Hydroformylation Of 1-hexene Research Articles

Recycle and recovery of rhodium complexes with water-soluble and amphiphilic phosphines in ionic liquids for hydroformylation of 1-hexene

A biphasic catalysis system composed of ionic liquid and rhodium complexes with water-soluble or amphiphilic phosphine ligands bearing water-soluble groups of sodium sulfonate have been employed for hydroformylation of 1-hexene. The experimental results show that the activity is almost independent of the hydrotropicity of the phosphine ligands in BMI·BF4. In this system, the extraction of phosphine species by the organics from the IL phase was quite low but larger than that of rhodium species and showed rather good stability of catalytic activity. A slight decrease in the aldehyde n/i ratio during the catalyst reuse could be recovered, in part, by replenishing certain amount of ligand into the used catalyst system.

Hydroformylation of 1-hexene using polymer-supported rhodium catalysts in supercritical carbon dioxide

Hydroformylation of 1-hexene was carried out in supercritical CO 2 (scCO 2) and in organic solvents (toluene and ethyl acetate) using polymer-supported rhodium catalysts, which were prepared from polystyrene bound triphenylphosphine (TPP) and dicarbonylacetylecetonato rhodium. Preparation variables such as TPP/Rh ratio, time of rhodium precursor fixation on the support and time of syngas pretreatment do not produce significant effects on the reaction. The product distribution slightly changes with CO 2 pressure. The conversion increases appreciably as H 2 pressure is raised in scCO 2 but CO retards the reaction. The influence of H 2 pressure in scCO 2 is slightly different from that in toluene. Changes of the structure of rhodium complexes on the polymer during the catalyst preparation and the reaction were investigated by diffuse reflectance FT-IR. It should be noted that the catalyst is recyclable for the reaction in scCO 2 and that the reaction rate and selectivity of the hydroformylation are much higher than those in the organic solvents.

A Model Iridium Hydroformylation System with the Large Bite Angle Ligand Xantphos: Reactivity with Parahydrogen and Implications for Hydroformylation Catalysis

Iridium complexes containing the large bite angle bisphosphine ligand xantphos have been synthesized and their reactivity studied. Several of these complexes are the first reported Ir(xantphos) systems to be characterized by X-ray diffraction. Variable-temperature NMR spectroscopic studies of IrI(CO)2(xantphos) (1-I) and Ir(COEt)(CO)2(xantphos) (8) show two separate dynamic processes in which the phosphorus donors and the backbone methyl groups of the xantphos ligand are exchanged. The addition of parahydrogen (p-H2) to 1-I leads to the formation of two dihydride isomers including one in which both hydride ligands are trans to the phosphorus donors, suggestive of an Ir(I) xantphos intermediate with the ligand chelated in a trans-spanning fashion (2b). The bromide and chloride Ir(I) analogues (1-Br and 1-Cl) also form this isomer upon reaction with parahydrogen, with 1-Cl yielding only this dihydride species. The trihydride complex IrH3(CO)(xantphos) (7) has been prepared, and its exchange with free hydrogen at elevated temperature is confirmed by reaction with p-H2. The hydride complexes IrH(CO)2(xantphos) (6) and IrH3(CO)(xantphos) (7), as well as the propionyl complex 8, are modest catalysts for the hydroformylation of 1-hexene and styrene under mild conditions. The addition of p-H2 to 8 permits direct observation of the propionyl dihydride species IrH2(COEt)(CO)(xantphos) (9) under both thermal and photolytic conditions, as well as unusual but weak polarization of the aldehydic proton of the propanal product that forms upon reductive elimination from 9.

An environmentally friendly hydroformylation using carbon dioxide as a reactant catalyzed by immobilized Ru-complex in ionic liquids

A mixed ionic liquid [bmim][Cl + NTf 2] system was successfully used as a reaction medium for Ru-catalyzed hydroformylation of 1-hexene with carbon dioxide in the absence of toxic CO and any volatile organic solvents. The yields and TONs are higher than those reported previously using conventional organic solvents. The product can be readily separated by distillation, and the reaction medium containing the Ru-catalyst was successfully recycled.

