New method for the synthesis of 1,4-enynes by the cross-coupling of magnesium acetylides with allyl compounds

Conclusions A method was developed for the synthesis of 1,4-enynes by the cross-coupling of compounds of type (RCC)₂Mg and RCCMgBr with allyl alcohol derivatives using Ni(acac)₂-Ph₃P as the catalyst.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 907–908, April, 1984.     

Reactions of Aluminium Tribromide with Tetrakis(triphenylphosphine)nickel(0) and Tetrakis(triethylphosphite)nickel(0) Complexes

Reactions of aluminium tribromide with the Ni(0) phosphine and phosphite complexes are studied by EPR method. AlBr₃was found to cause the oxidation of the transition metal in the (PPh₃)₄Ni complex to the univalent state with the formation of the tetracoordinated (PPh₃)₃NiBr complex. With an excess of AlBr₃, the phosphine ligands are eliminated from the coordination sphere of Ni(I), and the coordinatively unsaturated complexes are destroyed to give the colloidal nickel. In the reaction of (P(OEt)₃)₄Ni with AlBr₃, Ni(0) is also oxidized to Ni(I), but the acido ligand is not eliminated even with a 15-fold excess of the Lewis acid. The activity of catalytic systems on the basis of the Ni(0) phosphine complexes and the Lewis acids in the low-molecular oligomerization reactions of olefines is determined by the cationic coordinatively unsaturated Ni(I) complexes formed in these systems.     

Nature of the activity and the kinetics of cyclohexene hydrogenation by the catalytic system (C5H5)2 TiCl2?LiC4H9

The reaction of tributylphosphine with the catalytic system (C₅H₅)₂ TiCl₂–LiC₄H₉ prepared in an atmosphere of H₂ has been investigated in toluene solution. By using the ESR technique, a hydride complex Cp₂Ti(H) (PBu₃) has been detected. The proportionality between the rate of cyclohexene hydrogenation and the complex concentration has been established. The kinetics of cyclohexene hydrogenation has been investigated and a reaction mechanism is proposed.

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Cp₂TiCl₂–LiC₄H₉ (Cp–C₅H₅), H₂, Cp₂Ti(H) (PBu₃). Ti (III). .

     

Structure of the Mo-Containing Dispersed Catalyst During Heavy Oil Upgrading in the Presence of Steam And Hydrogen

XRD, TEM, EXAFS/XANES methods are first used to study the structure and morphology of Mocontaining phases of carbon residues of heavy oil refining during catalytic steam cracking, catalytic cracking without water, and hydrocracking. According to the results obtained from physical and chemical studies of Mo-based catalytic phases, the reaction medium affects structural features of Mo-containing phases, e.g. the amount of oxide and sulphide forms, the particle size, and particle morphology.     

Study of the nature and mechanism of the formation of paramagnetic species in nickel-based Brookhart-type catalytic systems

The catalytic systems NiBr₂(DPP-DAB) + 20 MAO and NiBr₂(DPP-BIAN) + 20 MAO (DPP-BIAN = bis(2,6-diisopropylphenyl)-bis(imino)-acenaphtene, MAO = methylaluminoxane), as well as a number of model systems, are studied under conditions of their activation and functioning. There are paramagnetic nickel complexes and radical-anion aluminum complexes in the systems under real conditions of activation and functioning. The highest activity is observed when the Ni(I) signal intensity in the ESR spectrum is maximal. A mechanism of paramagnetic species formation is proposed.     

CHEMICAL STRUCTURE AND FUNCTIONAL PROPERTIES OF AMORPHOUS BORON CARBONITRIDE FILMS

Journal of Structural Chemistry - We report a comprehensive study of the effect of the chemical structure of boron carbonitride films on the variability of their functional characteristics. The...