Molecular Engineering in Homogeneous Catalysis:  One-Phase Catalysis Coupled with Biphase Catalyst Separation. The Fluorous-Soluble HRh(CO){P[CH₂CH₂(CF₂)₅CF₃]₃}₃ Hydroformylation System

Abstract

The hydroformylation of decene-1 was studied in the presence of the fluorous-soluble P[CH2CH2(CF2)5CF3]3 modified rhodium catalyst at 100 °C and 1.1 MPa of CO/H2 (1:1) in a 50/50 vol % toluene/C6F11CF3 solvent mixture, which forms a homogeneous liquid phase at and above 100 °C. P[CH2CH2(CF2)5CF3]3 was selected on the basis of a semiempirical calculation of the electronic properties of P[(CH2) x (CF2) y CF3]3 (x = 0, y = 2, 4 and x = 0−5, y = 2) and prepared by the reaction of PH3 with CH2CH(CF2)5CF3. The solution structure of HRh(CO){P[CH2CH2(CF2)5CF3]3}3 (1) in C6F11CF3 is similar to that of HRh(CO)(PPh3)3 (2) in toluene and HRh(CO){P(m-C6H4SO3Na)3}3 (3) in water. High-pressure NMR of 1 under 2.1−8.3 MPa of CO/H2 (1:1) revealed that 1 is in equilibrium with HRh(CO)2{P[CH2CH2(CF2)5CF3]3}2 (4). Kinetic studies show that the reaction is first order in both rhodium and decene-1. While the reaction is inhibited by P[CH2CH2(CF2)5CF3]3, the normal/iso (n/i) ratio of the aldehyde increases with increasing phosphine concentration. The catalytic activity of the Rh/P[CH2CH2(CF2)5CF3]3 catalyst is similar to that of the nonfluorous analogue Rh/P[(CH2)7CH3]3 catalyst and is an order of magnitude lower than that of the Rh/PPh3 catalyst. Surprisingly, the n/i product selectivity of Rh/P[CH2CH2(CF2)5CF3]3 is closer to the selectivity of the Rh/PPh3 catalyst than that of the Rh/P[(CH2)7CH3]3 catalyst. The fluorous biphase catalyst recovery concept was tested in a semicontinuous hydroformylation of decene-1 with the Rh/P[CH2CH2(CF2)5CF3]3 catalyst. During 9 consecutive reaction/separation cycles, a total turnover of more than 35 000 was achieved with a loss of 1.18 ppm of Rh/mol of undecanals. The fluorous-soluble Rh/P[CH2CH2(CF2)5CF3]3 catalyst was also tested for the continuous hydroformylation of ethylene using the high-boiling fluorous solvent FC-70, which allows continuous removal of propanal at the reaction temperature of 110 °C. The long-term stability of the Rh/P[CH2CH2(CF2)5CF3]3 catalyst is better than that of the Rh/PPh3 catalyst. Thus, the Rh/P[CH2CH2(CF2)5CF3]3 catalyst is the first catalyst system which can be used for the hydroformylation of both low and high molecular weight olefins and provides facile catalyst separation for both low and high molecular weight aldehydes.

Fluorous biphasic hydrogenation of 1-alkenes using novel fluorous derivatives of Wilkinson's catalyst

“…benzene at room temperature to produce 5a,b in essentially quantitative yield. All three complexes 5 were fully characterized by NMR spec-Ž 4 From the 31 P NMR data, it can be concluded that complexes 5 adopt square planar geometries similar to the original w x Wilkinson's catalyst 15 . Solubility studies with 5b in pure FC-72, n-hexane or benzene indicate that in contrast to the free fluorous phosphines, the fluorous rhodium complex 5b has high fluor phase solubility at room temperature despite its high molecular weight.…”

Pd(II)-dissolved in ionic liquids: a recyclable catalytic system for the selective biphasic hydrogenation of dienes to monoenes

“…Initial investigations were performed on the hydrogenation of 1,3-butadiene (80 mmol) by Pd(acac) 2 (0.08 mmol) dissolved in 3 mL of 1-n-butyl-3-methylimidazoilum tetrafluoroborate (BMI.BF 4 , liquid down to -81°C) 8f and in 3 mL of 1-n-butyl-3-methylimidazoilum hexafluorophosphate (BMI.PF 6 , liquid down to -61°C) 8f ionic liquids at 50°C (Scheme 1 and Table 1). …”

“…Amongst the "mobile" phases employed for the immobilization of transitionmetal catalyst precursors 3,4,6,7 molten salts are attracting increasing and continuous interest amongst academic and industrial chemists 8 . One asset of biphasic catalysis in ionic liquids is that it allows in various cases the direct transposition of known homogeneous one-phase reactions to two-phase systems without the synthesis of specially designed ligands and/or complexes.…”

Economia de átomos, engenharia molecular e catálise organometálica bifásica: conceitos moleculares para tecnologias limpas

“…Como a maioria das limitações envolvidas nesses processos têm sua origem a nível molecular, um novo campo interdisciplinar, denominado genericamente de engenharia molecular 6 , está emergindo com o objetivo de resolver esses problemas através de modificações estruturais do processo químico a nível molecular.…”

“…dificilmente o processo poderá ser rentável. A seguir, discutiremos os conceitos de economia atômica 3,4,5 e engenharia molecular 6 que abordam a eficiência máxima de um processo químico do ponto vista molecular. Além disso, apresentaremos e discutiremos os conceitos da catálise bifásica organometálica que vem demonstrando ser uma das melhores abordagens para a geração de processos com eficiência máxima.…”