新型水溶性配体-负载金属氢甲酰化催化剂:TPPTS-Rh/SiO2

考察了几种硅胶负载贵金属催化剂和HRhCO(TPP) 3 催化剂的 1 己烯氢甲酰化反应 ,对Rh/SiO2 、HRhCO(TPPTS) 3 /SiO2 和TPPTS Rh/SiO2 上的 1 己烯氢甲酰化结果进行了比较 .结果表明 ,TPPTS Rh/SiO2 催化剂的醛的选择性和醛的正异比n/b接近HRhCO(TPPTS) 3 /SiO2 的相应的催化性能 ,而远高于Rh/SiO2 的相应的催化性能 ,7.0MPa高压下TPPTS Rh/SiO2 催化剂的活性大幅度增加 ,达到 0 .0 6 92S-1.实验排除了其他可能 ,认为是含有孤对电子的TPPTS和Rh/SiO2 中高度分散的Rh粒子产生了化学键的作用 ,形成了具有匀相性能的支撑水膜多相催化剂 :TPPTS Rh/SiO2 .     

Domino reaction sequences in the rhodium-catalyzed hydroformylation of 3-acetyl-1-allylpyrrole: a short route to 5,6,7,8-tetrahydroindolizines

When 3-acetyl-1-allylpyrrole (1) was subjected under hydroformylation conditions, with Rh₄(CO)₁₂ as catalyst precursor, to 30 atm CO/H₂ (1:1) total pressure and 140 °C, an equimolar mixture of the isomeric 5,6,7,8-tetrahydroindolizines 4′ and 5′ was obtained as the almost exclusive product. In both cases a domino hydroformylation/cyclization on the α pyrrole positions by the aldehyde 3 carbonyl group occurs which involves different intermediates: while 4′ is generated via the dihydroindolizine 4, 5′ forms via direct reduction of 8-hydroxytetrahydroindolizine 5, a structure that has never been observed before from 1-allylpyrroles under oxo conditions.     

Hydroformylation of alkyl alkenes catalyzed by rhodium supported on MCM-41: The effect of H3PW12O40 on the catalytic activity and recycling

Heteropolyacids impregnated with rhodium(I) or (III) complexes were prepared and used as supported catalysts in the hydroformylation of alkyl alkenes. Two general types of catalysts were prepared and tested: rhodium(I) or (III) in the presence and in the absence of the heteropolyacid H₃PW₁₂O₄₀, 25H₂O (adopted as HPW₁₂) supported on MCM-41 (30 Å). 1-Octene was chosen as a model substrate. Different types of supported catalysts were tested in the hydroformylation of 1-octene and other alkyl alkenes. The effects of the temperature and the type of solvent on the reaction were studied. The results showed that the supported catalysts containing the heteropolyacid H₃PW₁₂O₄₀, 25H₂O (HPW₁₂) along with rhodium(I) or (III) gave higher catalytic activity. In addition, the recycling of the supported catalysts was studied and the results showed again the important effect of the presence of HPW₁₂ on the recycling of the rhodium catalysts.     

Rhodium-tris(3,5-bis(trifluoromethyl)phenyl)phosphine catalyzed hydroformylation of dienes to dialdehydes in supercritical carbon dioxide with high activity

Rhodium-catalyzed hydroformylation of 1,5-hexadiene and 1,7-octadiene to corresponding dialdehydes was investigated in compressed CO₂ and in toluene using different fluorinated phosphine compounds as ligands. A rhodium complex using tris(3,5-bis(trifluoromethyl)phenyl)phosphine is highly effective in compressed CO₂ for double hydroformylation of 1,5-hexadiene, whose TOF value is much larger than those reported so far. It has been shown that this ligand is effective also for the hydroformylation of 1,7-octadiene and scCO₂ is a better solvent than a conventional organic solvent of toluene for the title reaction.     

