Cobalt catalyzed hydroformylation of higher olefins in the presence of chemically modified cyclodextrins

The cobalt catalyzed hydroformylation of higher olefins in the presence of chemically modified cyclodextrins was investigated in an aqueous biphasic system. The effect of various parameters, such as the nature of the cyclodextrin and olefin, the temperature, the CO/H₂ pressure, the concentration of the cyclodextrin and TPPTS was studied. The results demonstrate that the partially methylated β-cyclodextrin gives good conversion (>92%) and selectivity (>92%) for the hydroformylation of higher olefins without impeding the recovery of the catalytic system.     

Phenoxaphosphino‐Modified Xantphos‐Type Ligands in the Rhodium‐Catalysed Hydroformylation of Internal and Terminal Alkenes

The solubility of the modifying ligand is an important parameter for the efficiency of a rhodium‐catalysed hydroformylation system. A facile synthetic procedure for the preparation of well‐defined xanthene‐type ligands was developed in order to study the influence of alkyl substituents at the 2‐, and 7‐positions of the 9,9‐dimethylxanthene backbone and at the 2‐, and 8‐positions of the phenoxaphosphino moiety of ligands 1 – 16 on solubility in toluene and the influence of these substituents on the performance of the ligands in the rhodium‐catalysed hydroformylation. An increase in solubility from 2.3 mmol⋅L⁻¹ to >495 mmol⋅L⁻¹ was observed from the least soluble to the most soluble ligand. A solubility of at least 58 mmol⋅L⁻¹ was estimated to be sufficient for a large‐scale application of these ligands in hydroformylation. Highly active and selective catalysts for the rhodium‐catalysed hydroformylation of 1‐octene and trans‐2‐octene to nonanal, and for the hydroformylation of 2‐pentene to hexanal were obtained by employing these ligands. Average rates of >1600 (mol aldehyde) × (mol Rh)⁻¹×h⁻¹ {conditions: p(CO/H₂) = 20 bar, T = 353 K, [Rh] = 1 mM, [alkene] = 637 mM} and excellent regio‐selectivities of up to 99% toward the linear product were obtained when 1‐octene was used as substrate. For internal olefins average rates of >145 (mol aldehyde)×(mol Rh)⁻¹×h⁻¹ {p(CO/H₂) = 3.6–10 bar, T = 393 K, [Rh] = 1 mM, [alkene] = 640–928 mM} and high regio‐selectivities up to 91% toward the linear product were obtained.     

Rhodium‐Catalyzed Highly Regioselective Hydroformylation‐Hydrogenation of 1,2‐Allenyl‐Phosphine Oxides and ‐Phosphonates

The rhodium‐catalyzed hydroformylation‐hydrogenation of 1,2‐allenyl‐phosphine oxides and ‐phosphonates is reported in this paper. The regioselectivity was well controlled, affording only saturated linear γ‐phosphinyl aldehydes under the standard conditions: (carbonyl)tris(triphenylphosphine)‐rhodium hydride [RhH(CO)(PPh₃)₃] (3 mol%), triphenylphosphine (PPh₃) (10 mol%), carbon monoxide (CO) (2.4×10⁶ Pa), hydrogen (H₂) (subsequently charged to 4.8×10⁶ Pa), toluene, 100 °C, 24 h.     

Heptakis(2,3‐di‐O‐methyl‐6‐O‐sulfopropyl)‐β‐cyclodextrin: A Genuine Supramolecular Carrier for Aqueous Organometallic Catalysis

The behavior of heptakis(2,3‐di‐O‐methyl‐6‐O‐sulfopropyl)‐β‐cyclodextrin as inverse phase transfer catalyst in biphasic Tsuji–Trost and hydroformylation reactions has been investigated. In terms of activity, this methylated sulfopropyl ether β‐cyclodextrin is much more efficient than the randomly methylated β‐cyclodextrin, which was the most active cyclodextrin known to date. From a selectivity point of view, the intrinsic properties of the catalytic system are fully preserved in the presence of this cyclodextrin as the chemo‐ or regioselectivity was found to be identical to that observed without a mass transfer promoter in the hydroformylation reaction. The efficiency of this cyclodextrin was attributed to its high surface activity and to the absence of interactions with the catalytically active species and the water‐soluble phosphane used to dissolve the organometallic catalyst in the aqueous phase.     