Synthesis and characterization of [HRu(CO)(CH3CN)(TPPTS)3]BF4: Catalytic properties in the aqueous-biphasic hydroformylation of olefins

The new water soluble complex [HRu(CO)(CH3CN)(TPPTS)3]BF4 (TPPTS=tris[(m-sulfonated)phenyl]phosphine P(m-C6H4SO3Na)3) has been synthesized by ligand exchange techniques from the corresponding PPh3 derivative in a methoxyethanol–water mixture. The new complex was characterized by FTIR, UV–vis, and 1H NMR and 31P {1H} NMR spectroscopy and used as catalyst precursor for the aqueous biphasic hydroformylation of several olefins and their mixtures under moderate reaction conditions. The catalytic activity order found was: 1-hexene>allylbenzene>2,3-dimethyl-1-butene>styrene>cyclohexene. The sulphur tolerance of this complex was also investigated using thiophene as a model molecule; it was found that the new complex maintains its activity when the thiophene concentration is below 500ppm. The mercury test in independent experiments showed no interference of the Hg at all with the evolution of the reaction, demonstrating that the catalysis is performed by molecular species. The recyclable nature of the complex was demonstrated during 1-hexene hydroformylation where at the end of each catalytic reaction all the metal remains in the aqueous phase.

Hydroformylation of 1-hexene for oxygenate fuels via promoted cobalt/active carbon catalysts at low-pressure

The hydroformylation of 1-hexene was catalyzed with active carbon-supported cobalt catalysts under the low syngas pressure. Small amount of Pt, Pd and Ru, added as promoters in Co/AC, led to a great improvement of catalytic activity for hydroformylation of 1-hexene. The promotional effect of Ru for Co/AC catalyst was the best in this study as the highest activity and selectivity for oxygenate formation. Meanwhile, the activity of 1-hexene hydroformylation increased with increasing Ru loading. Ru added was bulk-rich in the active carbon supported cobalt particles, showing very low surface Ru density. This kind of unbalanced alloy formation determined the highest performance of Ru added Co/AC catalyst, via small particles but high reduction degree, keeping more CO in non-dissociative state and lowering surface hydrogen pressure.

Preparation and performance of anchored heterogenized rhodium complex catalyst for hydroformylation

In order to solve the difficult problem in separation of homogeneous catalyst from the reaction mixture, heterogenized rhodium carbonyl complex catalyst for hydroformylation of olefins was prepared by copolymerization of functionalized 3-aminopropyltriethoxysalane with tetraethoxysalane (TEOS) via the sol–gel method. The catalyst was characterized by FT-IR, X-ray photoelectron spectroscopy (XPS), ICP and N 2 absorption. The activity, selectivity and stability of this catalyst for 1-hexene hydroformylation have been examined. It was concluded the activity depended on the surface area of the catalyst matrix, which varied according to the pH in the sol–gel process. The conversion of 1-hexene reached 98.8%, with a selectivity of 99.6% of aldehydes and the n/ i ratio of 0.86 under optimized conditions. Furthermore, it showed excellent stability and reusability, the catalyst was used for six times without obvious loss of activity.

Hydroesterification and hydroformylation of 1-hexene catalyzed by rhodium complexes immobilized on poly(4-vinylpyridine)

This work describes the catalytic hydroesterification and hydroformylation of 1-hexene by [Rh(cod)(amine) 2](PF 6) complexes (cod = 1,5-cyclooctadiene; amine = pyridine, 2-picoline, 3-picoline, 4-picoline, 3,5-lutidine or 2,6-lutidine) immobilized on poly(4-vinylpyridine) in contact with methanol under carbon monoxide atmosphere. In the presence of these immobilized complexes, 1-hexene, CO and methanol give methyl-heptanoate and 1,1-dimethoxy-heptane as the main reaction products and minor amounts of heptanal. The acetal by-product comes from the nucleophilic addition reaction of the methanol with the formed heptanal. Other products, such as H 2 and CO 2 coming from the catalysis of the water–gas shift reaction are observed. The reaction products distribution depends on the nature of the coordinated amine to the rhodium center and the reaction parameters.