Supraphos: A supramolecular strategy to prepare bidentate ligands

Herein, we report a new strategy for the preparation of chelating bidentate ligands, which involves the mixing of two mondentate ligands functionalized with complementary binding sites. The assembly process is based on selective metal-ligand interactions employing phosphite zinc(II) porphyrins 1-6 and the nitrogen-containing phosphorus ligands b-i (Scheme 1). Only 14 monodentate ligands were utilized to generate a library of 48 palladium catalysts based on supraphos-type bidentate ligands. The characterization of rhodium complexes based on representative Supramolecular bidentate ligands and the comparison of their performance in the hydroformylation of styrene will be presented. The current library of catalysts was tested in the asymmetric palladium-catalyzed alkylation of rac-1,3-diphenyl-2-propenyl acetate, which resulted in a large variety in the observed enantioselectivity for the different catalysts. Importantly, small variations in the supraphos building blocks, lead to large differences in the enantioselectivity imposed by the catalyst, the most selective catalyst producing 97% ee.     

Microwave assisted hydroaminomethylation of alkenes

Hydroaminomethylation of terminal alkenes can be regioselectively carried out in less than 30 min with secondary amines in EtOH under MW irradiation using (PPh₃)₃RhCO(H) and Xantphos or Biphephos as ligands. When primary amines were employed, the corresponding enamines were obtained in good yields. Tris-benzyl allylglycine was transformed into different (basic) benzylated α-amino acids. Moreover, the benzyl protection was removed in few minutes under MW irradiation with Pd(OH)₂ under H₂ atmosphere.     

有机膦配位催化剂的结构与活性关系 Ⅶ．碱性添加剂作用的原位红外光谱研究

本文报导了应用加压原位红外光谱技术考察ＫＯＨ添加剂对钴－膦催化剂平衡系统的组成及催化活性物种的影响．结果表明，羧酸钴─三烷基膦组成的二元体系催化剂在烯烃氢甲酰化条件下生成了游离的羧酸使烯烃异构化副反应增加．添加适量的ＫＯＨ，组成钴－膦－钾三元体系催化剂，中和了部分游离羧酸，使烯烃异构化副反应显著减少．但是ＫＯＨ过量时，在催化剂平衡体系中生成较多的非活性的［Ｃｏ（ＣＯ）_４］－离子，使催化活性物种ＨＣｏ（ＣＯ）_３Ｌ的浓度明显减少．从而降低了高碳醇的生成速度．     

Domino hydroformylation-Wittig olefination-hydrogenation

Rhodium-catalyzed hydroformylation in the presence of stabilized phosphorus ylides initiates a domino hydroformylation-Wittig olefination process. When mono-substituted acceptor-stabilized phosphorus ylides were employed, a hydrogenation step succeeds the Wittig olefination to give a domino hydroformylation-Wittig olefination hydrogenation process. For the hydroformylation key step both, linear regioselective hydroformylation of terminal alkenes based on catalyst control as well as diastereoselective hydroformylation based on ortho-diphenylphosphanylbenzoate (o-DPPB)-directed active substrate control could be employed.     

载体及活性组份对聚合物负载铑络合物的催化醛化性能和稳定性的影响

本文研究了载体和活性组份(包括载体交联度、孔径、比表面及铑负载量等因素)对聚合物负载铑络合物在己烯-1氢甲酰化反应中的催化性能与稳定性的影响。     

担载金属簇——Ⅰ.硅胶化学键联羰基钴簇YCCo_3(CO)_9催化剂

羰基钴簇络合物YCCo_3(CO)_9,是一种具有良好醛化活性的均相催化剂。本文报导将它化学键联到硅胶表面上而固相化,及其醛化反应评价结果。首先由C_2H_3Si(EtO)_3合成CCl_3C_2H_4Si(EtO)_3,然后将此化合物与硅胶表面键联。生成三氯化物,再与八羰基二钴反应而制得负载型催化剂,其钴含量为6～7％。测定了此负载型催化剂的红外光谱,评价其对庚烯-1的醛化反应活性。发现在140℃,40公斤/厘米~2压力的较佳反应条件下,6小时内,庚烯-1转化率为83％,而醇醛选择性92％。此外还进行了多次循环使用试验,但其钴流失似仍过大。