Aqueous Biphasic Hydroformylation Catalysed by Protein‐Rhodium Complexes

The water‐soluble complex derived from Rh(CO)₂(acac) and human serum albumin (HSA) proved to be efficient in the hydroformylation of several olefin substrates. The chemoselectivity and regioselectivity were generally higher than those obtained by using the classic catalytic systems like TPPTS‐Rh(I) (TPPTS=triphenylphosphine‐3,3′,3″‐trisulfonic acid trisodium salt). Styrene and 1‐octene, for instance, were converted in almost quantitative yields into the corresponding oxo‐aldehydes at 60 °C and 70 atm (CO/H₂=1) even at very low Rh(CO)₂(acac)/HSA catalyst concentrations. The possibility of easily recovering the Rh(I) compound makes the system environmentally friendly. The circular dichroism technique was useful for demonstrating the Rh(I) binding to the protein and to give information on the stability in solution of the catalytic system. Some other proteins have been used to replace HSA as complexing agent for Rh(I). The results were less impressive than those obtained using HSA and their complexes with Rh(I) were much less stable.     

Two‐Phase Hydroformylation of Higher Olefins Using Randomly Methylated α‐Cyclodextrin as Mass Transfer Promoter: A Smart Solution for Preserving the Intrinsic Properties of the Rhodium/Trisulfonated Triphenylphosphine Catalytic System

The two‐phase hydroformylation of higher olefins with the rhodium/trisulfonated triphenylphosphine catalytic system in the presence of various chemically modified α‐cyclodextrins has been investigated. These cyclodextrins allowed us to increase greatly the reaction rate and the chemoselectivity of the reaction but, contrary to what has been observed previously with the chemically modified β‐cyclodextrins, the linear to branched aldehydes ratio was not affected by the presence of α‐cyclodextrin derivatives. Indeed, the latter was found to be similar to that obtained without any mass transfer promoter, suggesting that the catalytic species are stable in the presence of α‐cyclodextrin derivatives.     

Rhodium catalyzed hydroformylation of 1-octene in microemulsion: comparison with various catalytic systems

In this work, we describe how addition of alkylpolyglycol ether type nonionic surfactant affects the hydroformylation of 1-octene in the presence of phosphine modified rhodium catalyst. Influence of different process parameters such as ligand excess and amount of surfactant on the reaction rate and selectivity were discussed. Direct comparison of microemulsion systems with classic processes was achieved by performing the reactions under comparable homogeneous and biphasic conditions. Thus, the experiments were carried out using catalysts such as unmodified rhodium carbonyl HRh(CO)₄ and HRh(CO)(PPh₃)₃ in homogeneous system, Rh–TPPTS complex in two-phase system and in association with co-solvent.     

Hydroformylation with rhodium phosphine-modified catalyst in a microemulsion: comparison of organic and aqueous systems for styrene, cyclohexene and 1,4-diacetoxy-2-butene

Use of microemulsion as a reaction media in the hydroformylation of different alkenes, namely styrene, cyclohexene and 1,2-diacetoxy-2-butene have been studied using alkylpolygylcol ether-type nonionic surfactant in the presence of phosphine-modified rhodium catalyst. The combination of the experiments under comparable homogeneous and biphasic conditions were performed in order to make direct comparison of microemulsion with classical systems. Thus, the experiments were also carried out using catalysts such as unmodified rhodium carbonyl H Rh(CO)₄ and H Rh(CO)(PPh₃)₃ in homogeneous system, Rh–TPPTS complex in two-phase system and in association with co-solvent.     