Monomeric ruthenium carbonyls containing 2-substituted pyrazines: From synthesis to catalytic activity in 1-hexene hydroformylation

Synthesis and catalytic properties of a series of ruthenium carbonyl complexes with 2-substituted pyrazine ligands (pz–R; R = Cl, OMe, SMe, CN, NH 2) have been studied. Reactions between the [Ru(CO) 3Cl 2] 2 and the pyrazines led mainly to mononuclear compounds of the type [Ru(CO) 3Cl 2(R–pz)]. All of these ruthenium pyrazine compounds showed activity in 1-hexene hydroformylation. With an exception of NH 2, addition of the substituent to the pyrazine ring was found to improve the catalytic activity compared to the unsubstituted pyrazine. The catalytic cycle was studied by computational DFT methods. The results suggest that the key step in the formation of the active species involves release of one of the carbonyl in the cis position with respect to the pyrazine ring.

Recoverable Catalysts Noncovalently Bound to a Hyperbranched Polyelectrolyte

Polyelectrolytes with Ph2P(C6H4-p-SO3-) counterions were prepared by ion exchange from hyperbranched polycations with a polyglycerol-based polyether scaffold and 1,2-dimethylimidazolium end groups. Upon exposing a mixture of the polyelectrolyte with [Rh(acac)(CO)2] in DMSO-d6 to 1 atm CO/H2, a large portion of the rhodium precursor is converted to [(phosphine)3Rh(H)(CO)]. Hydroformylation of 1-hexene in methanol as a model reaction proceeds with moderate activities at 80 °C, 30 bar CO/H2. The polyelectrolyte-bound catalyst was recovered by ultrafiltration and reused up to three times.

Synthesis, characterization, reactivity and theoretical studies of ruthenium carbonyl complexes containing ortho-substituted triphenyl phosphanes

A series of ruthenium o-phosphane complexes was synthesized and characterized. The reactivity of the prepared complexes was studied by using them as catalysts for the hydroformylation of 1-hexene. The activities depended on the binding mode of the phosphane and on the strength of the ruthenium–phosphane interaction. Strongly coordinated chelating [2-(dimethylamino)phenyl]-(diphenyl) phosphane and [2-(methylthio)phenyl]-(diphenyl) phosphane showed poor activity, while weakly chelated [2-(methoxy)phenyl]-(diphenyl) phosphane and non-chelating phosphanes such as [2-(methyl)phenyl]-(diphenyl) phosphane or [2-(ethyl)phenyl]-(diphenyl) phosphane led to higher activities.

OperandoHigh-Pressure NMR and IR Study of the Hydroformylation of 1-Hexene by 1,1‘-Bis(Diarylphosphino)metallocene-Modified Rhodium(I) Catalysts

Some rhodium(I) complexes of the general formula [Rh(P−P)(COD)]X were synthesized and characterized by multinuclear NMR spectroscopy (COD = cyclocta-1,5-diene; P−P = 1,1‘-bis(diphenylphosphino)ferrocene, dppf, X = BPh4, PF6; P−P = 1,1‘-bis(diphenylphosphino)ruthenocene, dppr, X = BPh4; P−P = 1,1‘-bis(diphenylphosphino)osmocene, dppo, X = BPh4, PF6; P−P = 1,1‘-bis(diphenylphosphino)octamethylferrocene, dppomf, X = BAr‘4; P−P = (1,1‘-bis(di(o-isopropylphenyl)phosphino)ferrocene, o-iPr-dppf, X = BAr‘4). These complexes were employed as catalyst precursors for the hydroformylation of 1-hexene in THF either in standard autoclaves or in high-pressure (HP) NMR tubes and IR cells. All catalysts exhibited good activity (TOFs ranging from 700 to 1000 mol aldehyde (mol cat)-1 h-1) and moderate regioselectivity in n-heptanal (67−74%). Irrespective of the rhodium precursor, the HP-NMR experiments under catalytic conditions showed the formation of kinetic dicarbonyl products at room temperature, which were independentl...

