负载型非晶态Co-B催化剂在1-辛烯氢甲酰化中的应用

以醇凝胶-氮气热处理方法制备的ZrO2、碳纳米管(CNTs)及介孔分子筛SBA-15作为载体,采用化学还原法制备了负载型非晶态Co-B催化剂,利用粉末X射线衍射(XRD)、氮气吸附等温线、透射电子显微镜(TEM)、电感耦合等离子体-原子发射光谱(ICP-AES)以及X射线光电子能谱(XPS)等对催化剂进行了表征.以1-辛烯的氢甲酰化为目标反应,考察了负载型非晶态Co-B催化剂在氢甲酰化反应中的性能及循环使用效果.表征结果显示,以NaBH4为还原剂制备的负载型Co-B催化剂上的Co-B为非晶态,负载Co-B组分对载体的晶相结构没有影响.反应结果表明,在1-辛烯的氢甲酰化反应中,负载型非晶态Co-B催化剂都显示较高的初始活性.随着循环次数的增加,三种催化剂的活性下降,但下降幅度有所不同,Co-B/CNTs和Co-B/SBA-15的循环使用稳定性高于Co-B/ZrO2.     

聚钛氨烷-铑络合物催化环己烯的醛化反应

用聚钛氨烷-铑络合物催化环己烯的醛化,以很高的收率得到了环己基甲醛。     

担载Ru-Co原子簇催化剂在乙烯甲酰化中的催化行为

众所周知，催化活性和选择性与活性组分的粒度、结构有很大的关系，而通过金属有机原子簇化合物载于无机载体上可以获得金属高分散度和金属组分组成均匀的催化剂，在一系列反应中显示了较高的活性和选择性[1-3]．在前面的研究中，肖丰收等报导了担载的Ru－CO双金属原子簇催化剂在CO＋H2反应中对含氧化合物的形成显示了很高的活性和选择性[4-5]．在本文中，作者利用红外光谱等技术研究了在SiO2担载的Ru－Co双金属原子簇催化剂上乙烯甲酸化反应，并对含氧化合物的形成机理进行了讨论．1实验部分在催化剂的制备过程中所有的操作都是在高纯…     

四膦配体的合成及其金属配合物催化烯烃氢甲酰化反应研究

合成了四膦配体Ｃ（ＣＨ２ＰＰｈ２）４，并研究了由钴－四膦配体组成的催化剂体系对烯烃氢甲酰化反应的催化作用．对反应的各种因素，如反应温度、反应压力、不同Ｐ／Ｃｏ比，不同烯烃等的影响作了探讨，并与不同膦配体体系催化烯烃氢甲酰化作对比，发现膦配体催化活性有如下顺序：Ｃ（ＣＨ２ＰＰｈ２）４≈Ｐｈ２Ｐ（ＣＨ２）２ＰＰｈ２＞Ｐｈ２Ｐ（ＣＨ２）３ＰＰｈ２＞Ｐｈ２ＰＣＨ２ＰＰｈ２＞Ｐｈ２Ｐ（ＣＨ２）４ＰＰｈ２．     

Phosphinoethyl-sulfonatoalkylthioethers and diphenyl-ω-sulfonatoalkyl-phosphines as ligands and polyoxyethylene–polyoxypropylene–polyoxyethylene triblock co-polymers as promoters in the rhodium-catalyzed hydroformylation of 1-dodecene in aqueous two-phase systems

The rhodium-catalyzed hydroformylation of 1-dodecene was investigated with a series of sulfonated water-soluble phosphine ligands at a pressure of 60 bar CO/H₂ and a temperature of 120 °C. Seven different groups of water-soluble phosphines were used for our investigations. We established an optimized ligand/rhodium ratio of 5 for the phosphines 1a, [Ph₂P(CH₂)₂S(CH₂)₂SO₃Na], and 1b, [Ph₂P(CH₂)₂S(CH₂)₃SO₃Na]. The utilized arylphosphino-thioether-alkylsulfonates formed with Rh(I) compounds highly active catalysts which could be recycled. The addition of detergents speeds up the hydroformylation reaction, but disturbs the phase separation (recycling). The best promotion effect and the smallest negative influence on phase separation gave polyoxyethylene–polyoxypropylene–polyoxyethylene triblock co-polymers. The ratio of 1-dodecene/rhodium could be increased up to 10.000 and we achieved turnover numbers (TONs)>50.000 without any surfactant and TONs of about 65.000 in presence of the co-polymers owing to the recycling on the catalytic system.     