水溶性铑-膦络合物催化烯烃氢甲酰化反应--阳离子表面活性剂的加速作用

介绍了以水溶性铑-膦络合物RhCl(CO)(TPPTS)₂作为催化剂前体在水/有机两相体系中催化烯烃氢甲酰化反应研究的进展,阐述了阳离子表面活性剂的加速作用和介稳态胶束-离子对协同作用机理关系.通过两相体系中界面分子组装和选择与烯烃分子链长相匹配的表面活性剂, 设计制备了高区域选择性复合催化剂体系.当采用双长链表面活性剂与铑-膦络合物组成的复合催化体系时,在不搅拌的情况下就显示出极高的催化活性.     

Synthesis,Rhodium Complexes and Catalytic Applications of a New Water‐Soluble Triphenylphosphane‐Modified β‐Cyclodextrin

A new triphenylphosphane based on a β‐cyclodextrin skeleton (PM‐β‐CD‐OTPP) was synthesized. This ligand can be dispersed in water by using the nanoprecipitation method. Transmission electron microscopy and NMR spectroscopy showed that PM‐β‐CD‐OTPP is aggregated in water and forms a stable dispersion. Its aqueous solubility can be dramatically increased in the presence of selected water‐soluble guests by formation of inclusion complexes. Associated to a rhodium precursor, PM‐β‐CD‐OTPP is able to generate soluble rhodium species in water. In addition, NMR experiments showed that the cyclodextrin cavity remains accessible for a guest even when PM‐β‐CD‐OTPP is coordinated to rhodium. Finally, this ligand was efficient for rhodium‐catalyzed hydrogenation and hydroformylation performed in aqueous medium.     

The beneficial effect of alkali metal salt on supported aqueous-phase catalysts for olefin hydroformylation

Alkali metal salt modified SAP (supported aqueous-phase) rhodium catalysts prepared by coimpregnation method using alkali metal chloride were found to be active and selective for olefin hydroformylation. The salt addition promoted the formation of aldehydes with high selectivity, the aldehyde yield being increased more than 2.5 times at a proper salt/Rh ratio. Changes in stretching frequency of the carbonyl species were detected during ethene hydroformylation, which appeared at ca. 1625 cm^–1 on the non-modified SAP catalyst sample, while at ca. 1586 cm^–1 on the KCl-modified one, as shown by in situ IR spectroscopy. The results of a deuterium isotope effect experiment showed that the hydroformylation rate for aldehyde formation on SAP rhodium catalyst under atmospheric pressure of CO/D₂ was about 1.3 times faster than that under CO/H₂, implying that the rate-determining step involved in aldehyde formation is most probably a step related with hydrogen. The role of the alkali metal salt is discussed in relation with the reaction mechanism.     

Rhodium‐Catalyzed Tandem Isomerization/Hydroformylation of the Bio‐Sourced 10‐Undecenenitrile: Selective and Productive Catalysts for Production of Polyamide‐12 Precursor

The hydroformylation of 10‐undecenenitrile ( 1 ) – a substrate readily prepared from renewable castor oil – in the presence of rhodium‐phosphane catalysts systems is reported. The corresponding linear aldehyde ( 2 ) can be prepared in high yields and regioselectivities with a (dicarbonyl)rhodium acetoacetonate‐biphephos [Rh(acac)(CO)₂‐biphephos] catalyst. The hydroformylation process is accompanied by isomerization of 1 into internal isomers of undecenenitrile ( 1‐int ); yet, it is shown that the Rh‐biphephos catalyst effectively isomerizes back 1‐int into 1 , eventually allowing high conversions of 1 / 1‐int into 2 . Recycling of the catalyst by vacuum distillation under a controlled atmosphere was demonstrated over 4–5 runs, leading to high productivities up to 230,000 mol ( 2 )⋅mol (Rh)⁻¹ and 5,750 mol ( 2 )⋅mol (biphephos)⁻¹. Attempted recycling of the catalyst using a thermomorphic multicomponent solvent (TMS) phase‐separation procedure proved ineffective because the final product 2 and the Rh‐biphephos catalyst were always found in the same polar phase. Auto‐oxidation of the linear aldehyde 2 into the fatty 10‐cyano‐2‐methyldecanoic acid ( 5 ) proceeds readily upon exposure to air at room temperature, opening a new effective entry toward polyamide‐12.

