New coordination catalysts based on rare earth compounds for polymerization of 1-octene

The study of rare earth coordination catalysts for polymerization of 1-octene has been successfully carried out for the first time. Some features and kinetic behavior of polymerization of 1-octene by Nd(naph)₃–AIEt₃ catalyst system in tetrachloro-methane are described. The overall polymerization activation energy E_a measured was 74.5 kJ/mol and the rate equation could be expressed as R_p = k_p [Nd] [M] (k_p = 3.21 × 10^?3 L/mol s, at 50°C). The catalytic activity of various rare earth elements in Ln (naph)₃ and ligands in NdL₃ for the polymerization was compared. A 1-octene oligomer with double bonds was obtained. It is either a white or pale yellow waxy semi-solid. Its number-average molecular weight is about 10³ and the molecular weight distribution is less than 2.     

Norbornene polymerization using multinuclear nickel catalysts based on a polypropyleneimine dendrimer scaffold

Four multinuclear nickel complexes derived from generation 1 (G1) and generation 2 (G2) dendrimeric salicylaldimine ligands based poly(propyleneimine) dendrimer scaffolds of the type, DAB-(NH₂)_n (n = 4 or 8, DAB = diaminobutane) were evaluated as catalysts precursors in the polymerization of norbornene, using methylaluminoxane as co-catalyst. All four catalyst evaluated were found to be active for norbornene polymerization giving polymers with moderate to high molecular weights and low polydispersity indices. The polymerization results indicate that there is some sort of dendritic effect, in that the catalyst activity appears to be influenced by the dendrimer generation.     

Synthesis of bis-(2-fluoro-2, 2-dinitroethyl) nitramine and tris-(2-fluoro-2,2-dinitroethyl) amine

Russian Chemical Bulletin -     

Polymerization of 1-octene and determination of markhouwink constants of poly(1-octene)

The polymerization of 1-octene initiated by methylalumoxane（MAO）-activated Ni（Ⅱ）-based-α-diimine complexes[（2,6-i-Pr）₂C₆H₃-DAB（An）]NiBr₂ was investigated.Using this catalyst,poly（1-octene）s with molecular weight between 100×10³ and 400×10³ and polydispersity（M_w/M_n） between 1.3 and 1.5 were synthesized successfully by varying reaction time at room temperature.The poly（1-octene）s were amorphous polymers and could be well soluble in tetrahydrofuran（THF）.After fractional precipitation,poly（1-octene）s with narrow molecular weight distributions（M_w/M_n≤1.12） were obtained.Their weight-average molecular weights were measured by gel permeation chromatography（GPC） in conjunction with online model BI-MwA multiangle laser light scattering（MALLS）,and their intrinsic viscosities were measured by Maron’s single-point method.The k and a values in Mark-Houwink equation[η]= KM^αin THF at 40℃were 0.089 mL/g and 0.61 respectively.     

Hydroformylation of alkenes employing rhodium(i) complexes and a phosphine oxide ligand

Following the facile synthesis of a novel phosphine oxide compound, (diphenylphosphinoyl)phenylmethanol (1), this compound was employed as a ligand in the rhodium-catalyzed hydroformylation of alkenes, with good conversions and regioselectivities. This ligand was partially resolved using an enzyme, and enantioselective hydroformylation was carried out with the addition of a rhodium(I) complex. The rhodium(I) complex containing ligand 1 was not isolated, although it was subjected to low-temperature NMR studies.     

The transient-chelating-group-controlled stereoselective Rh(i)-catalyzed silylative aminocarbonylation of 2-alkynylanilines: access to (Z)-3-(silylmethylene)indolin-2-ones

A new method involving mild acryl transient-chelating-group-controlled stereoselective Rh(i)-catalyzed silylative aminocarbonylation of 2-alkynylanilines with CO and silanes is presented for producing (Z)-3-(silylmethylene)indolin-2-ones. Upon using an acryl transient chelating group, 2-alkynylanilines undergo an unprecedented alkyne cis-silylrhodation followed by aminocarbonylation to assemble (Z)-3-(silylmethylene)indolin-2-ones. Mechanistic studies show that acryl transient chelating effects result in the key alkyne cis-silylrhodation process.

Transient-chelating-group-controlled stereoselective rhodium(I)-catalyzed silylative aminocarbonylation of 2- alkynylanilines with CO and silanes toward (Z)-3-(silylmethylene)indolin-2-ones is presented.     