Rhodium(I) complexes with 1′-(diphenylphosphino)ferrocenecarboxylic acid as active and recyclable catalysts for 1-hexene hydroformylation

The rhodium complex trans-[Rh(CO)(Hdpf-κ P)(dpf-κ 2 O, P)] ( 1), (Hdpf = 1′-(diphenylphosphino)ferrocenecarboxylic acid) was used as an efficient and recyclable catalyst for 1-hexene hydroformylation producing ca. 80% of aldehydes at 10 atm CO/H 2 and 80 °C. After the reaction, unchanged complex 1 was separated from the reaction mixture and used again three times with the same catalytic activity. The effect of modifying ligands, phosphines and phosphites, on the reactivity of 1 was investigated. The active catalytic systems containing 1 or trans-[Rh(CO)(L)(dpf-κ 2 O, P)] ( 2) were formed in situ from acetylacetonato rhodium(I) precursors [Rh(CO) 2(acac)] ( 3) or [RhL(CO)(acac)] ( 4) and Hdpf or Medpf (L = phosphine, Medpf = methyl ester of Hdpf).

Hydroformylation of 1-hexene for oxygenate fuels on supported cobalt catalysts

The supported Co/SiO 2 and Co/active carbon (A.C.) catalysts were studied as heterogeneous catalysts in the liquid-phase hydroformylation of 1-hexene. The pore size of silica support significantly influenced the activity and selectivity of Co/SiO 2 catalysts in hydroformylation of 1-hexene. The silica supported cobalt catalyst exhibited the best hydroformylation reaction performance at 403 K, and catalytic activity for this kind of catalyst increased with the increasing initial reaction pressure. The addition of small amount of noble metal significantly improved the activity and selectivity for Co/SiO 2. The solvent effects for Co/SiO 2 and Co/A.C. catalysts in the hydroformylation reaction of 1-hexene were investigated and alcoholic solvents promoted the oxygenate formation significantly.

Hydroformylation of 1-hexene using Rh/TPPTS complex exchanged on anion exchange resin: kinetic studies

The exchange of the Rh/Triphenylphosphine trisulfonate sodium [TPPTS] complex on to an anion exchange resin results in a stable heterogenized catalyst for the hydroformylation of alkenes. The kinetics of hydroformylation of 1-hexene using Rh/TPPTS complex exchanged on anion exchange resin to Amberlite IRA-93 has been investigated for the first time. The rate of the reaction was found to be dependent on the partial pressure of hydrogen and 1-hexene concentrations with a first order. A maximum in the rate with increasing partial pressure of carbon monoxide was observed. A rate model has been proposed which predicts the observed rate data within reasonable error. The activation energy was found to be 84.37 kJ/mol.

Kinetic Studies on the Hydroformylation of 1-Hexene Using RhCl(AsPh3)3 as a Catalyst

The detail kinetic study of 1-hexene hydroformylation using RhCl(AsPh3)3 as a homogeneous catalyst has been investigated. The present kinetic study involves the effect of concentrations of 1-hexene and catalyst, partial pressures of CO and H2, agitation speed, and temperature on the rate of hydroformylation. Additionally, the studies of deactivation of the catalyst RhCl(AsPh3)3 with temperature have also been done. It was observed that the rates of hydroformylation reaction were increased on increasing the initial concentrations of 1-hexene, catalyst, and partial pressures of CO and H2 at lower ranges. The activation energy was found to be 42.74 kJ/mol. A nonlinear semiempirical kinetic model was also developed to be the best fit with 11.6% error.