     

Ab initio energy calculations and macroscopic rate modeling of hydroformylation of higher alkenes by Rh‐based catalyst

Ab initio quantum chemical computations have been done to determine the energetics and reaction pathways of hydroformylation of higher alkenes using a rhodium complex homogeneous catalyst. Calculation of fragments of the potential energy surfaces of the HRh(CO)(PPh₃)₃‐catalyzed hydroformylation of 1‐decene, 1‐dodecene, and styrene were performed by the restricted Hartree‐Fock method at the second‐order MØller‐Plesset (MP2) level of perturbation theory and basis set of 6‐31++G(d,p). Geometrically optimized structures of the intermediates and transition states were identified. Three generalized rate models were developed on the basis of above reaction path analysis as well as experimental findings reported in the literature. The kinetic and equilibrium parameters of the models were estimated by nonlinear least square regression of available literature data. The model based on H₂‐oxidative addition fitted the data best; it predicts the conversion of all the alkenes quite satisfactorily with an average deviation of 7.6% and a maximum deviation of 13%. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Sulfobutyl Ether‐β‐Cyclodextrins: Promising Supramolecular Carriers for Aqueous Organometallic Catalysis

The potentialities of sulfobutyl ether‐β‐CDs derivatives as supramolecular carrier in a biphasic Tsuji–Trost reaction catalyzed by a water‐soluble palladium complex of trisulfonated triphenylphosphine have been investigated. The efficiency of these cyclodextrins (CDs) strongly depends on the average molar substitution degree of cyclodextrin and the highest rate enhancements were obtained with cyclodextrins containing about 7 sulfobutyl ether groups. This result was attributed to the absence of a strong interaction between this cyclodextrin and the trisulfonated triphenylphosphine used to dissolve the catalyst in the aqueous phase and to the presence of an extended hydrophobic cavity allowing a better molecular recognition between the substrate and the cyclodextrin. This constitutes the first example of a non‐interacting β‐cyclodextrin/phosphine couple with high catalytic activities.     

Continuous Gas‐Phase Hydroformylation of 1‐Butene using Supported Ionic Liquid Phase (SILP) Catalysts

The concept of supported ionic liquid phase (SILP) catalysis has been extended to 1‐butene hydroformylation. A rhodium‐sulfoxantphos complex was dissolved in [BMIM][n‐C₈H₁₇OSO₃] and this solution was highly dispersed on silica. Continuous gas‐phase experiments in a fixed‐bed reactor revealed these SILP catalysts to be highly active, selective and long‐term stable. Kinetic data have been acquired by variation of temperature, pressure, syngas composition, substrate and catalyst concentration. A linear dependency in rhodium concentration could be established over a large concentration range giving another excellent hint for truly homogeneous catalysis in the SILP system. Compared to former studies using propene, the SILP system showed significantly higher activity and selectivity with 1‐butene as feedstock. These findings could be elucidated by solubility measurements using a magnetic microbalance.     

Selectivity of Rhodium‐Catalyzed Hydroformylation of 1‐Octene during Batch and Semi‐Batch Reaction using Trifluoromethyl‐Substituted Ligands

The regioselectivity of catalysts generated in situ from dicarbonyl rhodium(I)(2,4‐pentanedione) and trifluoromethyl‐substituted triphenylphosphine ligands has been evaluated during the hydroformylation of 1‐octene. The influence of batch or semi‐batch operation, the solvent, and the number of trifluoromethyl substituents has been investigated. During batch operation in a supercritical carbon dioxide (CO₂)‐rich system the differential n:iso ratio increases from approximately 4 to a value of 12–16 at about 90–95 % conversion for the catalyst based on bis[3,5‐bis(trifluoromethyl)phenyl]phenylphosphine. For semi‐batch conditions using hexane a constant n:iso ratio is obtained over a broad conversion range. Batch hydroformylation in neat 1‐octene is faster than in a supercritical CO₂‐rich, one‐phase system, with a similar overall selectivity as observed in the supercritical case. The results provide further directions for the development of ligands that are especially designed for the separation of homogeneous catalysts in continuously operated hydroformylation in scCO₂.     