α-Fluorinated cyclic amidophosphite ligands. Their synthesis, Rh complexes and catalytic activity in the hydroformylation of styrene

The synthetic approaches to cyclic phosphite and amido(diamido)phosphite ligands bearing the residues of electron withdrawing perfluorinated tails at the β-position to the phosphorus atom have been elaborated. Catalytic systems based on rhodium complexes of these ligands formed in situ using Rh(CO)₂(acac) as a catalytic precursor demonstrate high activity in the hydroformylation of styrene along with good selectivity in respect to branched aldehyde. Quantum-chemical calculations proved that both the rate of the formation of branched alkyl complex, as well as its reactivity are influenced by the steric and electronic parameters in the same manner.     

Mechanistic studies on the formation of Pt(II) hydroformylation catalysts in imidazolium-based ionic liquids

The kinetics of the formation of the active species cis-[Pt^II(PPh₃)₂Cl(SnCl₃)] and cis-[Pt^II(PPh₃)₂(SnCl₃)₂] from the hydroformylation catalyst precursor cis-[Pt^II(PPh₃)₂Cl₂] in the presence of SnCl₂, was studied in two different imidazolium-based ionic liquids. A large range of different chlorostannate melts consisting of 1-butyl-3-methyl-imidazolium cations and [Sn_xCl_y]^{(−y + 2x)} anions with varying molar fraction of SnCl₂, were prepared and characterized by ¹H and ¹¹⁹Sn NMR. The observed chemical shifts point to major changes in the composition of the anionic species within the melt. The second ionic liquid employed, viz., 1-butyl-3-methyl-imidazolium-bis(trifluormethylsulfonyl)amide was prepared in a colorless quality that enabled its application in kinetic studies. The concentration and temperature dependence of the substitution of Cl⁻ by [SnCl₃]⁻ to yield cis-[Pt^II(PPh₃)₂Cl(SnCl₃)], could be studied in detail. Theoretical (DFT) calculations were employed to model the reaction progress and to resolve the role of the ionic liquid in the activation of the catalyst. The available results are presented and a plausible mechanism for the formation of the catalytically active species is suggested.     

Synthesis and characterisation of two novel Rh(I) carbene complexes: Crystal structure of [Rh(acac)(CO)(L1)]

The [Rh(acac)(CO)(L)] (acac = acetylacetonato; L₁ = 1,3-bis-(2,6-diisopropylphenyl)imidazolinylidene and L₂ = 1,3-bis-(2,4,6-trimethylphenyl)imidazolinylidene) complexes were prepared by the action of the parent carbene on [Rh(acac)(CO)₂] in THF. The crystal structure characterisation of [Rh(acac)(CO)(L₁)] revealed a slightly distorted square planar geometry with the carbene ligand orientated almost perpendicular to the equatorial plane; an elongated trans Rh-O bond of 2.0806(18) Å reflecting the considerable trans-influence of the carbene ligand. By measuring the CO stretching frequencies in a range of [Rh(acac)(CO)(L)] complexes (L = CO, L₁, L₂, PPh₃, PⁿBu₃, P(O-2,4-^tBu₂-Ph)₃) the following electron donating ability series was established: L₁ ∼ L₂ ∼ PⁿBu₃ > PPh₃ > P(O-2,4-^tBu₂-Ph)₃ > CO; indicating the carbenes investigated in this study to have a similar electronic cis-influence as trialkyl phosphines. Both complexes do not display hydroformylation activity towards 1-hexene in the absence of added phosphine or phosphite ligands under the conditions investigated (P = 60; T = 85 °C). In the presence of a phosphine or phosphite ligand the resulting hydroformylation catalysis was identical to that observed for [Rh(acac)(CO)₂] and the corresponding ligand and subsequent high-pressure ³¹P NMR studies confirmed substitution of the carbene ligand under these conditions.     

Calix[4]arene‐based Bis‐phosphonites,Bis‐phosphites,and Bis‐O‐acyl‐phosphites as Ligands in the Rhodium(I)‐catalyzed Hydroformylation of 1‐Octene

New calix[4]arene‐based bis‐phosphonites, bis‐phosphites and bis‐O‐acylphosphites were synthesized and characterized. Treatment of these P‐ligands with selected rhodium and platinum precursors led to mononuclear complexes that were satisfactorily characterized. The solid state structure of the dirhodium(I) complex 14 has been determined by X‐ray diffraction. The two rhodium centres are bridged by two chloro ligands; one rhodium atom is further coordinated by calix[4]arene phosphorus atoms and the other by cyclooctadiene. The new calix[4]arene P‐ligands were tested in the Rh(I) catalyzed hydroformylation of 1‐octene. All Rh(I) complexes catalyzed the reaction leading to high chemoselectivity with regard to the formation of aldehydes. Yields and n/iso‐selectivities depended on the reaction conditions. Average yields of 80 % and n/iso‐ratios of about 1.3 to 1.5 were observed. High yields of aldehydes can be achieved using the methoxy substituted P‐ligands at low Rh:ligand ratios.