of the monomers affects the microstructure of units of the other monomer in the copolymer chain (1). For example, in copolymerization of butadiene with isoprene in the presence of catalytic systems based on titanium halides, an increase in the fraction of isoprene in the initial monomer mixture caused a

New hydrofluoropolyethers II: Physico-chemical characterization

We obtained, through an original multi step synthetic approach with 60–80% selectivity, a novel family of hydrofluoropolyethers (HFPEs) characterized by a macromeric perfluoropolyether (PFPE) body end-capped, on one or both sides, by a 1,1-difluoroethoxy group. We synthesized these HFPEs trough an apparently conventional hydrogenation of PFPE precursors end-capped by reducible acyl halide groups and subsequent Cl cleavage by hydrogen, promoted by UV light in presence of hydrogen radical donor or by a metal catalytic system in presence of H 2. The physico-chemical properties of these HFPEs were described and compared to those of similar perfluorinated or partially hydrogenated molecules, obtaining master curves of general validity when temperature dependent properties, like viscosity, were compared under temperature reduced condition. The contribution of the end-groups to the specific property, vanishing at a sufficient high molecular weight, was demonstrated more and more important at the lowest oligomerization degrees.

Ethylene oligomerization in the presence of catalytic systems based on nickel(II) formazanates

The influence of the temperature, the pressure, the Al/Ni molar ratio, and the position of chlorine-containing substituents in formazan ligands on the reaction kinetics and the product composition in the ethylene oligomerization catalyzed by thea system based on nickel(II) formazanates and ethylaluminium dichloride has been studied. It has been shown that effective metal complex catalyst systems can be prepared via varying the nature and the position of the substituents in the ligands.

Oligomerization of hexene-1 in the presence of catalytic systems on the basis of ionic liquids

The results of hexene-1 oligomerization in the presence of recyclable catalysts on the basis of chloroaluminate ionic liquids and in combination with Ti-containing complexes with “grafted ionic liquid” ligands are reported. The possibility has been shown of the selective preparation of products with an oligoalkylnaphthene structure with a narrow molecular mass distribution (M w/M n = 1.03−1.55) characterized by the absence of double bonds. It has been found that the molecular mass of oligomer products can be regulated by changing the molar ratio of the components of the catalytic system.

Use of the NiBr2(PPh3)2/Zn catalytic system for homo- and copolymerization of styrene and methyl methacrylate

The regularities of methyl methacrylate and styrene (co)polymerization in the presence of catalytic systems based on a Ni(II) complex combined with zinc and an aryl halide have been studied. The effects of temperature and catalytic system components on conversion are established. The molecular masses of the polymers linearly increase with monomer conversion, thus suggesting the controlled character of the polymerization. Reactivity ratios are calculated for methyl methacrylate-styrene copolymerization (rMMA = 0.45, rstyrene = 1.70) in the presence of NiBr2(PPh3)2/Zn/PhI. The rate of copolymerization is shown to decrease with an increase in methyl methacrylate concentration. The scheme of the process is proposed based on an analysis of the experimental and literature data.

Hydrodynamic and conformational properties of silicon-substituted addition-type polynorbornene macromolecules

Seven polynorbornene samples containing trimethylsilyl side groups that were prepared by the addition polymerization of 5-trimethylsilyl-2-norbornene in the presence of catalytic systems (π-C5H9NiCl)2-methylaluminoxane and nickel naphthenate-methylaluminoxane have been studied by translational isothermal diffusion and viscometry. The molecular masses of the polymer samples are measured. Kuhn-Mark-Houwink equations for diffusion coefficient D and intrinsic viscosity [η] are determined in toluene at 25°C: D = 6.94 × 10−4M−0.61 and [η] = 1.53 × 10−3M0.82. The equilibrium rigidity of polymers chains is estimated as A = 47 ± 9 A. The conformational features of the silicon-containing polynorbornene are analyzed by the PM3 quantumchemical semiempirical method on the basis of simulation of its decamer chain fragments. In terms of microstructure and equilibrium rigidity, the above-described addition poly(trimethylsilylnorbornene) is close to poly(trimethylsilylpropyne) synthesized using niobium pentachloride as a catalyst. This finding explains similar membrane gas-separation properties of these polymers.