Biphasic Aqueous Organometallic Catalysis Promoted by Cyclodextrins: How to Design the Water‐Soluble Phenylphosphane to Avoid Interaction with Cyclodextrin

The ability of cyclodextrin to interact with meta‐trisulfonated triphenylphosphane derivatives bearing one or two methyl (or methoxy) groups on the aromatic ring has been investigated by NMR and UV‐vis spectroscopy. In the case of native β‐cyclodextrin (β‐CD), the presence of one methyl or methoxy group in the ortho‐position on each aromatic ring is necessary to hamper the formation of an inclusion complex between the β‐CD and meta‐trisulfonated triphenylphosphane derivatives. In the case of methylated β‐CD, the formation of an inclusion complex is only observed when the meta‐trisulfonated triphenylphosphane contains a methyl group in the para‐position. The poor affinity of methylated β‐CD towards modified trisulfonated triphenylphosphanes was attributed to the steric hindrance generated by the methyl groups on the CD secondary face. The absence or presence of an interaction between phosphanes and methylated β‐CD was also confirmed by catalytic experiments. Thus, the phosphanes that do not interact with the methylated CD were the most efficient mass‐transfer promoters in an aqueous biphasic palladium‐catalyzed Tsuji–Trost reaction.     

Methyl 9(10)-formylstearate by selective hydroformylation of oleic oils

A highly selective catalyst system has been discovered for the hydroformylation of methyl oleate into methyl 9(10)-formylstearate in high yields. A rhodium catalyst in the presence of triphenylphosphine is used with oleic esters, acids or triglycerides. Hydroformylation proceeds smoothly at 95-110C with a 1:1 mixture of H₂ and CO at 500 to 2000 psi with or without a solvent, such as toluene. The formylstearate obtained in 90% to 99% conversion from oleate can be either hydrogenated (Raney Ni) or reduced (NaBH₄) to hydroxymethylstearate or oxidized (KMnO₄) to carboxystearate. According to TLC and mass spectrometry, the methylated carboxystearate consists of about equal proportions of the 9 and 10 isomers. Addition of triphenylphosphine inhibits isomerization of the double bond and leads to the formation of a rhodium carbonyl triphenylphosphine complex, which is apparently the active catalyst. Other known methods for hydroformylation (cobalt carbonyl) and carboxylation (Koch’s method) of oleate give a wide distribution of isomers. Presented at the ISF-AOCS Meeting, Chicago, September 1970.     

The stability of a polymer-supported rhodium complex in the batch hydroformylation of 1-hexene. II. Effect of reaction conditions

The stability of a polymer-supported rhodium complex has been studied in a batch process for hydroformylation of 1-hexene, using [Rh(CO)₂Cl]₂ as the catalytic precursor and poly(vinylbenzyl diethylenetriamine) as the polymeric ligand. It has been found that the reaction conditions, temperature, pressure, solvent and reaction time etc., have considerable influence on the degree of rhodium elution. Elution of rhodium is serious under normal conditions but low in certain blank experiments. These results indicate that rhodium elution is probably related to the substitution of a low molecular ligand for the polymeric ligand in the catalytic cycle. Several possible mechanisms of rhodium elution based on these results are proposed.     

A water‐soluble supramolecular‐structured photoinitiator between methylated β‐cyclodextrin and 2,2‐dimethoxy‐2‐phenylacetophenone

A water‐soluble supramolecular‐structured photoinitiator (SSPI) was synthesized by supramolecular self‐assembling between methylated β‐cyclodextrin (MβCD) and hydrophobic 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA). The structure of SSPI was characterized by X‐ray diffraction, FTIR, ¹H NMR, UV–vis, and fluorescence spectra. The results indicated that MβCD and DMPA had formed 1 : 1 inclusion complex in methanol solution. The binding constant (K) for the complex was 7.51 × 10²M^?1. SSPI could be dissolved in water easily and its water‐solubility was 15.3 g/100 mL. SSPI was the more efficient photoinitiator than DMPA for the photopolymerization of acrylamide (AM) in homogeneous aqueous system. The conversion for photopolymerization of trimethylolpropane triacrylate system initiated by SSPI was similar to that initiated by DMPA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007