Olefin hydroformylation by sol-gel entrapped rhodium catalysts bearing hydrolysable ligands

Rhodium complexes prepared in situ from [Rh(OMe)(COD)]2, [Rh(CO)2(acac)], [Rh(cod)(acac)] or [Rh(cod)(PPh3)2]+BPh 4- with ligands as HS(CH2)3Si(OMe)3, Ph2P(CH2)2S(CH 2)3Si(OMe)3 or Ph2P(CH2)2Si(OMe) 3 were immobilized in inorganic and hybrid silica matrices via the sol-gel process. The inorganic matrices were prepared with tetramethylorthosilicate while for the hybrid ones 1,4-bis(triethoxysilyl)benzene or 1,2-bis(triethoxysilyl)ethane were used as co-condensation agents. The system based on [Rh(CO)2(acac)]/ Ph2P(CH2)2S(CH 2)3Si(OMe)3 was active in the hydroformylation of 1-hexene and 1-octadecene without any rhodium leaching. It could also be used in the absence of a solvent, as observed in the hydroformylation of 1-decene. Although the best system was based on a hybrid microporous matrix, no straightforward correlation between matrix composition, condensation degree and surface properties could be found.

MCM-41 Supported Water-soluble TPPTS–Rh Complex in Ionic Liquids: A New Robust Catalyst for Olefin Hydroformylation

Abstract MCM-41 mesoporous silicas-supported water-soluble TPPTS–Rh complex in the ionic liquid TMGL exhibited high performance and stability for the hydroformylation of 1-hexene, and the catalyst system could be reused many times without reducing the activity and selectivity.

Thione complexes of Rh(i): a first comparison with the bonding and catalytic activity of related carbene and imine compounds

Heterocyclic mono(thione), trans-bis(thione), cis-bis(thione), trans-(carbene-thione), cis-(carbene-thione), trans-(phosphine-thione) and mono(imine) complexes of rhodium(I) have been prepared and fully characterised. Chloro(eta(4)-1,5-cyclooctadiene)(L)rhodium(I)(1a, L = 1,3-diisopropyl-4,5-dimethyl-2,3-dihydro-1H-imidazol-2-thione; 1b L = 1,3,4,5-tetramethyl-2,3-dihydro-1H-imidazol-2-thione) appear as isomers at room temperature due to slow coordination exchange on the S-donor atom. In the three structures determined, the substituent on the sulfur appears syn to Cl. Hindered rotation about the Rh-carbene bond is revealed in the NMR spectra of seven new complexes with isopropyl substituents on the heterocyclic carbene ligands. The trans influence of the thione ligands is smaller than that of carbenes but larger than that shown by imines and chloride. Thione complexes are better catalyst precursors than the carbene complexes for the hydroformylation of 1-hexene under the chosen reaction conditions: 80 degrees C, 8 MPa CO-H2(1:1), 16 h, 1:1000 catalyst to 1-hexene ratio.

Low-pressure hydroformylation of 1-hexene over active carbon-supported noble metal catalysts

The low-pressure hydroformylation of 1-hexene was catalyzed with active carbon-supported noble metal catalysts, such as Rh/AC, Pd/AC, Ru/AC and Pt/AC. In this study, the Rh/AC catalyst exhibited the best property for hydroformylation of 1-hexene with high 1-hexene conversion and high oxygenates’ yield, and Rh loading significantly influenced the catalytic activity of hydroformylation of 1-hexene. The active carbon-supported cobalt catalyst was studied for comparison. Acting as support for noble metals, the active carbon was more advantageous to hydroformylation of 1-hexene than silica, due to the high BET surface area, contributing to high dispersion of the supported metal, and to the beneficial characteristics in carbonylation, contributing to CO insertion. The hydroformylation reaction on supported Rh catalysts was carried out at different reaction conditions, such as in different temperature from 353 to 433 K and in different initial pressure from 1.0 to 5.0 MPa, to find the most favorable reaction conditions. Solvent effects for hydroformylation of 1-hexene, as well as reaction mechanism on active carbon-supported noble metal catalysts were also studied. Nonpolar and non-protonic solvents showed promotional effects.