Hydroformylation of vinylsilanes with Rh(acac)(CO)2/tris(N-pyrrolyl)phosphine catalytic system

Rh(acac)(CO)₂ as catalyst precursor with a small excess of free N-pyrrolylphosphine ([P(NC₄H₄)₃]:[Rh] = 3–10) was found to be very active in hydroformylation of vinyltrisubstituted silanes at 80 °C and 10 atm CO/H₂ = 1. After 2 h the yields of aldehydes were 80 % (n/iso = 8) for vinyltrimethylsilane, 100 % (only n-isomer) for vinyldimethylphenylsilane and 95 % (n/iso = 5.5) for vinyltrimethoxysilane. The rate of hydroformylation of vinyltrimethylsilane is ca. three times higher than that of other vinylsilanes. 3,3-Dimethyl-1-butene undergoes hydroformylation much slower than vinyltrimethylsilane probably because of its high steric hindrance and the reaction produces 4,4-dimethylpentanal as the only product.     

Detection of the chemical warfare agents bis-(2-chloroethyl)ethylamine (HN-1) and tris-(2-chloroethyl)amine (HN-3) in air.

This paper describes the method development and validation for detection of the chemical warfare agents HN-1 and HN-3 in air using C8 solid-phase extraction disks followed by liquid desorption and analysis by gas chromatography. The method is contrasted to the standard approach which uses solid sorbent tubes followed by thermal desorption and analysis by gas chromatography.     

Kinetics of polymerization of 1-octene with Mgcl2-supported Ticl4 catalysts

A number of TiCl₄ catalysts supported on MgCl₂ which was activated by the recrystallization method using different alcohols were prepared with ethyl benzoate or dibutyl phthalate as the internal electron donor. All the catalysts were characterized by BET, x-ray diffraction, and hydrolysis–GC analysis. Kinetics of polymerization of 1-octene was studied with three of the above catalysts (having different internal electron donors) activated by AlEt₃. The rate of polymerization increased linearly with increasing temperature, and catalyst and monomer concentrations. From the Arrhenius plot, the overall activation energies of polymerization were determined and the dependence of rate on the AlEt₃ concentration could be explained by the Langmuir-Hinshelwood mechanism. ¹³C-NMR was used to study the effect of internal electron donors on the % isotacticity of poly(1-octene). The catalytic activities of all the catalysts were compared in 1-octene polymerization. © 1994 John Wiley & Sons, Inc.     

Rh(111)及Rh@Cu(111)表面乙烯氢甲酰化反应选择性的理论研究

采用密度泛函理论对比研究了Rh(111)表面与Rh@Cu(111)表面合金上乙基加氢反应及CO插入反应过程.结果发现,与Rh(111)表面相比,Rh@Cu(111)表面合金的集团效应和配体效应使得加氢反应的能垒降低了0.12eV,而CO插入反应的却显著降低了0.78eV.这表明RhCu合金催化剂可以有效地提高氢甲酰化反应的选择性.     

9,9-二甲基-2-(N-联苯基)氨基芴的合成

以芴为原料,苄基三甲基三溴化铵为溴化试剂,室温下在甲醇和二氯甲烷中溴化得到2-溴芴,然后以四氢呋喃为溶剂,在叔丁醇钾作用下与碘甲烷反应合成9,9-二甲基-2-溴芴,最后与4-联苯胺通过Buchwald-Hartwig偶联反应合成目标化合物9,9-二甲基-2-(N-联苯基)氨基芴,总收率为56.0%～62.4%。通过1HNMR、13CNMR、MS、IR和元素分析确证了其结构。     

Binuclear carbonyl-containing complexes of Rh(i) with bis-(o-hydroxy)- and bis-(o-amino) quinones

Conclusions We synthesized a number of binuclear rhodium complexes that contain bis-(o-hydroxy)- and bis-(o-amino) quinones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2630–2632, November, 1973.     

杂双核Rh(I)-Cr配合物催化乙炔氢甲酰化反应机理的密度泛函研究

用密度泛函B3LYP方法对杂双核(CO)4Cr(μ-PH2)2RhH(CO)(PH3)配合物催化乙炔氢甲酰化反应机理进行了详细研究. 对结合和解离机理所涉及中间体和过渡态的结构进行详细分析, 在此基础上阐明了金属铬的协同性. 计算结果表明解离机理占主导地位. 乙炔氢甲酰化反应的决速步骤为炔烃插入步骤, 在298.15 K和101.325 kPa下的活化自由能为73.72 kJ/mol. 乙炔插入和醛还原消除步骤均在热力学上不可逆. Cr(CO)4部分的引入并没有改变乙炔氢甲酰化反应机理. Rh与Cr间的d轨道相互作用在反应过程起重要作用.     

Spektrophotometrische Untersuchung Der Wechselwirkung Zwischen Rh(III) und 1-(2-Thiazolylazo)-Resorzin

Abstract

It has been shown, that depending on the ratio of the concentration of Rh(III) and 1-(2-thiazolylazo)-resorcin and the pH there will be formed in solution at least two substances with different chemical and light absorption properties. The optimum conditions for the existence of each substance have been determined in addition to molar absorbtivities of the colored substances, the equilibrium constants for their formation, and their stability constants.